,,familiar ,,letters ,,on ,,chemistry1  
,,and ,,its ,,relation ,,to ,,commerce1 
,,physiology1 ,,and ,,agriculture1  ,,by
 ,,justus ,,liebig1 ,m4,d41 ,,ph4 ,d41  
,f4,r4,s41  ,,professor ,,of ,,chemistry
 ,,in ,,the ,,university ,,of ,,giessen4
   ,,edited ,,by  ,,john ,,gardner1     
,m4,d41   ,,member ,,of ,,the ,,chemical
 ,,society4    ,second ,edition1        
,corrected4  ,,london3  ,,mdcccxliv4    
,,preface   ,the ,letters contained in  
this little ,volume embrace some of the 
most important points of the science of 
,chemistry1 in their application to     
,natural ,philosophy1 ,physiology1      
,agriculture1 and ,commerce4 ,some of   
them treat of subjects which have       
already been1 or will hereafter be1 more
 fully discussed in my larger works4    
,they were intended to be mere sketches1
 and were written for the especial      
purpose of exciting the attention of    
governments1 and an enlightened public1 
to the necessity of establishing        
,schools of ,chemistry1 and of          

promoting1 by every means1 the study of 
a science so intimately connected with  
the arts1 pursuits1 and social          
well-being of modern civilised nations4 
,for my own part ,i do not scruple to   
avow the conviction1 that ere long1 a   
knowledge of the principal truths of    
,chemistry will be expected in every    
educated man1 and that it will be as    
necessary to the ,statesman1 the        
,political ,economist1 and the          
,practical ,agriculturist1 as it is     
already indispensable to the ,physician1
 and the ,manufacturer4  ,in ,germany1  
such of these ,letters as have been     
already published1 have not failed to   
produce some of the results anticipated4
 ,new professorships have been          
established in the ,universities of     
,goettingen and ,wuertzburg1 for the    
express purpose of facilitating the     
application of chemical truths to the   
practical arts of life1 and of following
 up the new line of investigation and   
research--the bearing of ,chemistry upon

 ,physiology1 ,medicine1 and            
,agriculture1--which may be said to be  
only just begun4  ,my friend1 ,dr4      
,ernest ,dieffenbach1 one of my first   
pupils1 who is well acquainted with all 
the branches of ,chemistry1 ,physics1   
,natural ,history1 and ,medicine1       
suggested to me that a collection of    
these ,letters would be acceptable to   
the ,english public1 which has so       
favourably received my former works4  ,i
 readily acquiesced in the publication  
of an ,english edition1 and undertook to
 write a few additional ,letters1 which 
should embrace some conclusions ,i have 
arrived at1 in my recent investigations1
 in connection with the application of  
chemical science to the physiology of   
plants and agriculture4  ,my esteemed   
friend1 ,dr4 ,gardner1 has had the      
kindness to revise the manuscript and   
the proof sheets for publication1 for   
which ,i cannot refrain expressing my   
best thanks4  ,it only remains for me to
 add a hope1 that this little offering  

may serve to make new friends to our    
beautiful and useful science1 and be a  
remembrancer to those old friends who   
have1 for many years past1 taken a      
lively interest in all my labours4      
,,justus ,,liebig  ,giessen1 ,aug4      
#ahdc4       ,,contents      ,,letter ,i
  ,the ,subject proposed4 ,materials    
employed for ,chemical ,apparatus3--    
,,glass--,,caoutchouc--,,cork--,,platinu
m4 ,,the ,,balance4 ,the ,elements of   
the ,ancients1 represent the forms of   
matter4 ,lavoisier and his successors4  
,study of the materials composing the   
,earth4 ,synthetic production of        
,minerals--,,lapis ,,lazuli4 ,organic   
,chemistry4   ,,letter ,,ii  ,changes of
 ,form which every kind of ,matter      
undergoes4 ,conversion of ,gases into   
,liquids and ,solids4 ,carbonic         
,acid--its curious properties in a solid
 state4 ,condensation of ,gases by      
porous bodies4 ,by ,spongy ,platinum4   
,importance of this property in ,nature4
   ,,letter ,,iii  ,the ,manufacture of 

,soda from ,culinary ,salt2 its         
importance in the ,arts and in          
,commerce4 ,glass--,soap--,sulphuric    
,acid4 ,silver ,refining4 ,bleaching4   
,,trade ,,in ,,sulphur4   ,,letter ,,iv 
,connection of ,theory with ,practice4  
,employment of ,,magnetism as a moving  
power--its impracticability4 ,relation  
of ,coals and ,zinc as economic sources 
of ,force4 ,manufacture of ,beet-root   
,sugar--its impolicy4 ,gas for          
illumination4   ,,letter ,v             
,,isomerism1 or identity of composition 
in bodies with different chemical and   
physical properties4 ,,crystallisation4 
,,amorphism4 ,,isomorphism1 or          
similarity of properties in bodies      
totally different in composition4       
,,letter ,,vi  ,,alliance ,,of          
,,chemistry ,,with ,,physiology4        
,division of ,food into nourishment1 and
 materials for combustion4 ,effects of  
,atmospheric ,oxygen4 ,balance of       
,,carbon and ,,oxygen4   ,,letter ,,vii 
,,animal ,,heat1 its laws and influence 

on the ,animal ,functions4 ,loss and    
,,supply4 ,influence of ,climate4 ,fuel 
of ,animal ,heat4 ,agency of ,oxygen in 
,disease4 ,respiration4   ,,letter      
,,viii  ,,aliments4 ,constituents of the
 ,blood4 ,fibrine1 ,albumen4 ,inorganic 
,substances4 ,isomerism of ,fibrine1    
,albumen1 and elements of nutrition4    
,relation of animal and vegetable       
organisms4   ,,letter ,,ix  ,growth of  
,animals4 ,uses of ,butter and ,milk4   
,metamorphoses of ,tissues4 ,food of    
,carnivora1 and of the ,horse4          
,,letter ,x  ,application of the        
preceding facts to ,man4 ,division of   
human ,food4 ,uses of ,gelatine4        
,,letter ,,xi  ,,circulation ,,of       
,,matter ,,in ,,the ,,animal ,,and      
,,vegetable ,,kingdoms4 ,the ,ocean4    
,,agriculture4 ,,restitution ,,of ,,an  
,,equilibrium ,,in ,,the ,,soil4 ,causes
 of the exhaustion of ,land4 ,virginia4 
,england4 ,relief gained by importation 
of bones4 ,empirical farming            
unsatisfactory4 ,necessity for          

scientific principles4 ,influence of the
 atmosphere4 ,of ,saline and ,earthy    
matters of the soil4   ,,letter ,,xii   
,,science ,,and ,,art ,,of              
,,agriculture4 ,,necessity ,,of         
,,chemistry4 ,rationale of agricultural 
processes4 ,washing for gold4   ,,letter
 ,,xiii  ,,illustration ,,of ,,the      
,,necessity ,,of ,,chemistry ,,to       
,,advance ,,and ,,perfect ,,agriculture4
 ,manner in which ,,fallow ameliorates  
the soil4 ,uses of ,lime4 ,effects of   
,burning4 ,of ,marl4   ,,letter ,,xiv   
,,nature ,,and ,,effects ,,of ,,manures4
 ,animal bodies subject to constant     
waste4 ,parts separating--exuviae--waste
 vegetable matters--together contain all
 the elements of the soil and of food4  
,various value of excrements of         
different animals as manure4   ,,letter 
,,xv  ,,source ,,of ,,the ,,carbon ,,and
 ,,nitrogen ,,of ,,plants4 ,produce of  
,carbon in ,forests and ,meadows        
supplied only with mineral aliments     
prove it to be from the atmosphere4     

,relations between ,mineral             
constituents1 and ,carbon and ,nitrogen4
 ,effects of the ,carbonic ,acid and    
,ammonia of ,manures4 ,necessity of     
inorganic constituents to the formation 
of aliments1 of blood1 and therefore of 
nutrition4 ,,necessity ,,of ,,inquiries 
by ,,analysis to advance ,,agriculture4 
,,letter ,,xvi  ,,results ,,of ,,the    
,,author',s ,,latest ,,inquiries4       
,superlative importance of the          
,,phosphates ,,of ,,lime and ,,alkalies 
to the cultivation of the ,,cerealia4   
,sources of a ,,supply of these         
,,materials4      ,,letters ,,on        
,,chemistry     ,,letter ,i   ,my dear  
,sir1  ,the influence which the science 
of chemistry exercises upon human       
industry1 agriculture1 and commerce2    
upon physiology1 medicine1 and other    
sciences1 is now so interesting a topic 
of conversation everywhere1 that it may 
be no unacceptable present to you if ,i 
trace in a few familiar letters some of 
the relations it bears to these various 

sciences1 and exhibit for you its actual
 effect upon the present social         
condition of mankind4  ,in speaking of  
the present state of chemistry1 its rise
 and progress1 ,i shall need no apology 
if1 as a preliminary step1 ,i call your 
attention to the implements which the   
chemist employs--the means which are    
indispensable to his labours and to his 
success4  ,these consist1 generally1 of 
materials furnished to us by nature1    
endowed with many most remarkable       
properties fitting them for our         
purposes2 if one of them is a production
 of art1 yet its adaptation to the use  
of mankind1--the qualities which render 
it available to us1--must be referred to
 the same source as those derived       
immediately from nature4  ,cork1        
,platinum1 ,glass1 and ,caoutchouc1 are 
the substances to which ,i allude1 and  
which minister so essentially to modern 
chemical investigations4 ,without them1 
indeed1 we might have made some         
progress1 but it would have been slow2  

we might have accomplished much1 but it 
would have been far less than has been  
done with their aid4 ,some persons1 by  
the employment of expensive substances1 
might have successfully pursued the     
science2 but incalculably fewer minds   
would have been engaged in its          
advancement4 ,these materials have only 
been duly appreciated and fully adopted 
within a very recent period4 ,in the    
time of ,lavoisier1 the rich alone could
 make chemical researches2 the necessary
 apparatus could only be procured at a  
very great expense4  ,and first1 of     
,glass3 every one is familiar with most 
of the properties of this curious       
substance2 its transparency1 hardness1  
destitution of colour1 and stability    
under ordinary circumstances3 to these  
obvious qualities we may add those which
 especially adapt it to the use of the  
chemist1 namely1 that it is unaffected  
by most acids or other fluids contained 
within it4 ,at certain temperatures it  
becomes more ductile and plastic than   

wax1 and may be made to assume in our   
hands1 before the flame of a common     
lamp1 the form of every vessel we need  
to contain our materials1 and of every  
apparatus required to pursue our        
experiments4  ,then1 how admirable and  
valuable are the properties of ,cork6   
,how little do men reflect upon the     
inestimable worth of so common a        
substance6 ,how few rightly esteem the  
importance of it to the progress of     
science1 and the moral advancement of   
mankind6--,there is no production of    
nature or art equally adapted to the    
purposes to which the chemist applies   
it4 ,cork consists of a soft1 highly    
elastic substance1 as a basis1 having   
diffused throughout a matter with       
properties resembling wax1 tallow1 and  
resin1 yet dissimilar to all of these1  
and termed suberin4 ,this renders it    
perfectly impermeable to fluids1 and1 in
 a great measure1 even to gases4 ,it is 
thus the fittest material we possess for
 closing our bottles1 and retaining     

their contents4 ,by its means1 and with 
the aid of ,caoutchouc1 we connect our  
vessels and tubes of glass1 and         
construct the most complicated          
apparatus4 ,we form joints and links of 
connexion1 adapt large apertures to     
small1 and thus dispense altogether with
 the aid of the brassfounder and the    
mechanist4 ,thus the implements of the  
chemist are cheaply and easily procured1
 immediately adapted to any purpose1 and
 readily repaired or altered4  ,again1  
in investigating the composition of     
solid bodies1--of minerals1--we are     
under the necessity of bringing them    
into a liquid state1 either by solution 
or fusion4 ,now vessels of glass1 of    
porcelain1 and of all non-metallic      
substances1 are destroyed by the means  
we employ for that purpose1--are acted  
upon by many acids1 by alkalies and the 
alkaline carbonates4 ,crucibles of gold 
and silver would melt at high           
temperatures4 ,but we have a combination
 of all the qualities we can desire in  

,platinum4 ,this metal was only first   
adapted to these uses about fifty years 
since4 ,it is cheaper than gold1 harder 
and more durable than silver1 infusible 
at all temperatures of our furnaces1 and
 is left intact by acids and alkaline   
carbonates4 ,platinum unites all the    
valuable properties of gold and of      
porcelain1 resisting the action of heat1
 and of almost all chemical agents4  ,as
 no mineral analysis could be made      
perfectly without platinum vessels1 had 
we not possessed this metal1 the        
composition of minerals would have yet  
remained unknown2 without cork and      
caoutchouc we should have required the  
costly aid of the mechanician at every  
step4 ,even without the latter of these 
adjuncts our instruments would have been
 far more costly and fragile4           
,possessing all these gifts of nature1  
we economise incalculably our time--to  
us more precious than money6  ,such are 
our instruments4 ,an equal improvement  
has been accomplished in our laboratory4

 ,this is no longer the damp1 cold1     
fireproof vault of the metallurgist1 nor
 the manufactory of the druggist1 fitted
 up with stills and retorts4 ,on the    
contrary1 a light1 warm1 comfortable    
room1 where beautifully constructed     
lamps supply the place of furnaces1 and 
the pure and odourless flame of gas1 or 
of spirits of wine1 supersedes coal and 
other fuel1 and gives us all the fire we
 need2 where health is not invaded1 nor 
the free exercise of thought impeded3   
there we pursue our inquiries1 and      
interrogate ,nature to reveal her       
secrets4  ,to these simple means must be
 added ,the ,balance1 and then we       
possess everything which is required for
 the most extensive researches4  ,the   
great distinction between the manner of 
proceeding in chemistry and natural     
philosophy is1 that one weighs1 the     
other measures4 ,the natural philosopher
 has applied his measures to nature for 
many centuries1 but only for fifty years
 have we attempted to advance our       

philosophy by weighing4  ,for all great 
discoveries chemists are indebted to the
 balance--that incomparable instrument  
which gives permanence to every         
observation1 dispels all ambiguity1     
establishes truth1 detects error1 and   
guides us in the true path of inductive 
science4  ,the balance1 once adopted as 
a means of investigating nature1 put an 
end to the school of ,aristotle in      
physics4 ,the explanation of natural    
phenomena by mere fanciful speculations1
 gave place to a true natural           
philosophy4 ,fire1 air1 earth1 and      
water1 could no longer be regarded as   
elements4 ,three of them could          
henceforth be considered only as        
significative of the forms in which all 
matter exists4 ,everything with which we
 are conversant upon the surface of the 
earth is solid1 liquid1 or aeriform2 but
 the notion of the elementary nature of 
air1 earth1 and water1 so universally   
held1 was now discovered to belong to   
the errors of the past4  ,fire was found

 to be but the visible and otherwise    
perceptible indication of changes       
proceeding within the1 so called1       
elements4  ,lavoisier investigated the  
composition of the atmosphere and of    
water1 and studied the many wonderful   
offices performed by an element common  
to both in the scheme of nature1 namely1
 oxygen3 and he discovered many of the  
properties of this elementary gas4      
,after his time1 the principal problem  
of chemical philosophers was to         
determine the composition of the solid  
matters composing the earth4 ,to the    
eighteen metals previously known were   
soon added twenty-four discovered to be 
constituents of minerals4 ,the great    
mass of the earth was shown to be       
composed of metals in combination with  
oxygen1 to which they are united in one1
 two1 or more definite and unalterable  
proportions1 forming compounds which are
 termed metallic oxides1 and these1     
again1 combined with oxides of other    
bodies1 essentially different to metals1

 namely1 carbon and silicium4 ,if to    
these we add certain compounds of       
sulphur with metals1 in which the       
sulphur takes the place of oxygen1 and  
forms sulphurets1 and one other         
body1--common salt1--7which is a        
compound of sodium and chlorine71 we    
have every substance which exists in a  
solid form upon our globe in any very   
considerable mass4 ,other compounds1    
innumerably various1 are found only in  
small scattered quantities4  ,the       
chemist1 however1 did not remain        
satisfied with the separation of        
minerals into their component elements1 
i4e4 their analysis2 but he sought by   
synthesis1 i4e4 by combining the        
separate elements and forming substances
 similar to those constructed by nature1
 to prove the accuracy of his processes 
and the correctness of his conclusions4 
,thus he formed1 for instance1          
pumice-stone1 feldspar1 mica1 iron      
pyrites1 c4 artificially4  ,but of all  
the achievements of inorganic chemistry1

 the artificial formation of lapis      
lazuli was the most brilliant and the   
most conclusive4 ,this mineral1 as      
presented to us by nature1 is calculated
 powerfully to arrest our attention by  
its beautiful azure-blue colour1 its    
remaining unchanged by exposure to air  
or to fire1 and furnishing us with a    
most valuable pigment1 ,ultramarine1    
more precious than gold6  ,the analysis 
of lapis lazuli represented it to be    
composed of silica1 alumina1 and soda1  
three colourless bodies1 with sulphur   
and a trace of iron4 ,nothing could be  
discovered in it of the nature of a     
pigment1 nothing to which its blue      
colour could be referred1 the cause of  
which was searched for in vain4 ,it     
might therefore have been supposed that 
the analyst was here altogether at      
fault1 and that at any rate its         
artificial production must be           
impossible4 ,nevertheless1 this has been
 accomplished1 and simply by combining  
in the proper proportions1 as determined

 by analysis1 silica1 alumina1 soda1    
iron1 and sulphur4 ,thousands of pounds 
weight are now manufactured from these  
ingredients1 and this artificial        
ultramarine is as beautiful as the      
natural1 while for the price of a single
 ounce of the latter we may obtain many 
pounds of the former4  ,with the        
production of artificial lapis lazuli1  
the formation of mineral bodies by      
synthesis ceased to be a scientific     
problem to the chemist2 he has no longer
 sufficient interest in it to pursue the
 subject4 ,he may now be satisfied that 
analysis will reveal to him the true    
constitution of minerals4 ,but to the   
mineralogist and geologist it is still  
in a great measure an unexplored field1 
offering inquiries of the highest       
interest and importance to their        
pursuits4  ,after becoming acquainted   
with the constituent elements of all the
 substances within our reach and the    
mutual relations of these elements1 the 
remarkable transmutations to which the  

bodies are subject under the influence  
of the vital powers of plants and       
animals1 became the principal object of 
chemical investigations1 and the highest
 point of interest4 ,a new science1     
inexhaustible as life itself1 is here   
presented us1 standing upon the sound   
and solid foundation of a well          
established inorganic chemistry4 ,thus  
the progress of science is1 like the    
development of nature's works1 gradual  
and expansive4 ,after the buds and      
branches spring forth the leaves and    
blossoms1 after the blossoms the fruit4 
,chemistry1 in its application to       
animals and vegetables1 endeavours      
jointly with physiology to enlighten us 
respecting the mysterious processes and 
sources of organic life4     ,,letter   
,,ii   ,my dear ,sir1  ,in my former    
letter ,i reminded you that three of the
 supposed elements of the ancients      
represent the forms or state in which   
all the ponderable matter of our globe  
exists2 ,i would now observe1 that no   

substance possesses absolutely any one  
of those conditions2 that modern        
chemistry recognises nothing            
unchangeably solid1 liquid1 or aeriform3
 means have been devised for effecting a
 change of state in almost every known  
substance4 ,platinum1 alumina1 and rock 
crystal1 it is true1 cannot be liquified
 by the most intense heat of our        
furnaces1 but they melt like wax before 
the flame of the oxy-hydrogen blowpipe4 
,on the other hand1 of the twenty-eight 
gaseous bodies with which we are        
acquainted1 twenty-five may be reduced  
to a liquid state1 and one into a solid4
 ,probably1 ere long1 similar changes of
 condition will be extended to every    
form of matter4  ,there are many things 
relating to this condensation of the    
gases worthy of your attention4 ,most   
aeriform bodies1 when subjected to      
compression1 are made to occupy a space 
which diminishes in the exact ratio of  
the increase of the compressing force4  
,very generally1 under a force double or

 triple of the ordinary atmospheric     
pressure1 they become one half or one   
third their former volume4 ,this was a  
long time considered to be a law1 and   
known as the law of ,marriotte2 but a   
more accurate study of the subject has  
demonstrated that this law is by no     
means of general application4 ,the      
volume of certain gases does not        
decrease in the ratio of the increase of
 the force used to compress them1 but in
 some1 a diminution of their bulk takes 
place in a far greater degree as the    
pressure increases4  ,again1 if         
ammoniacal gas is reduced by a          
compressing force to one-sixth of its   
volume1 or carbonic acid is reduced to  
one thirty-sixth1 a portion of them     
loses entirely the form of a gas1 and   
becomes a liquid1 which1 when the       
pressure is withdrawn1 assumes again in 
an instant its gaseous state--another   
deviation from the law of ,marriotte4   
,our process for reducing gases into    
fluids is of admirable simplicity4 ,a   

simple bent tube1 or a reduction of     
temperature by artificial means1 have   
superseded the powerful compressing     
machines of the early experimenters4    
,the cyanuret of mercury1 when heated in
 an open glass tube1 is resolved into   
cyanogen gas and metallic mercury2 if   
this substance is heated in a tube      
hermetically sealed1 the decomposition  
occurs as before1 but the gas1 unable to
 escape1 and shut up in a space several 
hundred times smaller than it would     
occupy as gas under the ordinary        
atmospheric pressure1 becomes a fluid in
 that part of the tube which is kept    
cool4  ,when sulphuric acid is poured   
upon limestone in an open vessel1       
carbonic acid escapes with effervescence
 as a gas1 but if the decomposition is  
effected in a strong1 close1 and        
suitable vessel of iron1 we obtain the  
carbonic acid in the state of liquid4   
,in this manner it may be obtained in   
considerable quantities1 even many      
pounds weight4 ,carbonic acid is        

separated from other bodies with which  
it is combined as a fluid under a       
pressure of thirty-six atmospheres4     
,the curious properties of fluid        
carbonic acid are now generally known4  
,when a small quantity is permitted to  
escape into the atmosphere1 it assumes  
its gaseous state with extraordinary    
rapidity1 and deprives the remaining    
fluid of caloric so rapidly that it     
congeals into a white crystalline mass  
like snow3 at first1 indeed1 it was     
thought to be really snow1 but upon     
examination it proved to be pure frozen 
carbonic acid4 ,this solid1 contrary to 
expectation1 exercises only a feeble    
pressure upon the surrounding medium4   
,the fluid acid inclosed in a glass tube
 rushes at once1 when opened1 into a    
gaseous state1 with an explosion which  
shatters the tube into fragments2 but   
solid carbonic acid can be handled      
without producing any other effect than 
a feeling of intense cold4 ,the         
particles of the carbonic acid being so 

closely approximated in the solid1 the  
whole force of cohesive attraction      
7which in the fluid is weak7 becomes    
exerted1 and opposes its tendency to    
assume its gaseous state2 but as it     
receives heat from surrounding bodies1  
it passes into gas gradually and without
 violence4 ,the transition of solid     
carbonic acid into gas deprives all     
around it of caloric so rapidly and to  
so great an extent1 that a degree of    
cold is produced immeasurably great1 the
 greatest indeed known4 ,ten1 twenty1 or
 more pounds weight of mercury1 brought 
into contact with a mixture of ether and
 solid carbonic acid1 becomes in a few  
moments firm and malleable4 ,this1      
however1 cannot be accomplished without 
considerable danger4 ,a melancholy      
accident occurred at ,paris1 which will 
probably prevent for the future the     
formation of solid carbonic acid in     
these large quantities1 and deprive the 
next generation of the gratification of 
witnessing these curious experiments4   

,just before the commencement of the    
lecture in the ,laboratory of the       
,polytechnic ,school1 an iron cylinder1 
two feet and a half long and one foot in
 diameter1 in which carbonic acid had   
been developed for experiment before the
 class1 burst1 and its fragments were   
scattered about with the most tremendous
 force2 it cut off both the legs of the 
assistant and killed him on the spot4   
,this vessel1 formed of the strongest   
cast-iron1 and shaped like a cannon1 had
 often been employed to exhibit         
experiments in the presence of the      
students4 ,we can scarcely think1       
without shuddering1 of the dreadful     
calamity such an explosion would have   
occasioned in a hall filled with        
spectators4  ,when we had ascertained   
the fact of gases becoming fluid under  
the influence of cold or pressure1 a    
curious property possessed by charcoal1 
that of absorbing gas to the extent of  
many times its volume1--ten1 twenty1 or 
even as in the case of ammoniacal gas or

 muriatic acid gas1 eighty or ninety    
fold1--which had been long known1 no    
longer remained a mystery4 ,some gases  
are absorbed and condensed within the   
pores of the charcoal1 into a space     
several hundred times smaller than they 
before occupied2 and there is now no    
doubt they there become fluid1 or assume
 a solid state4 ,as in a thousand other 
instances1 chemical action here         
supplants mechanical forces4 ,adhesion  
or heterogeneous attraction1 as it is   
termed1 acquired by this discovery a    
more extended meaning2 it had never     
before been thought of as a cause of    
change of state in matter2 but it is now
 evident that a gas adheres to the      
surface of a solid body by the same     
force which condenses it into a liquid4 
,the smallest amount of a               
gas1--atmospheric air for instance1--can
 be compressed into a space a thousand  
times smaller by mere mechanical        
pressure1 and then its bulk must be to  
the least measurable surface of a solid 

body1 as a grain of sand to a mountain4 
,by the mere effect of mass1--the force 
of gravity1--gaseous molecules are      
attracted by solids and adhere to their 
surfaces2 and when to this physical     
force is added the feeblest chemical    
affinity1 the liquifiable gases cannot  
retain their gaseous state4 ,the amount 
of air condensed by these forces upon a 
square inch of surface is certainly not 
measurable2 but when a solid body1      
presenting several hundred square feet  
of surface within the space of a cubic  
inch1 is brought into a limited volume  
of gas1 we may understand why that      
volume is diminished1 why all gases     
without exception are absorbed4 ,a cubic
 inch of charcoal must have1 at the     
lowest computation1 a surface of one    
hundred square feet4 ,this property of  
absorbing gases varies with different   
kinds of charcoal3 it is possessed in a 
higher degree by those containing the   
most pores1 i4e4 where the pores are    
finer2 and in a lower degree in the more

 spongy kinds1 i4e4 where the pores are 
larger4  ,in this manner every porous   
body--rocks1 stones1 the clods of the   
fields1 c41--imbibe air1 and therefore  
oxygen2 the smallest solid molecule is  
thus surrounded by its own atmosphere of
 condensed oxygen2 and if in their      
vicinity other bodies exist which have  
an affinity for oxygen1 a combination is
 effected4 ,when1 for instance1 carbon  
and hydrogen are thus present1 they are 
converted into nourishment for          
vegetables1--into carbonic acid and     
water4 ,the development of heat when air
 is imbibed1 and the production of steam
 when the earth is moistened by rain1   
are acknowledged to be consequences of  
this condensation by the action of      
surfaces4  ,but the most remarkable and 
interesting case of this kind of action 
is the imbibition of oxygen by metallic 
platinum4 ,this metal1 when massive1 is 
of a lustrous white colour1 but it may  
be brought1 by separating it from its   
solutions1 into so finely divided a     

state1 that its particles no longer     
reflect light1 and it forms a powder as 
black as soot4 ,in this condition it    
absorbs eight hundred times its volume  
of oxygen gas1 and this oxygen must be  
contained within it in a state of       
condensation very like that of fluid    
water4  ,when gases are thus condensed1 
i4e4 their particles made to approximate
 in this extraordinary manner1 their    
properties can be palpably shown4 ,their
 chemical actions become apparent as    
their physical characteristic           
disappears4 ,the latter consists in the 
continual tendency of their particles to
 separate from each other2 and it is    
easy to imagine that this elasticity of 
gaseous bodies is the principal         
impediment to the operation of their    
chemical force2 for this becomes more   
energetic as their particles            
approximate4 ,in that state in which    
they exist within the pores or upon the 
surface of solid bodies1 their repulsion
 ceases1 and their whole chemical action

 is exerted4 ,thus combinations which   
oxygen cannot enter into1 decompositions
 which it cannot effect while in the    
state of gas1 take place with the       
greatest facility in the pores of       
platinum containing condensed oxygen4   
,when a jet of hydrogen gas1 for        
instance1 is thrown upon spongy         
platinum1 it combines with the oxygen   
condensed in the interior of the mass2  
at their point of contact water is      
formed1 and as the immediate consequence
 heat is evolved2 the platinum becomes  
red hot and the gas is inflamed4 ,if we 
interrupt the current of the gas1 the   
pores of the platinum become            
instantaneously filled again with       
oxygen2 and the same phenomenon can be  
repeated a second time1 and so on       
interminably4  ,in finely pulverised    
platinum1 and even in spongy platinum1  
we therefore possess a perpetuum        
mobile--a mechanism like a watch which  
runs out and winds itself up--a force   
which is never exhausted--competent to  

produce effects of the most powerful    
kind1 and self-renewed ad infinitum4    
,many phenomena1 formerly inexplicable1 
are satisfactorily explained by these   
recently discovered properties of porous
 bodies4 ,the metamorphosis of alcohol  
into acetic acid1 by the process known  
as the quick vinegar manufacture1       
depends upon principles1 at a knowledge 
of which we have arrived by a careful   
study of these properties4     ,,letter 
,,iii   ,my dear ,sir1  ,the manufacture
 of soda from common culinary salt1 may 
be regarded as the foundation of all our
 modern improvements in the domestic    
arts2 and we may take it as affording an
 excellent illustration of the          
dependence of the various branches of   
human industry and commerce upon each   
other1 and their relation to chemistry4 
,soda has been used from time immemorial
 in the manufacture of soap and glass1  
two chemical productions which employ   
and keep in circulation an immense      
amount of capital4 ,the quantity of soap

 consumed by a nation would be no       
inaccurate measure whereby to estimate  
its wealth and civilisation4 ,of two    
countries1 with an equal amount of      
population1 the wealthiest and most     
highly civilised will consume the       
greatest weight of soap4 ,this          
consumption does not subserve sensual   
gratification1 nor depend upon fashion1 
but upon the feeling of the beauty1     
comfort1 and welfare1 attendant upon    
cleanliness2 and a regard to this       
feeling is coincident with wealth and   
civilisation4 ,the rich in the middle   
ages concealed a want of cleanliness in 
their clothes and persons under a       
profusion of costly scents and essences1
 whilst they were more luxurious in     
eating and drinking1 in apparel and     
horses4 ,with us a want of cleanliness  
is equivalent to insupportable misery   
and misfortune4  ,soap belongs to those 
manufactured products1 the money value  
of which continually disappears from    
circulation1 and requires to be         

continually renewed4 ,it is one of the  
few substances which are entirely       
consumed by use1 leaving no product of  
any worth4 ,broken glass and bottles are
 by no means absolutely worthless2 for  
rags we may purchase new cloth1 but     
soap-water has no value whatever4 ,it   
would be interesting to know accurately 
the amount of capital involved in the   
manufacture of soap2 it is certainly as 
large as that employed in the coffee    
trade1 with this important difference as
 respects ,germany1 that it is entirely 
derived from our own soil4  ,france     
formerly imported soda from             
,spain1--,spanish sodas being of the    
best quality--at an annual expenditure  
of twenty to thirty millions of francs4 
,during the war with ,england the price 
of soda1 and consequently of soap and   
glass1 rose continually2 and all        
manufactures suffered in consequence4   
,the present method of making soda from 
common salt was discovered by ,le ,blanc
 at the end of the last century4 ,it was

 a rich boon for ,france1 and became of 
the highest importance during the wars  
of ,napoleon4 ,in a very short time it  
was manufactured to an extraordinary    
extent1 especially at the seat of the   
soap manufactories4 ,marseilles         
possessed for a time a monopoly of soda 
and soap4 ,the policy of ,napoleon      
deprived that city of the advantages    
derived from this great source of       
commerce1 and thus excited the hostility
 of the population to his dynasty1 which
 became favourable to the restoration of
 the ,bourbons4 ,a curious result of an 
improvement in a chemical manufacture6  
,it was not long1 however1 in reaching  
,england4  ,in order to prepare the soda
 of commerce 7which is the carbonate7   
from common salt1 it is first converted 
into ,glauber's salt 7sulphate of soda74
 ,for this purpose #hj pounds weight of 
concentrated sulphuric acid 7oil of     
vitriol7 are required to #ajj pounds of 
common salt4 ,the duty upon salt        
checked1 for a short time1 the full     

advantage of this discovery2 but when   
the ,government repealed the duty1 and  
its price was reduced to its minimum1   
the cost of soda depended upon that of  
sulphuric acid4  ,the demand for        
sulphuric acid now increased to an      
immense extent2 and1 to supply it1      
capital was embarked abundantly1 as it  
afforded an excellent remuneration4 ,the
 origin and formation of sulphuric acid 
was studied most carefully2 and from    
year to year1 better1 simpler1 and      
cheaper methods of making it were       
discovered4 ,with every improvement in  
the mode of manufacture1 its price fell2
 and its sale increased in an equal     
ratio4  ,sulphuric acid is now          
manufactured in leaden chambers1 of such
 magnitude that they would contain the  
whole of an ordinary-sized house4 ,as   
regards the process and the apparatus1  
this manufacture has reached its        
acme--scarcely is either susceptible of 
improvement4 ,the leaden plates of which
 the chambers are constructed1 requiring

 to be joined together with lead 7since 
tin or solder would be acted on by the  
acid71 this process was1 until lately1  
as expensive as the plates themselves2  
but now1 by means of the oxy-hydrogen   
blowpipe1 the plates are cemented       
together at their edges by mere fusion1 
without the intervention of any kind of 
solder4  ,and then1 as to the process3  
according to theory1 #ajj pounds weight 
of sulphur ought to produce #cjf pounds 
of sulphuric acid2 in practice #cjj     
pounds are actually obtained2 the amount
 of loss is therefore too insignificant 
for consideration4  ,again2 saltpetre   
being indispensable in making sulphuric 
acid1 the commercial value of that salt 
had formerly an important influence upon
 its price4 ,it is true that #ajj pounds
 of saltpetre only are required to #ajjj
 pounds of sulphur2 but its cost was    
four times greater than an equal weight 
of the latter4  ,travellers had observed
 near the small seaport of ,yquiqui1 in 
the district of ,atacama1 in ,peru1 an  

efflorescence covering the ground over  
extensive districts4 ,this was found to 
consist principally of nitrate of soda4 
,advantage was quickly taken of this    
discovery4 ,the quantity of this        
valuable salt proved to be              
inexhaustible1 as it exists in beds     
extending over more than #bjj square    
miles4 ,it was brought to ,england at   
less than half the freight of the ,east 
,india saltpetre 7nitrate of potassa72  
and as1 in the chemical manufacture     
neither the potash nor the soda were    
required1 but only the nitric acid1 in  
combination with the alkali1 the        
soda-saltpetre of ,south ,america soon  
supplanted the potash-nitre of the      
,east4 ,the manufacture of sulphuric    
acid received a new impulse2 its price  
was much diminished without injury to   
the manufacturer2 and1 with the         
exception of fluctuations caused by the 
impediments thrown in the way of the    
export of sulphur from ,sicily1 it soon 
became reduced to a minimum1 and        

remained stationary4  ,potash-saltpetre 
is now only employed in the manufacture 
of gunpowder2 it is no longer in demand 
for other purposes2 and thus1 if        
,government effect a saving of many     
hundred thousand pounds annually in     
gunpowder1 this economy must be         
attributed to the increased manufacture 
of sulphuric acid4  ,we may form an idea
 of the amount of sulphuric acid        
consumed1 when we find that #ej1jjj     
pounds weight are made by a small       
manufactory1 and from #bjj1jjj to       
#fjj1jjj pounds by a large one annually4
 ,this manufacture causes immense sums  
to flow annually into ,sicily4 ,it has  
introduced industry and wealth into the 
arid and desolate districts of ,atacama4
 ,it has enabled us to obtain platina   
from its ores at a moderate and yet     
remunerating price2 since the vats      
employed for concentrating this acid are
 constructed of this metal1 and cost    
from #ajjjl4 to #bjjjl4 sterling4 ,it   
leads to frequent improvements in the   

manufacture of glass1 which continually 
becomes cheaper and more beautiful4 ,it 
enables us to return to our fields all  
their potash--a most valuable and       
important manure--in the form of ashes1 
by substituting soda in the manufacture 
of glass and soap4  ,it is impossible to
 trace1 within the compass of a letter1 
all the ramifications of this tissue of 
changes and improvements resulting from 
one chemical manufacture2 but ,i must   
still claim your attention to a few more
 of its most important and immediate    
results4 ,i have already told you1 that 
in the manufacture of soda from culinary
 salt1 it is first converted into       
sulphate of soda4 ,in this first part of
 the process1 the action of sulphuric   
acid produces muriatic acid to the      
extent of one-and-a-half the amount of  
the sulphuric acid employed4 ,at first1 
the profit upon the soda was so great1  
that no one took the trouble to collect 
the muriatic acid3 indeed it had no     
commercial value4 ,a profitable         

application of it was1 however1 soon    
discovered3 it is a compound of         
chlorine1 and this substance may be     
obtained from it purer than from any    
other source4 ,the bleaching power of   
chlorine has long been known2 but it was
 only employed upon a large scale after 
it was obtained from this residuary     
muriatic acid1 and it was found that in 
combination with lime it could be       
transported to distances without        
inconvenience4 ,thenceforth it was used 
for bleaching cotton2 and1 but for this 
new bleaching process1 it would scarcely
 have been possible for the cotton      
manufacture of ,great ,britain to have  
attained its present enormous           
extent1--it could not have competed in  
price with ,france and ,germany4 ,in the
 old process of bleaching1 every piece  
must be exposed to the air and light    
during several weeks in the summer1 and 
kept continually moist by manual labour4
 ,for this purpose1 meadow land1        
eligibly situated1 was essential4 ,now a

 single establishment near ,glasgow     
bleaches #adjj pieces of cotton daily1  
throughout the year4 ,what an enormous  
capital would be required to purchase   
land for this purpose6 ,how greatly     
would it increase the cost of bleaching 
to pay interest upon this capital1 or to
 hire so much land in ,england6 ,this   
expense would scarcely have been felt in
 ,germany4 ,besides the diminished      
expense1 the cotton stuffs bleached with
 chlorine suffer less in the hands of   
skilful workmen than those bleached in  
the sun2 and already the peasantry in   
some parts of ,germany have adopted it1 
and find it advantageous4  ,another use 
to which cheap muriatic acid is applied1
 is the manufacture of glue from bones4 
,bone contains from #cj to #cf per cent4
 of earthy matter--chiefly phosphate of 
lime1 and the remainder is gelatine4    
,when bones are digested in muriatic    
acid they become transparent and        
flexible like leather1 the earthy matter
 is dissolved1 and after the acid is all

 carefully washed away1 pieces of glue  
of the same shape as the bones remain1  
which are soluble in hot water and      
adapted to all the purposes of ordinary 
glue1 without further preparation4      
,another important application of       
sulphuric acid may be adduced2 namely1  
to the refining of silver and the       
separation of gold1 which is always     
present in some proportion in native    
silver4 ,silver1 as it is usually       
obtained from mines in ,europe1 contains
 in #af ounces1 #f to #h ounces of      
copper4 ,when used by the silversmith1  
or in coining1 #af ounces must contain  
in ,germany #ac ounces of silver1 in    
,england about #ad #a_/b4 ,but this     
alloy is always made artificially by    
mixing pure silver with the due         
proportion of the copper2 and for this  
purpose the silver must be obtained pure
 by the refiner4 ,this he formerly      
effected by amalgamation1 or by roasting
 it with lead2 and the cost of this     
process was about #bl4 for every        

hundred-weight of silver4 ,in the silver
 so prepared1 about #a_/abjj to         
#a_/bjjjth part of gold remained2 to    
effect the separation of this by        
nitrio-hydrochloric acid was more       
expensive than the value of the gold2 it
 was therefore left in utensils1 or     
circulated in coin1 valueless4 ,the     
copper1 too1 of the native silver was no
 use whatever4 ,but the #a_/ajjjth part 
of gold1 being about one and a half per 
cent4 of the value of the silver1 now   
covers the cost of refining1 and affords
 an adequate profit to the refiner2 so  
that he effects the separation of the   
copper1 and returns to his employer the 
whole amount of the pure silver1 as well
 as the copper1 without demanding any   
payment3 he is amply remunerated by that
 minute portion of gold4 ,the new       
process of refining is a most beautiful 
chemical operation3 the granulated metal
 is boiled in concentrated sulphuric    
acid1 which dissolves both the silver   
and the copper1 leaving the gold nearly 

pure1 in the form of a black powder4    
,the solution is then placed in a leaden
 vessel containing metallic copper2 this
 is gradually dissolved1 and the silver 
precipitated in a pure metallic state4  
,the sulphate of copper thus formed is  
also a valuable product1 being employed 
in the manufacture of green and blue    
pigments4  ,other immediate results of  
the economical production of sulphuric  
acid1 are the general employment of     
phosphorus matches1 and of stearine     
candles1 that beautiful substitute for  
tallow and wax4 ,twenty-five years ago1 
the present prices and extensive        
applications of sulphuric and muriatic  
acids1 of soda1 phosphorus1 c41 would   
have been considered utterly impossible4
 ,who is able to foresee what new and   
unthought-of chemical productions1      
ministering to the service and comforts 
of mankind1 the next twenty-five years  
may produce8  ,after these remarks you  
will perceive that it is no exaggeration
 to say1 we may fairly judge of the     

commercial prosperity of a country from 
the amount of sulphuric acid it         
consumes4 ,reflecting upon the important
 influence which the price of sulphur   
exercises upon the cost of production of
 bleached and printed cotton stuffs1    
soap1 glass1 c41 and remembering that   
,great ,britain supplies ,america1      
,spain1 ,portugal1 and the ,east1 with  
these1 exchanging them for raw cotton1  
silk1 wine1 raisins1 indigo1 c41 c41 we 
can understand why the ,english         
,government should have resolved to     
resort to war with ,naples1 in order to 
abolish the sulphur monopoly1 which the 
latter power attempted recently to      
establish4 ,nothing could be more       
opposed to the true interests of ,sicily
 than such a monopoly2 indeed1 had it   
been maintained a few years1 it is      
highly probable that sulphur1 the source
 of her wealth1 would have been rendered
 perfectly valueless to her4 ,science   
and industry form a power to which it is
 dangerous to present impediments4 ,it  

was not difficult to perceive that the  
issue would be the entire cessation of  
the exportation of sulphur from ,sicily4
 ,in the short period the sulphur       
monopoly lasted1 fifteen patents were   
taken out for methods to obtain back the
 sulphuric acid used in making soda4    
,admitting that these fifteen           
experiments were not perfectly          
successful1 there can be no doubt it    
would ere long have been accomplished4  
,but then1 in gypsum1 7sulphate of      
lime71 and in heavy-spar1 7sulphate of  
barytes71 we possess mountains of       
sulphuric acid2 in galena1 7sulphate of 
lead71 and in iron pyrites1 we have no  
less abundance of sulphur4 ,the problem 
is1 how to separate the sulphuric acid1 
or the sulphur1 from these native       
stores4 ,hundreds of thousands of pounds
 weight of sulphuric acid were prepared 
from iron pyrites1 while the high price 
of sulphur consequent upon the monopoly 
lasted4 ,we should probably ere long    
have triumphed over all difficulties1   

and have separated it from gypsum4 ,the 
impulse has been given1 the possibility 
of the process proved1 and it may happen
 in a few years that the inconsiderate  
financial speculation of ,naples may    
deprive her of that lucrative commerce4 
,in like manner ,russia1 by her         
prohibitory system1 has lost much of her
 trade in tallow and potash4 ,one       
country purchases only from absolute    
necessity from another1 which excludes  
her own productions from her markets4   
,instead of the tallow and linseed oil  
of ,russia1 ,great ,britain now uses    
palm oil and cocoa-nut oil of other     
countries4 ,precisely analogous is the  
combination of workmen against their    
employers1 which has led to the         
construction of many admirable machines 
for superseding manual labour4 ,in      
commerce and industry every imprudence  
carries with it its own punishment2     
every oppression immediately and        
sensibly recoils upon the head of those 
from whom it emanates4     ,,letter ,,iv

   ,my dear ,sir1  ,one of the most     
influential causes of improvement in the
 social condition of mankind is that    
spirit of enterprise which induces men  
of capital to adopt and carry out       
suggestions for the improvement of      
machinery1 the creation of new articles 
of commerce1 or the cheaper production  
of those already in demand2 and we      
cannot but admire the energy with which 
such men devote their talents1 their    
time1 and their wealth1 to realise the  
benefits of the discoveries and         
inventions of science4 ,for even when   
these are expended upon objects wholly  
incapable of realisation1--nay1 even    
when the idea which first gave the      
impulse proves in the end to be         
altogether impracticable or absurd1     
immediate good to the community         
generally ensues2 some useful and       
perhaps unlooked-for result flows       
directly1 or springs ultimately1 from   
exertions frustrated in their main      
design4 ,thus it is also in the pursuit 

of science4 ,theories lead to           
experiments and investigations2 and he  
who investigates will scarcely ever fail
 of being rewarded by discoveries4 ,it  
may be1 indeed1 the theory sought to be 
established is entirely unfounded in    
nature2 but while searching in a right  
spirit for one thing1 the inquirer may  
be rewarded by finding others far more  
valuable than those which he sought4    
,at the present moment1                 
electro-magnetism1 as a moving power1 is
 engaging great attention and study2    
wonders are expected from its           
application to this purpose4 ,according 
to the sanguine expectations of many    
persons1 it will shortly be employed to 
put into motion every kind of machinery1
 and amongst other things it will be    
applied to impel the carriages of       
railroads1 and this at so small a cost1 
that expense will no longer be matter of
 consideration4 ,england is to lose her 
superiority as a manufacturing country1 
inasmuch as her vast store of coals will

 no longer avail her as an economical   
source of motive power4 ,we1 say the    
,german cultivators of this science1    
have cheap zinc1 and1 how small a       
quantity of this metal is required to   
turn a lathe1 and consequently to give  
motion to any kind of machinery6  ,such 
expectations may be very attractive1 and
 yet they are altogether illusory6 they 
will not bear the test of a few simple  
calculations2 and these our friends have
 not troubled themselves to institute4  
,with a simple flame of spirits of wine1
 under a proper vessel containing       
boiling water1 a small carriage of #bjj 
to #cjj pounds weight can be put into   
motion1 or a weight of #hj to #ajj      
pounds may be raised to a height of #bj 
feet4 ,the same effects may be produced 
by dissolving zinc in dilute sulphuric  
acid in a certain apparatus4 ,this is   
certainly an astonishing and highly     
interesting discovery2 but the question 
to be determined is1 which of the two   
processes is the least expensive8  ,in  

order to answer this question1 and to   
judge correctly of the hopes entertained
 from this discovery1 let me remind you 
of what chemists denominate equivalents4
 ,these are certain unalterable ratios  
of effects which are proportionate to   
each other1 and may therefore be        
expressed in numbers4 ,thus1 if we      
require #h pounds of oxygen to produce a
 certain effect1 and we wish to employ  
chlorine for the same effect1 we must   
employ neither more nor less than #ce   
#a_/b pounds weight4 ,in the same       
manner1 #f pounds weight of coal are    
equivalent to #cb pounds weight of zinc4
 ,the numbers representing chemical     
equivalents express very general ratios 
of effects1 comprehending for all bodies
 all the actions they are capable of    
producing4  ,if zinc be combined in a   
certain manner with another metal1 and  
submitted to the action of dilute       
sulphuric acid1 it is dissolved in the  
form of an oxide2 it is in fact burned  
at the expense of the oxygen contained  

in the fluid4 ,a consequence of this    
action is the production of an electric 
current1 which1 if conducted through a  
wire1 renders it magnetic4 ,in thus     
effecting the solution of a pound       
weight1 for example1 of zinc1 we obtain 
a definite amount of force adequate to  
raise a given weight one inch1 and to   
keep it suspended2 and the amount of    
weight it will be capable of suspending 
will be the greater the more rapidly the
 zinc is dissolved4  ,by alternately    
interrupting and renewing the contact of
 the zinc with the acid1 and by very    
simple mechanical arrangements1 we can  
give to the iron an upward and downward 
or a horizontal motion1 thus producing  
the conditions essential to the motion  
of any machinery4  ,this moving force is
 produced by the oxidation of the zinc2 
and1 setting aside the name given to the
 force in this case1 we know that it can
 be produced in another manner4 ,if we  
burn the zinc under the boiler of a     
steam-engine1 consequently in the oxygen

 of the air instead of the galvanic     
pile1 we should produce steam1 and by it
 a certain amount of force4 ,if we      
should assume1 7which1 however1 is not  
proved17 that the quantity of force is  
unequal in these cases1--that1 for      
instance1 we had obtained double or     
triple the amount in the galvanic pile1 
or that in this mode of generating force
 less loss is sustained1--we must still 
recollect the equivalents of zinc and   
coal1 and make these elements of our    
calculation4 ,according to the          
experiments of ,despretz1 #f pounds     
weight of zinc1 in combining with       
oxygen1 develops no more heat than #a   
pound of coal2 consequently1 under equal
 conditions1 we can produce six times   
the amount of force with a pound of coal
 as with a pound of zinc4 ,it is        
therefore obvious that it would be more 
advantageous to employ coal instead of  
zinc1 even if the latter produced four  
times as much force in a galvanic pile1 
as an equal weight of coal by its       

combustion under a boiler4 ,indeed it is
 highly probable1 that if we burn under 
the boiler of a steam-engine the        
quantity of coal required for smelting  
the zinc from its ores1 we shall produce
 far more force than the whole of the   
zinc so obtained could originate in any 
form of apparatus whatever4  ,heat1     
electricity1 and magnetism1 have a      
similar relation to each other as the   
chemical equivalents of coal1 zinc1 and 
oxygen4 ,by a certain measure of        
electricity we produce a corresponding  
proportion of heat or of magnetic power2
 we obtain that electricity by chemical 
affinity1 which in one shape produces   
heat1 in another electricity or         
magnetism4 ,a certain amount of affinity
 produces an equivalent of electricity  
in the same manner as1 on the other     
hand1 we decompose equivalents of       
chemical compounds by a definite measure
 of electricity4 ,the magnetic force of 
the pile is therefore limited to the    
extent of the chemical affinity1 and in 

the case before us is obtained by the   
combination of the zinc and sulphuric   
acid4 ,in the combustion of coal1 the   
heat results from1 and is measured by1  
the affinity of the oxygen of the       
atmosphere for that substance4  ,it is  
true that with a very small expense of  
zinc1 we can make an iron wire a magnet 
capable of sustaining a thousand pounds 
weight of iron2 let us not allow        
ourselves to be misled by this4 ,such a 
magnet could not raise a single pound   
weight of iron two inches1 and therefore
 could not impart motion4 ,the magnet   
acts like a rock1 which while at rest   
presses with a weight of a thousand     
pounds upon a basis2 it is like an      
inclosed lake1 without an outlet and    
without a fall4 ,but it may be said1 we 
have1 by mechanical arrangements1 given 
it an outlet and a fall4 ,true2 and this
 must be regarded as a great triumph of 
mechanics2 and ,i believe it is         
susceptible of further improvements1 by 
which greater force may be obtained4    

,but with every conceivable advantage of
 mechanism1 no one will dispute that one
 pound of coal1 under the boiler of a   
steam-engine1 will give motion to a mass
 several hundred times greater than a   
pound of zinc in the galvanic pile4     
,our experience of the employment of    
electro-magnetism as a motory power is1 
however1 too recent to enable us to     
foresee the ultimate results of         
contrivances to apply it2 and1          
therefore1 those who have devoted       
themselves to solve the problem of its  
application should not be discouraged1  
inasmuch as it would undoubtedly be a   
most important achievement to supersede 
the steam-engine1 and thus escape the   
danger of railroads1 even at double     
their expense4  ,professor ,weber of    
,gottingen has thrown out a suggestion1 
that if a contrivance could be devised  
to enable us to convert at will the     
wheels of the steam-carriage into       
magnets1 we should be enabled to ascend 
and descend acclivities with great      

facility4 ,this notion may ultimately   
be1 to a certain extent1 realised4  ,the
 employment of the galvanic pile as a   
motory power1 however1 must1 like every 
other contrivance1 depend upon the      
question of its relative economy3       
probably some time hence it may so far  
succeed as to be adopted in certain     
favourable localities2 it may stand in  
the same relation to steam power as the 
manufacture of beet sugar bears to that 
of cane1 or as the production of gas    
from oils and resins to that from       
mineral coal4  ,the history of beet-root
 sugar affords us an excellent          
illustration of the effect of prices    
upon commercial productions4 ,this      
branch of industry seems at length1 as  
to its processes1 to be perfected4 ,the 
most beautiful white sugar is now       
manufactured from the beet-root1 in the 
place of the treacle-like sugar1 having 
the taste of the root1 which was first  
obtained2 and instead of #c or #d per   
cent41 the proportion obtained by       

,achard1 double or even treble that     
amount is now produced4 ,and            
notwithstanding the perfection of the   
manufacture1 it is probable it will ere 
long be in most places entirely         
discontinued4 ,in the years #ahbd to    
#ahbg1 the prices of agricultural       
produce were much lower than at present1
 while the price of sugar was the same4 
,at that time one malter #a of wheat was
 #ajs41 and one klafter #b of wood      
#ahs41 and land was falling in price4   
,thus1 food and fuel were cheap1 and the
 demand for sugar unlimited2 it was1    
therefore1 advantageous to grow         
beet-root1 and to dispose of the produce
 of land as sugar4 ,all these           
circumstances are now different4 ,a     
malter of wheat costs #ahs42 a klafter  
of wood1 #cjs4 to #cfs4 ,wages have     
risen1 but not in proportion1 whilst the
 price of colonial sugar has fallen4    
,within the limits of the ,german       
commercial league1 as1 for instance1 at 
,frankfort-on-the-,maine1 a pound of the

 whitest and best loaf sugar is #g;d42  
the import duty is #ca_/;d41 or #cjs4   
per cwt41 leaving #ca_/;d4 as the price 
of the sugar4 ,in the year #ahbg1 then1 
one malter of wheat was equal to #dj    
lbs4 weight of sugar1 whilst at present 
that quantity of wheat is worth #gj lbs4
 of sugar4 ,if indeed fuel were the same
 in price as formerly1 and #gj lbs4 of  
sugar could be obtained from the same   
quantity of the root as then yielded #dj
 lbs41 it might still be advantageously 
produced2 but the amount1 if now        
obtained by the most approved methods of
 extraction1 falls far short of this2   
and as fuel is double the price1 and    
labour dearer1 it follows that1 at      
present1 it is far more advantageous to 
cultivate wheat and to purchase sugar4  
,there are1 however1 other elements     
which must enter into our calculations2 
but these serve to confirm our          
conclusion that the manufacture of      
beet-root sugar as a commercial         
speculation must cease4 ,the leaves and 

residue of the root1 after the juice was
 expressed1 were used as food for       
cattle1 and their value naturally       
increased with the price of grain4 ,by  
the process formerly pursued1 #ge lbs4  
weight of juice were obtained from #ajj 
lbs4 of beet-root1 and gave #e lbs4 of  
sugar4 ,the method of ,schutzenbach1    
which was eagerly adopted by the        
manufacturers1 produced from the same   
quantity of root #h lbs4 of sugar2 but  
it was attended with more expense to    
produce1 and the loss of the residue as 
food for cattle4 ,the increased expense 
in this process arises from the larger  
quantity of fuel required to evaporate  
the water2 for instead of merely        
evaporating the juice1 the dry residue  
is treated with water1 and we require   
fuel sufficient to evaporate #ajf lbs4  
of fluid instead of #ge lbs41 and the   
residue is only fit for manure4 ,the    
additional #c lbs4 of sugar are         
purchased at the expense of much fuel1  
and the loss of the residue as an       

article of food4  ,if the valley of the 
,rhine possessed mines of diamonds as   
rich as those of ,golconda1 ,visiapoor1 
or the ,brazils1 they would probably not
 be worth the working3 at those places  
the cost of extraction is #bhs4 to #cjs4
 the carat4 ,with us it amounts to three
 or four times as much--to more1 in     
fact1 than diamonds are worth in the    
market4 ,the sand of the ,rhine contains
 gold2 and in the ,grand ,duchy of      
,baden many persons are occupied in     
gold-washing when wages are low2 but as 
soon as they rise1 this employment      
ceases4 ,the manufacture of sugar from  
beet-root1 in the like manner1 twelve to
 fourteen years ago offered advantages  
which are now lost3 instead1 therefore1 
of maintaining it at a great sacrifice1 
it would be more reasonable1 more in    
accordance with true natural economy1 to
 cultivate other and more valuable      
productions1 and with them purchase     
sugar4 ,not only would the state be the 
gainer1 but every member of the         

community4 ,this argument does not      
apply1 perhaps1 to ,france and ,bohemia1
 where the prices of fuel and of        
colonial sugar are very different to    
those in ,germany4  ,the manufacture of 
gas for lighting1 from coal1 resin1 and 
oils1 stands with us on the same barren 
ground4  ,the price of the materials    
from which gas is manufactured in       
,england bears a direct proportion to   
the price of corn3 there the cost of    
tallow and oil is twice as great as in  
,germany1 but iron and coal are         
two-thirds cheaper2 and even in ,england
 the manufacture of gas is only         
advantageous when the other products of 
the distillation of coal1 the coke1 c41 
can be sold4  ,it would certainly be    
esteemed one of the greatest discoveries
 of the age if any one could succeed in 
condensing coal gas into a white1 dry1  
solid1 odourless substance1 portable1   
and capable of being placed upon a      
candlestick1 or burned in a lamp4 ,wax1 
tallow1 and oil1 are combustible gases  

in a solid or fluid form1 which offer   
many advantages for lighting1 not       
possessed by gas3 they furnish1 in      
well-constructed lamps1 as much light1  
without requiring the expensive         
apparatus necessary for the combustion  
of gas1 and they are generally more     
economical4 ,in large towns1 or such    
establishments as hotels1 where coke is 
in demand1 and where losses in stolen   
tallow or oil must be considered1       
together with the labour of snuffing    
candles and cleaning lamps1 the higher  
price of gas is compensated4 ,in places 
where gas can be manufactured from      
resin1 oil of turpentine1 and other     
cheap oils1 as at ,frankfort1 this is   
advantageous so long as it is pursued on
 small scale only4 ,if large towns were 
lighted in the same manner1 the         
materials would rise in price3 the whole
 amount at present produced would       
scarcely suffice for two such towns as  
,berlin and ,munich4 ,but no just       
calculation can be made from the present

 prices of turpentine1 resin1 c41 which 
are not produced upon any large scale4  
,footnote #a3 ,malter--a measure        
containing several bushels1 but varying 
in different countries4  ,footnote #b3  
,klafter--a cord1 a stack1 measuring six
 feet every way4     ,,letter ,v   ,my  
dear ,sir1  ,until very recently it was 
supposed that the physical qualities of 
bodies1 i4e4 hardness1 colour1 density1 
transparency1 c41 and still more their  
chemical properties1 must depend upon   
the nature of their elements1 or upon   
their composition4 ,it was tacitly      
received as a principle1 that two bodies
 containing the same elements in the    
same proportion1 must of necessity      
possess the same properties4 ,we could  
not imagine an exact identity of        
composition giving rise to two bodies   
entirely different in their sensible    
appearance and chemical relations4 ,the 
most ingenious philosophers entertained 
the opinion that chemical combination is
 an inter-penetration of the particles  

of different kinds of matter1 and that  
all matter is susceptible of infinite   
division4 ,this has proved to be        
altogether a mistake4 ,if matter were   
infinitely divisible in this sense1 its 
particles must be imponderable1 and a   
million of such molecules could not     
weigh more than an infinitely small one4
 ,but the particles of that imponderable
 matter1 which1 striking upon the       
retina1 give us the sensation of light1 
are not in a mathematical sense         
infinitely small4  ,inter-penetration of
 elements in the production of a        
chemical compound1 supposes two distinct
 bodies1 ,a and ,b1 to occupy one and   
the same space at the same time4 ,if    
this were so1 different properties could
 not consist with an equal and identical
 composition4  ,that hypothesis1        
however1 has shared the fate of         
innumerable imaginative explanations of 
natural phenomena1 in which our         
predecessors indulged4 ,they have now no
 advocate4 ,the force of truth1         

dependent upon observation1 is          
irresistible4 ,a great many substances  
have been discovered amongst organic    
bodies1 composed of the same elements in
 the same relative proportions1 and yet 
exhibiting physical and chemical        
properties perfectly distinct one from  
another4 ,to such substances the term   
,isomeric 7from #a_/;ao#a_/ equal and   
aei#a_/o#a_/ part7 is applied4 ,a great 
class of bodies1 known as the volatile  
oils1 oil of turpentine1 essence of     
lemons1 oil of balsam of copaiba1 oil of
 rosemary1 oil of juniper1 and many     
others1 differing widely from each other
 in their odour1 in their medicinal     
effects1 in their boiling point1 in     
their specific gravity1 c41 are exactly 
identical in composition1--they contain 
the same elements1 carbon and hydrogen1 
in the same proportions4  ,how admirably
 simple does the chemistry of organic   
nature present itself to us from this   
point of view6 ,an extraordinary variety
 of compound bodies produced with equal 

weights of two elements6 and how wide   
their dissimilarity6 ,the crystallised  
part of the oil of roses1 the delicious 
fragrance of which is so well known1 a  
solid at ordinary temperatures1 although
 readily volatile1 is a compound body   
containing exactly the same elements1   
and in the same proportions1 as the gas 
we employ for lighting our streets2 and1
 in short1 the same elements1 in the    
same relative quantities1 are found in a
 dozen other compounds1 all differing   
essentially in their physical and       
chemical properties4  ,these remarkable 
truths1 so highly important in their    
applications1 were not received and     
admitted as sufficiently established1   
without abundant proofs4 ,many examples 
have long been known where the analysis 
of two different bodies gave the same   
composition2 but such cases were        
regarded as doubtful3 at any rate1 they 
were isolated observations1 homeless in 
the realms of science3 until1 at length1
 examples were discovered of two or more

 bodies whose absolute identity of      
composition1 with totally distinct      
properties1 could be demonstrated in a  
more obvious and conclusive manner than 
by mere analysis2 that is1 they can be  
converted and reconverted into each     
other without addition and without      
subtraction4  ,in cyanuric acid1        
hydrated cyanic acid1 and cyamelide1 we 
have three such isomeric compounds4     
,cyanuric acid is crystalline1 soluble  
in water1 and capable of forming salts  
with metallic oxides4  ,hydrated cyanic 
acid is a volatile and highly blistering
 fluid1 which cannot be brought into    
contact with water without being        
instantaneously decomposed4  ,cyamelide 
is a white substance very like          
porcelain1 absolutely insoluble in      
water4  ,now if we place the            
first1--cyanuric acid1--in a vessel     
hermetically sealed1 and apply a high   
degree of heat1 it is converted by its  
influence into hydrated cyanic acid2    
and1 then1 if this is kept for some time

 at the common temperature1 it passes   
into cyamelide1 no other element being  
present4 ,and1 again inversely1         
cyamelide can be converted into cyanuric
 acid and hydrated cyanic acid4  ,we    
have three other bodies which pass      
through similar changes1 in aldehyde1   
metaldehyde1 and etaldehyde2 and1 again 
two1 in urea and cyanuret of ammonia4   
,further1 #ajj parts of aldehyde        
hydrated butyric acid and acetic ether  
contain the same elements in the same   
proportion4 ,thus one substance may be  
converted into another without addition 
or subtraction1 and without the         
participation of any foreign bodies in  
the change4  ,the doctrine that matter  
is not infinitely divisible1 but on the 
contrary1 consists of atoms incapable of
 further division1 alone furnishes us   
with a satisfactory explanation of these
 phenomena4 ,in chemical combinations1  
the ultimate atoms of bodies do not     
penetrate each other1 they are only     
arranged side by side in a certain      

order1 and the properties of the        
compound depend entirely upon this      
order4 ,if they are made to change their
 place--their mode of arrangement--by an
 impulse from without1 they combine     
again in a different manner1 and another
 compound is formed with totally        
different properties4 ,we may suppose   
that one atom combines with one atom of 
another element to form a compound atom1
 while in other bodies two and two1 four
 and four1 eight and eight1 are united2 
so that in all such compounds the amount
 per cent4 of the elements is absolutely
 equal2 and yet their physical and      
chemical properties must be totally     
different1 the constitution of each atom
 being peculiar1 in one body consisting 
of two1 in another of four1 in a third  
of eight1 and in a fourth of sixteen    
simple atoms4  ,the discovery of these  
facts immediately led to many most      
beautiful and interesting results2 they 
furnished us with a satisfactory        
explanation of observations which were  

before veiled in mystery1--a key to many
 of ,nature's most curious recesses4    
,again2 solid bodies1 whether simple or 
compound1 are capable of existing in two
 states1 which are known by the terms   
amorphous and crystalline4  ,when matter
 is passing from a gaseous or liquid    
state slowly into a solid1 an incessant 
motion is observed1 as if the molecules 
were minute magnets2 they are seen to   
repel each other in one direction1 and  
to attract and cohere together in       
another1 and in the end become arranged 
into a regular form1 which under equal  
circumstances is always the same for any
 given kind of matter2 that is1 crystals
 are formed4  ,time and freedom of      
motion for the particles of bodies are  
necessary to the formation of crystals4 
,if we force a fluid or a gas to become 
suddenly solid1 leaving no time for its 
particles to arrange themselves1 and    
cohere in that direction in which the   
cohesive attraction is strongest1 no    
crystals will be formed1 but the        

resulting solid will have a different   
colour1 a different degree of hardness  
and cohesion1 and will refract light    
differently2 in one word1 will be       
amorphous4 ,thus we have cinnabar as a  
red and a jet-black substance2 sulphur a
 fixed and brittle body1 and soft1      
semitransparent1 and ductile2 glass as a
 milk-white opaque substance1 so hard   
that it strikes fire with steel1 and in 
its ordinary and well-known state4      
,these dissimilar states and properties 
of the same body are occasioned in one  
case by a regular1 in the other by an   
irregular1 arrangement of its atoms2 one
 is crystalline1 the other amorphous4   
,applying these facts to natural        
productions1 we have reason to believe  
that clay-slate1 and many kinds of      
greywacke1 are amorphous feldspar1 as   
transition limestone is amorphous       
marble1 basalt and lava mixtures of     
amorphous zeolite and augite4 ,anything 
that influences the cohesion1 must also 
in a certain degree alter the properties

 of bodies4 ,carbonate of lime1 if      
crystallised at ordinary temperatures1  
possesses the crystalline form1         
hardness1 and refracting power of common
 spar2 if crystallised at a higher      
temperature1 it has the form and        
properties of arragonite4  ,finally1    
,isomorphism1 or the equality of form of
 many chemical compounds having a       
different composition1 tends to prove   
that matter consists of atoms the mere  
arrangement of which produces all the   
properties of bodies4 ,but when we find 
that a different arrangement of the same
 elements gives rise to various physical
 and chemical properties1 and a similar 
arrangement of different elements       
produces properties very much the same1 
may we not inquire whether some of those
 bodies which we regard as elements may 
not be merely modifications of the same 
substance8--whether they are not the    
same matter in a different state of     
arrangement8 ,we know in fact the       
existence of iron in two states1 so     

dissimilar1 that in the one1 it is to   
the electric chain like platinum1 and in
 the other it is like zinc2 so that     
powerful galvanic machines have been    
constructed of this one metal4  ,among  
the elements are several instances of   
remarkable similarity of properties4    
,thus there is a strong resemblance     
between platinum and iridium2 bromine   
and iodine2 iron1 manganese1 and        
magnesium2 cobalt and nickel2 phosphorus
 and arsenic2 but this resemblance      
consists mainly in their forming        
isomorphous compounds in which these    
elements exist in the same relative     
proportion4 ,these compounds are        
similar1 because the atoms of which they
 are composed are arranged in the same  
manner4 ,the converse of this is also   
true3 nitrate of strontia becomes quite 
dissimilar to its common state if a     
certain proportion of water is taken    
into its composition4  ,if we suppose   
selenium to be merely modified sulphur1 
and phosphorus modified arsenic1 how    

does it happen1 we must inquire1 that   
sulphuric acid and selenic acid1        
phosphoric and arsenic acid1            
respectively form compounds which it is 
impossible to distinguish by their form 
and solubility8 ,were these merely      
isomeric1 they ought to exhibit         
properties quite dissimilar6  ,we have  
not1 ,i believe1 at present the remotest
 ground to suppose that any one of those
 substances which chemists regard as    
elements can be converted into another4 
,such a conversion1 indeed1 would       
presuppose that the element was composed
 of two or more ingredients1 and was in 
fact not an element2 and until the      
decomposition of these bodies is        
accomplished1 and their constituents    
discovered1 all pretensions to such     
conversions deserve no notice4  ,dr4    
,brown of ,edinburgh thought he had     
converted iron into rhodium1 and carbon 
or paracyanogen into silicon4 ,his paper
 upon this subject was published in the 
,transactions of the ,royal ,society of 

,edinburgh1 and contained internal      
evidence1 without a repetition of his   
experiments1 that he was totally        
unacquainted with the principles of     
chemical analysis4 ,but his experiments 
have been carefully repeated by         
qualified persons1 and they have        
completely proved his ignorance3 his    
rhodium is iron1 and his silicon an     
impure incombustible coal4     ,,letter 
,,vi   ,my dear ,sir1  ,one of the most 
remarkable effects of the recent        
progress of science is the alliance of  
chemistry with physiology1 by which a   
new and unexpected light has been thrown
 upon the vital processes of plants and 
animals4 ,we have now no longer any     
difficulty in understanding the         
different actions of aliments1 poisons1 
and remedial agents--we have a clear    
conception of the causes of hunger1 of  
the exact nature of death2 and we are   
not1 as formerly1 obliged to content    
ourselves with a mere description of    
their symptoms4 ,it is now ascertained  

with positive certainty1 that all the   
substances which constitute the food of 
man must be divided into two great      
classes1 one of which serves for the    
nutrition and reproduction of the animal
 body1 whilst the other ministers to    
quite different purposes4 ,thus starch1 
gum1 sugar1 beer1 wine1 spirits1 c41    
furnish no element capable of entering  
into the composition of blood1 muscular 
fibre1 or any part which is the seat of 
the vital principle4 ,it must surely be 
universally interesting to trace the    
great change our views have undergone   
upon these subjects1 as well as to      
become acquainted with the researches   
from which our present knowledge is     
derived4  ,the primary conditions of the
 maintenance of animal life1 are a      
constant supply of certain matters1     
animal food1 and of oxygen1 in the shape
 of atmospheric air4 ,during every      
moment of life1 oxygen is absorbed from 
the atmosphere in the organs of         
respiration1 and the act of breathing   

cannot cease while life continues4  ,the
 observations of physiologists have     
demonstrated that the body of an adult  
man supplied abundantly with food1      
neither increases nor diminishes in     
weight during twenty-four hours1 and yet
 the quantity of oxygen absorbed into   
his system1 in that period1 is very     
considerable4 ,according to the         
experiments of ,lavoisier1 an adult man 
takes into his system from the          
atmosphere1 in one year1 no less than   
#gdf pounds weight of oxygen2 the       
calculations of ,menzies make the       
quantity amount even to #hcg pounds2 but
 we find his weight at the end of the   
year either exactly the same or         
different one way or the other by at    
most a few pounds4 ,what1 it may be     
asked1 has become of the enormous amount
 of oxygen thus introduced into the     
human system in the course of one year8 
,we can answer this question            
satisfactorily4 ,no part of the oxygen  
remains in the body1 but is given out   

again1 combined with carbon and         
hydrogen4 ,the carbon and hydrogen of   
certain parts of the animal body combine
 with the oxygen introduced through the 
lungs and skin1 and pass off in the     
forms of carbonic acid and vapour of    
water4 ,at every expiration and every   
moment of life1 a certain amount of its 
elements are separated from the animal  
organism1 having entered into           
combination with the oxygen of the      
atmosphere4  ,in order to obtain a basis
 for the approximate calculation1 we may
 assume1 with ,lavoisier and ,seguin1   
that an adult man absorbs into his      
system #cb #a_/b ounces of oxygen       
daily1--that is1 #df1jcg cubic inches   
#ae1ffa grains1 ,french weight2 and     
further1 that the weight of the whole   
mass of his blood is #bd pounds1 of     
which #hj per cent4 is water4 ,now1 from
 the known composition of the blood1 we 
know that in order to convert its whole 
amount of carbon and hydrogen into      
carbonic acid and water1 #fd4ajb grains 

of oxygen are required4 ,this quantity  
will be taken into the system in four   
days and five hours4 ,whether the oxygen
 enters into combination directly with  
the elements of the blood1 or with the  
carbon and hydrogen of other parts of   
the body1 it follows inevitably--the    
weight of the body remaining unchanged  
and in a normal condition--that as much 
of these elements as will suffice to    
supply #bd pounds of blood1 must be     
taken into the system in four days and  
five hours2 and this necessary amount is
 furnished by the food4  ,we have not1  
however1 remained satisfied with mere   
approximation3 we have determined       
accurately1 in certain cases1 the       
quantity of carbon taken daily in the   
food1 and of that which passes out of   
the body in the faeces and urine        
combined--that is1 uncombined with      
oxygen2 and from these investigations it
 appears that an adult man taking       
moderate exercise consumes #ac4i ounces 
of carbon1 which pass off through the   

skin and lungs as carbonic acid gas4 #a 
,it requires #cg ounces of oxygen to    
convert #ac #i_/aj of carbon into       
carbonic acid4 ,again2 according to the 
analysis of ,boussingault1 7,annales de 
,chim4 et de ,phys41 lxx4 i4 p4#acf71 a 
horse consumes #gi #a_/aj ounces of     
carbon in twenty-four hours1 a milch cow
 #gj #c_/d ounces2 so that the horse    
requires #ac pounds #c #a_/b ounces1 and
 the cow #aa pounds #aj #c_/d ounces of 
oxygen4 #b  ,as no part of the oxygen   
taken into the system of an animal is   
given off in any other form than        
combined with carbon or hydrogen1 and as
 in a normal condition1 or state of     
health1 the carbon and hydrogen so given
 off are replaced by those elements in  
the food1 it is evident that the amount 
of nourishment required by an animal for
 its support must be in a direct ratio  
with the quantity of oxygen taken in to 
its system4 ,two animals which in equal 
times take up by means of the lungs and 
skin unequal quantities of oxygen1      

consume an amount of food unequal in the
 same ratio4 ,the consumption of oxygen 
in a given time may be expressed by the 
number of respirations2 it is1          
therefore1 obvious that in the same     
animal the quantity of nourishment      
required must vary with the force and   
number of respirations4 ,a child        
breathes quicker than an adult1 and1    
consequently1 requires food more        
frequently and proportionably in larger 
quantity1 and bears hunger less easily4 
,a bird deprived of food dies on the    
third day1 while a serpent1 confined    
under a bell1 respires so slowly that   
the quantity of carbonic acid generated 
in an hour can scarcely be observed1 and
 it will live three months1 or longer1  
without food4 ,the number of            
respirations is fewer in a state of rest
 than during labour or exercise3 the    
quantity of food necessary in both cases
 must be in the same ratio4 ,an excess  
of food1 a want of a due amount of      
respired oxygen1 or of exercise1 as also

 great exercise 7which obliges us to    
take an increased supply of food71      
together with weak organs of digestion1 
are incompatible with health4  ,but the 
quantity of oxygen received by an animal
 through the lungs not only depends upon
 the number of respirations1 but also   
upon the temperature of the respired    
air4 ,the size of the thorax of an      
animal is unchangeable2 we may therefore
 regard the volume of air which enters  
at every inspiration as uniform4 ,but   
its weight1 and consequently the amount 
of oxygen it contains1 is not constant4 
,air is expanded by heat1 and contracted
 by cold--an equal volume of hot and    
cold air contains1 therefore1 an unequal
 amount of oxygen4 ,in summer           
atmospheric air contains water in the   
form of vapour1 it is nearly deprived of
 it in winter2 the volume of oxygen in  
the same volume of air is smaller in    
summer than in winter4 ,in summer and   
winter1 at the pole and at the equator1 
we inspire an equal volume of air2 the  

cold air is warmed during respiration   
and acquires the temperature of the     
body4 ,in order1 therefore1 to introduce
 into the lungs a given amount of       
oxygen1 less expenditure of force is    
necessary in winter than in summer1 and 
for the same expenditure of force more  
oxygen is inspired in winter4 ,it is    
also obvious that in an equal number of 
respirations we consume more oxygen at  
the level of the sea than on a mountain4
  ,the oxygen taken into the system is  
given out again in the same form1 both  
in summer and winter3 we expire more    
carbon at a low than at a high          
temperature1 and require more or less   
carbon in our food in the same          
proportion2 and1 consequently1 more is  
respired in ,sweden than in ,sicily1 and
 in our own country and eighth more in  
winter than in summer4 ,even if an equal
 weight of food is consumed in hot and  
cold climates1 ,infinite ,wisdom has    
ordained that very unequal proportions  
of carbon shall be taken in it4 ,the    

food prepared for the inhabitants of    
southern climes does not contain in a   
fresh state more than #ab per cent4 of  
carbon1 while the blubber and train oil 
which feed the inhabitants of ,polar    
regions contain #ff to #hj per cent4 of 
that element4  ,from the same cause it  
is comparatively easy to be temperate in
 warm climates1 or to bear hunger for a 
long time under the equator2 but cold   
and hunger united very soon produce     
exhaustion4  ,the oxygen of the         
atmosphere received into the blood in   
the lungs1 and circulated throughout    
every part of the animal body1 acting   
upon the elements of the food1 is the   
source of animal heat4  ,footnote #a3   
,this account is deduced from           
observations made upon the average daily
 consumption of about #cj soldiers in   
barracks4 ,the food of these men1       
consisting of meat1 bread1 potatoes1    
lentils1 peas1 beans1 butter1 salt1     
pepper1 c41 was accurately weighed      
during a month1 and each article        

subjected to ultimate analysis4 ,of the 
quantity of food1 beer1 and spirits1    
taken by the men when out of barracks1  
we have a close approximation from the  
report of the sergeant2 and from the    
weight and analysis of the faeces and   
urine1 it appears that the carbon which 
passes off through these channels may be
 considered equivalent to the amount    
taken in that portion of the food1 and  
of sour-crout1 which was not included in
 the estimate4  ,footnote #b3 #ag4e     
ounces  #j4e kilogramme4     ,,letter   
,,vii   ,my dear ,sir1  ,the source of  
animal heat1 its laws1 and the influence
 it exerts upon the functions of the    
animal body1 constitute a curious and   
highly interesting subject1 to which ,i 
would now direct your attention4  ,all  
living creatures1 whose existence       
depends upon the absorption of oxygen1  
possess within themselves a source of   
heat1 independent of surrounding        
objects4  ,this general truth applies to
 all animals1 and extends to the seed of

 plants in the act of germination1 to   
flower-buds when developing1 and fruits 
during their maturation4  ,in the animal
 body1 heat is produced only in those   
parts to which arterial blood1 and with 
it the oxygen absorbed in respiration1  
is conveyed4 ,hair1 wool1 and feathers1 
receive no arterial blood1 and1         
therefore1 in them no heat is developed4
 ,the combination of a combustible      
substance with oxygen is1 under all     
circumstances1 the only source of animal
 heat4 ,in whatever way carbon may      
combine with oxygen1 the act of         
combination is accompanied by the       
disengagement of heat4 ,it is           
indifferent whether this combination    
takes place rapidly or slowly1 at a high
 or at a low temperature3 the amount of 
heat liberated is a constant quantity4  
,the carbon of the food1 being converted
 into carbonic acid within the body1    
must give out exactly as much heat as if
 it had been directly burnt in oxygen   
gas or in common air2 the only          

difference is1 the production of the    
heat is diffused over unequal times4 ,in
 oxygen gas the combustion of carbon is 
rapid and the heat intense2 in          
atmospheric air it burns slower and for 
a longer time1 the temperature being    
lower2 in the animal body the           
combination is still more gradual1 and  
the heat is lower in proportion4  ,it is
 obvious that the amount of heat        
liberated must increase or diminish with
 the quantity of oxygen introduced in   
equal times by respiration4 ,those      
animals1 therefore1 which respire       
frequently1 and consequently consume    
much oxygen1 possess a higher           
temperature than others1 which1 with a  
body of equal size to be heated1 take   
into the system less oxygen4 ,the       
temperature of a child 7#ajb deg7 is    
higher than that of an adult 7#ii #a_/b 
deg74 ,that of birds 7#ajd deg to #aje4d
 deg7 is higher than that of quadrupeds 
7#ih #a_/b deg to #ajj4d deg7 or than   
that of fishes or amphibia1 whose proper

 temperature is from #b4g to #c4f deg   
higher than that of the medium in which 
they live4 ,all animals1 strictly       
speaking1 are warm-blooded2 but in those
 only which possess lungs is the        
temperature of the body quite           
independent of the surrounding medium4  
,the most trustworthy observations prove
 that in all climates1 in the temperate 
zones as well as at the equator or the  
poles1 the temperature of the body in   
man1 and in what are commonly called    
warm-blooded animals1 is invariably the 
same2 yet how different are the         
circumstances under which they live6    
,the animal body is a heated mass1 which
 bears the same relation to surrounding 
objects as any other heated mass4 ,it   
receives heat when the surrounding      
objects are hotter1 it loses heat when  
they are colder1 than itself4  ,we know 
that the rapidity of cooling increases  
with the difference between the         
temperature of the heated body and that 
of the surrounding medium2 that is1 the 

colder the surrounding medium the       
shorter the time required for the       
cooling of the heated body4  ,how       
unequal1 then1 must be the loss of heat 
in a man at ,palermo1 where the external
 temperature is nearly equal to that of 
the body1 and in the polar regions1     
where the external temperature is from  
#gj deg to #ij deg lower6  ,yet1        
notwithstanding this extremely unequal  
loss of heat1 experience has shown that 
the blood of the inhabitant of the      
arctic circle has a temperature as high 
as that of the native of the south1 who 
lives in so different a medium4  ,this  
fact1 when its true significance is     
perceived1 proves that the heat given   
off to the surrounding medium is        
restored within the body with great     
rapidity4 ,this compensation must       
consequently take place more rapidly in 
winter than in summer1 at the pole than 
at the equator4  ,now1 in different     
climates the quantity of oxygen         
introduced into the system by           

respiration1 as has been already shown1 
varies according to the temperature of  
the external air2 the quantity of       
inspired oxygen increases with the loss 
of heat by external cooling1 and the    
quantity of carbon or hydrogen necessary
 to combine with this oxygen must be    
increased in the same ratio4  ,it is    
evident that the supply of the heat lost
 by cooling is effected by the mutual   
action of the elements of the food and  
the inspired oxygen1 which combine      
together4 ,to make use of a familiar1   
but not on that account a less just     
illustration1 the animal body acts1 in  
this respect1 as a furnace1 which we    
supply with fuel4 ,it signifies nothing 
what intermediate forms food may assume1
 what changes it may undergo in the     
body2 the last change is uniformly the  
conversion of its carbon into carbonic  
acid1 and of its hydrogen into water4   
,the unassimilated nitrogen of the food1
 along with the unburned or unoxidised  
carbon1 is expelled in the urine or in  

the solid excrements4 ,in order to keep 
up in the furnace a constant            
temperature1 we must vary the supply of 
fuel according to the external          
temperature1 that is1 according to the  
supply of oxygen4  ,in the animal body  
the food is the fuel2 with a proper     
supply of oxygen we obtain the heat     
given out during its oxidation or       
combustion4 ,in winter1 when we take    
exercise in a cold atmosphere1 and when 
consequently the amount of inspired     
oxygen increases1 the necessity for food
 containing carbon and hydrogen         
increases in the same ratio2 and by     
gratifying the appetite thus excited1 we
 obtain the most efficient protection   
against the most piercing cold4 ,a      
starving man is soon frozen to death4   
,the animals of prey in the arctic      
regions1 as every one knows1 far exceed 
in voracity those of the torrid zone4   
,in cold and temperate climates1 the    
air1 which incessantly strives to       
consume the body1 urges man to laborious

 efforts in order to furnish the means  
of resistance to its action1 while1 in  
hot climates1 the necessity of labour to
 provide food is far less urgent4  ,our 
clothing is merely an equivalent for a  
certain amount of food4 ,the more warmly
 we are clothed the less urgent becomes 
the appetite for food1 because the loss 
of heat by cooling1 and consequently the
 amount of heat to be supplied by the   
food1 is diminished4  ,if we were to go 
naked1 like certain savage tribes1 or if
 in hunting or fishing we were exposed  
to the same degree of cold as the       
,samoyedes1 we should be able with ease 
to consume #aj lbs4 of flesh1 and       
perhaps a dozen of tallow candles into  
the bargain1 daily1 as warmly clad      
travellers have related with            
astonishment of these people4 ,we should
 then also be able to take the same     
quantity of brandy or train oil without 
bad effects1 because the carbon and     
hydrogen of these substances would only 
suffice to keep up the equilibrium      

between the external temperature and    
that of our bodies4  ,according to the  
preceding expositions1 the quantity of  
food is regulated by the number of      
respirations1 by the temperature of the 
air1 and by the amount of heat given off
 to the surrounding medium4  ,no        
isolated fact1 apparently opposed to    
this statement1 can affect the truth of 
this natural law4 ,without temporary or 
permanent injury to health1 the         
,neapolitan cannot take more carbon and 
hydrogen in the shape of food than he   
expires as carbonic acid and water2 and 
the ,esquimaux cannot expire more carbon
 and hydrogen than he takes in the      
system as food1 unless in a state of    
disease or of starvation4 ,let us       
examine these states a little more      
closely4  ,the ,englishman in ,jamaica  
perceives with regret the disappearance 
of his appetite1 previously a source of 
frequently recurring enjoyment2 and he  
succeeds1 by the use of cayenne pepper1 
and the most powerful stimulants1 in    

enabling himself to take as much food as
 he was accustomed to eat at home4 ,but 
the whole of the carbon thus introduced 
into the system is not consumed2 the    
temperature of the air is too high1 and 
the oppressive heat does not allow him  
to increase the number of respirations  
by active exercise1 and thus to         
proportion the waste to the amount of   
food taken2 disease of some kind1       
therefore1 ensues4  ,on the other hand1 
,england sends her sick to southern     
regions1 where the amount of the oxygen 
inspired is diminished in a very large  
proportion4 ,those whose diseased       
digestive organs have in a greater or   
less degree lost the power of bringing  
the food into the state best adapted for
 oxidation1 and therefore are less able 
to resist the oxidising influence of the
 atmosphere of their native climate1    
obtain a great improvement in health4   
,the diseased organs of digestion have  
power to place the diminished amount of 
food in equilibrium with the inspired   

oxygen1 in the mild climate2 whilst in a
 colder region the organs of respiration
 themselves would have been consumed in 
furnishing the necessary resistance to  
the action of the atmospheric oxygen4   
,in our climate1 hepatic diseases1 or   
those arising from excess of carbon1    
prevail in summer2 in winter1 pulmonary 
diseases1 or those arising from excess  
of oxygen1 are more frequent4  ,the     
cooling of the body1 by whatever cause  
it may be produced1 increases the amount
 of food necessary4 ,the mere exposure  
to the open air1 in a carriage or on the
 deck of a ship1 by increasing radiation
 and vaporisation1 increases the loss of
 heat1 and compels us to eat more than  
usual4 ,the same is true of those who   
are accustomed to drink large quantities
 of cold water1 which is given off at   
the temperature of the body1 #ih #a_/b  
deg4 ,it increases the appetite1 and    
persons of weak constitution find it    
necessary1 by continued exercise1 to    
supply to the system the oxygen required

 to restore the heat abstracted by the  
cold water4 ,loud and long continued    
speaking1 the crying of infants1 moist  
air1 all exert a decided and appreciable
 influence on the amount of food which  
is taken4  ,we have assumed that carbon 
and hydrogen especially1 by combining   
with oxygen1 serve to produce animal    
heat4 ,in fact1 observation proves that 
the hydrogen of the food plays a no less
 important part than the carbon4  ,the  
whole process of respiration appears    
most clearly developed1 when we consider
 the state of a man1 or other animal1   
totally deprived of food4  ,the first   
effect of starvation is the             
disappearance of fat1 and this fat      
cannot be traced either in the urine or 
in the scanty faeces4 ,its carbon and   
hydrogen have been given off through the
 skin and lungs in the form of oxidised 
products2 it is obvious that they have  
served to support respiration4  ,in the 
case of a starving man1 #cb #a_/b oz4 of
 oxygen enter the system daily1 and are 

given out again in combination with a   
part of his body4 ,currie mentions the  
case of an individual who was unable to 
swallow1 and whose body lost #ajj lbs4  
in weight during a month2 and1 according
 to ,martell 7,trans4 ,linn4 ,soc41 vol4
 xi4 p4#daa71 a fat pig1 overwhelmed in 
a slip of earth1 lived #afj days without
 food1 and was found to have diminished 
in weight1 in that time1 more than #abj 
lbs4 ,the whole history of hybernating  
animals1 and the well-established facts 
of the periodical accumulation1 in      
various animals1 of fat1 which1 at other
 periods1 entirely disappears1 prove    
that the oxygen1 in the respiratory     
process1 consumes1 without exception1   
all such substances as are capable of   
entering into combination with it4 ,it  
combines with whatever is presented to  
it2 and the deficiency of hydrogen is   
the only reason why carbonic acid is the
 chief product2 for1 at the temperature 
of the body1 the affinity of hydrogen   
for oxygen far surpasses that of carbon 

for the same element4  ,we know1 in     
fact1 that the graminivora expire a     
volume of carbonic acid equal to that of
 the oxygen inspired1 while the         
carnivora1 the only class of animals    
whose food contains fat1 inspire more   
oxygen than is equal in volume to the   
carbonic acid expired4 ,exact           
experiments have shown1 that in many    
cases only half the volume of oxygen is 
expired in the form of carbonic acid4   
,these observations cannot be gainsaid1 
and are far more convincing than those  
arbitrary and artificially produced     
phenomena1 sometimes called experiments2
 experiments which1 made as too often   
they are1 without regard to the         
necessary and natural conditions1       
possess no value1 and may be entirely   
dispensed with2 especially when1 as in  
the present case1 ,nature affords the   
opportunity for observation1 and when we
 make a rational use of that            
opportunity4  ,in the progress of       
starvation1 however1 it is not only the 

fat which disappears1 but also1 by      
degrees all such of the solids as are   
capable of being dissolved4 ,in the     
wasted bodies of those who have suffered
 starvation1 the muscles are shrunk and 
unnaturally soft1 and have lost their   
contractibility2 all those parts of the 
body which were capable of entering into
 the state of motion have served to     
protect the remainder of the frame from 
the destructive influence of the        
atmosphere4 ,towards the end1 the       
particles of the brain begin to undergo 
the process of oxidation1 and delirium1 
mania1 and death close the scene2 that  
is to say1 all resistance to the        
oxidising power of the atmospheric      
oxygen ceases1 and the chemical process 
of eremacausis1 or decay1 commences1 in 
which every part of the body1 the bones 
excepted1 enters into combination with  
oxygen4  ,the time which is required to 
cause death by starvation depends on the
 amount of fat in the body1 on the      
degree of exercise1 as in labour or     

exertion of any kind1 on the temperature
 of the air1 and finally1 on the        
presence or absence of water4 ,through  
the skin and lungs there escapes a      
certain quantity of water1 and as the   
presence of water is essential to the   
continuance of the vital motions1 its   
dissipation hastens death4 ,cases have  
occurred1 in which a full supply of     
water being accessible to the sufferer1 
death has not occurred till after the   
lapse of twenty days4 ,in one case1 life
 was sustained in this way for the      
period of sixty days4  ,in all chronic  
diseases death is produced by the same  
cause1 namely1 the chemical action of   
the atmosphere4 ,when those substances  
are wanting1 whose function in the      
organism is to support the process of   
respiration1 when the diseased organs   
are incapable of performing their proper
 function of producing these substances1
 when they have lost the power of       
transforming the food into that shape in
 which it may1 by entering into         

combination with the oxygen of the air1 
protect the system from its influence1  
then1 the substance of the organs       
themselves1 the fat of the body1 the    
substance of the muscles1 the nerves1   
and the brain1 are unavoidably consumed4
  ,the true cause of death in these     
cases is the respiratory process1 that  
is1 the action of the atmosphere4  ,a   
deficiency of food1 and a want of power 
to convert the food into a part of the  
organism1 are both1 equally1 a want of  
resistance2 and this is the negative    
cause of the cessation of the vital     
process4 ,the flame is extinguished1    
because the oil is consumed2 and it is  
the oxygen of the air which has consumed
 it4  ,in many diseases substances are  
produced which are incapable of         
assimilation4 ,by the mere deprivation  
of food1 these substances are removed   
from the body without leaving a trace   
behind2 their elements have entered into
 combination with the oxygen of the air4
  ,from the first moment that the       

function of the lungs or of the skin is 
interrupted or disturbed1 compounds1    
rich in carbon1 appear in the urine1    
which acquires a brown colour4 ,over the
 whole surface of the body oxygen is    
absorbed1 and combines with all the     
substances which offer no resistance to 
it4 ,in those parts of the body where   
the access of oxygen is impeded2 for    
example1 in the arm-pits1 or in the     
soles of the feet1 peculiar compounds   
are given out1 recognisable by their    
appearance1 or by their odour4 ,these   
compounds contain much carbon4          
,respiration is the falling weight--the 
bent spring1 which keeps the clock in   
motion2 the inspirations and expirations
 are the strokes of the pendulum which  
regulate it4 ,in our ordinary           
time-pieces1 we know with mathematical  
accuracy the effect produced on their   
rate of going1 by changes in the length 
of the pendulum1 or in the external     
temperature4 ,few1 however1 have a clear
 conception of the influence of air and 

temperature on the health of the human  
body2 and yet the research into the     
conditions necessary to keep it in the  
normal state is not more difficult than 
in the case of a clock4     ,,letter    
,,viii   ,my dear ,sir1  ,having        
attempted in my last letter to explain  
to you the simple and admirable office  
subserved by the oxygen of the          
atmosphere in its combination with      
carbon in the animal body1 ,i will now  
proceed to present you with some remarks
 upon those materials which sustain its 
mechanisms in motion1 and keep up their 
various functions1--namely1 the         
,aliments4  ,if the increase in mass in 
an animal body1 the development and     
reproduction of its organs depend upon  
the blood1 then those substances only   
which are capable of being converted    
into blood can be properly regarded as  
nourishment4 ,in order then to ascertain
 what parts of our food are nutritious1 
we must compare the composition of the  
blood with the composition of the       

various articles taken as food4  ,two   
substances require especial             
consideration as the chief ingredients  
of the blood2 one of these separates    
immediately from the blood when it is   
withdrawn from the circulation4  ,it is 
well known that in this case blood      
coagulates1 and separates into a        
yellowish liquid1 the serum of the      
blood1 and a gelatinous mass1 which     
adheres to a rod or stick in soft1      
elastic fibres1 when coagulating blood  
is briskly stirred4 ,this is the fibrine
 of the blood1 which is identical in all
 its properties with muscular fibre1    
when the latter is purified from all    
foreign matters4  ,the second principal 
ingredient of the blood is contained in 
the serum1 and gives to this liquid all 
the properties of the white of eggs1    
with which it is indeed identical4 ,when
 heated1 it coagulates into a white     
elastic mass1 and the coagulating       
substance is called albumen4  ,fibrine  
and albumen1 the chief ingredients of   

blood1 contain1 in all1 seven chemical  
elements1 among which nitrogen1         
phosphorus1 and sulphur are found4 ,they
 contain also the earth of bones4 ,the  
serum retains in solution sea salt and  
other salts of potash and soda1 in which
 the acids are carbonic1 phosphoric1 and
 sulphuric acids4 ,the globules of the  
blood contain fibrine and albumen1 along
 with a red colouring matter1 in which  
iron is a constant element4 ,besides    
these1 the blood contains certain fatty 
bodies in small quantity1 which differ  
from ordinary fats in several of their  
properties4  ,chemical analysis has led 
to the remarkable result1 that fibrine  
and albumen contain the same organic    
elements united in the same             
proportion1--i4e41 that they are        
isomeric1 their chemical                
composition--the proportion of their    
ultimate elements--being identical4 ,but
 the difference of their external       
properties shows that the particles of  
which they are composed are arranged in 

a different order4 7,see ,letter ,v74   
,this conclusion has lately been        
beautifully confirmed by a distinguished
 physiologist 7,denis71 who has         
succeeded in converting fibrine into    
albumen1 that is1 in giving it the      
solubility1 and coagulability by heat1  
which characterise the white of egg4    
,fibrine and albumen1 besides having the
 same composition1 agree also in this1  
that both dissolve in concentrated      
muriatic acid1 yielding a solution of an
 intense purple colour4 ,this solution1 
whether made with fibrine or albumen1   
has the very same re-actions with all   
substances yet tried4  ,both albumen and
 fibrine1 in the process of nutrition1  
are capable of being converted into     
muscular fibre1 and muscular fibre is   
capable of being reconverted into blood4
 ,these facts have long been established
 by physiologists1 and chemistry has    
merely proved that these metamorphoses  
can be accomplished under the influence 
of a certain force1 without the aid of a

 third substance1 or of its elements1   
and without the addition of any foreign 
element1 or the separation of any       
element previously present in these     
substances4  ,if we now compare the     
composition of all organised parts with 
that of fibrine and albumen1 the        
following relations present             
themselves3--  ,all parts of the animal 
body which have a decided shape1 which  
form parts of organs1 contain nitrogen4 
,no part of an organ which possesses    
motion and life is destitute of         
nitrogen2 all of them contain likewise  
carbon and the elements of water2 the   
latter1 however1 in no case in the      
proportion to form water4  ,the chief   
ingredients of the blood contain nearly 
#ag per cent4 of nitrogen1 and from     
numerous analyses it appears that no    
part of an organ contains less than #ag 
per cent4 of nitrogen4  ,the most       
convincing experiments and observations 
have proved that the animal body is     
absolutely incapable of producing an    

elementary body1 such as carbon or      
nitrogen1 out of substances which do not
 contain it2 and it obviously follows1  
that all kinds of food fit for the      
production either of blood1 or of       
cellular tissue1 membranes1 skin1 hair1 
muscular fibre1 c41 must contain a      
certain amount of nitrogen1 because that
 element is essential to the composition
 of the above-named organs2 because the 
organs cannot create it from the other  
elements presented to them2 and1        
finally1 because no nitrogen is absorbed
 from the atmosphere in the vital       
process4  ,the substance of the brain   
and nerves contains a large quantity of 
albumen1 and1 in addition to this1 two  
peculiar fatty acids1 distinguished from
 other fats by containing phosphorus    
7phosphoric acid874 ,one of these       
contains nitrogen 7,fremy74  ,finally1  
water and common fat are those          
ingredients of the body which are       
destitute of nitrogen4 ,both are        
amorphous or unorganised1 and only so   

far take part in the vital process as   
that their presence is required for the 
due performance of the vital functions4 
,the inorganic constituents of the body 
are1 iron1 lime1 magnesia1 common salt1 
and the alkalies4  ,the nutritive       
process is seen in its simplest form in 
carnivorous animals4 ,this class of     
animals lives on the blood and flesh of 
the graminivora2 but this blood and     
flesh are1 in all their properties1     
identical with their own4 ,neither      
chemical nor physiological differences  
can be discovered4  ,the nutriment of   
carnivorous animals is derived          
originally from blood2 in their stomach 
it becomes dissolved1 and capable of    
reaching all other parts of the body2 in
 its passage it is again converted into 
blood1 and from this blood are          
reproduced all those parts of their     
organisation which have undergone change
 or metamorphosis4  ,with the exception 
of hoofs1 hair1 feathers1 and the earth 
of bones1 every part of the food of     

carnivorous animals is capable of       
assimilation4  ,in a chemical sense1    
therefore1 it may be said that a        
carnivorous animal1 in supporting the   
vital process1 consumes itself4 ,that   
which serves for its nutrition is       
identical with those parts of its       
organisation which are to be renewed4   
,the process of nutrition in            
graminivorous animals appears at first  
sight altogether different4 ,their      
digestive organs are less simple1 and   
their food consists of vegetables1 the  
great mass of which contains but little 
nitrogen4  ,from what substances1 it may
 be asked1 is the blood formed1 by means
 of which of their organs are developed8
 ,this question may be answered with    
certainty4  ,chemical researches have   
shown1 that all such parts of vegetables
 as can afford nutriment to animals     
contain certain constituents which are  
rich in nitrogen2 and the most ordinary 
experience proves that animals require  
for their support and nutrition less of 

these parts of plants in proportion as  
they abound in the nitrogenised         
constituents4 ,animals cannot be fed on 
matters destitute of these nitrogenised 
constituents4  ,these important products
 of vegetation are especially abundant  
in the seeds of the different kinds of  
grain1 and of peas1 beans1 and lentils2 
in the roots and the juices of what are 
commonly called vegetables4 ,they exist1
 however1 in all plants1 without        
exception1 and in every part of plants  
in larger or smaller quantity4  ,these  
nitrogenised forms of nutriment in the  
vegetable kingdom may be reduced to     
three substances1 which are easily      
distinguished by their external         
characters4 ,two of them are soluble in 
water1 the third is insoluble4  ,when   
the newly-expressed juices of vegetables
 are allowed to stand1 a separation     
takes place in a few minutes4 ,a        
gelatinous precipitate1 commonly of a   
green tinge1 is deposited1 and this1    
when acted on by liquids which remove   

the colouring matter1 leaves a grayish  
white substance1 well known to druggists
 as the deposite from vegetable juices4 
,this is one of the nitrogenised        
compounds which serves for the nutrition
 of animals1 and has been named         
vegetable fibrine4 ,the juice of grapes 
is especially rich in this constituent1 
but it is most abundant in the seeds of 
wheat1 and of the cerealia generally4   
,it may be obtained from wheat flour by 
a mechanical operation1 and in a state  
of tolerable purity2 it is then called  
gluten1 but the glutinous property      
belongs1 not to vegetable fibrine1 but  
to a foreign substance1 present in small
 quantity1 which is not found in the    
other cerealia4  ,the method by which it
 is obtained sufficiently proves that it
 is insoluble in water2 although we     
cannot doubt that it was originally     
dissolved in the vegetable juice1 from  
which it afterwards separated1 exactly  
as fibrine does from blood4  ,the second
 nitrogenised compound remains dissolved

 in the juice after the separation of   
the fibrine4 ,it does not separate from 
the juice at the ordinary temperature1  
but is instantly coagulated when the    
liquid containing it is heated to the   
boiling point4  ,when the clarified     
juice of nutritious vegetables1 such as 
cauliflower1 asparagus1 mangelwurzel1 or
 turnips1 is made to boil1 a coagulum is
 formed1 which it is absolutely         
impossible to distinguish from the      
substance which separates as a coagulum1
 when the serum of blood1 or the white  
of an egg1 diluted with water1 are      
heated to the boiling point4 ,this is   
vegetable albumen4 ,it is found in the  
greatest abundance in certain seeds1 in 
nuts1 almonds1 and others1 in which the 
starch of the gramineae is replaced by  
oil4  ,the third nitrogenised           
constituent of the vegetable food of    
animals is vegetable caseine4 ,it is    
chiefly found in the seeds of peas1     
beans1 lentils1 and similar leguminous  
seeds4 ,like vegetable albumen1 it is   

soluble in water1 but differs from it in
 this1 that its solution is not         
coagulated by heat4 ,when the solution  
is heated or evaporated1 a skin forms on
 its surface1 and the addition of an    
acid causes a coagulum1 just as in      
animal milk4  ,these three nitrogenised 
compounds1 vegetable fibrine1 albumen1  
and caseine1 are the true nitrogenised  
constituents of the food of             
graminivorous animals2 all other        
nitrogenised compounds occurring in     
plants1 are either rejected by animals1 
as in the case of the characteristic    
principles of poisonous and medicinal   
plants1 or else they occur in the food  
in such very small proportion1 that they
 cannot possibly contribute to the      
increase of mass in the animal body4    
,the chemical analysis of these three   
substances has led to the very          
interesting result that they contain the
 same organic elements1 united in the   
same proportion by weight2 and1 what is 
still more remarkable1 that they are    

identical in composition with the chief 
constituents of blood1 animal fibrine1  
and albumen4 ,they all three dissolve in
 concentrated muriatic acid with the    
same deep purple colour1 and even in    
their physical characters1 animal       
fibrine and albumen are in no respect   
different from vegetable fibrine and    
albumen4 ,it is especially to be        
noticed1 that by the phrase1 identity of
 composition1 we do not here intend mere
 similarity1 but that even in regard to 
the presence and relative amount of     
sulphur1 phosphorus1 and phosphate of   
lime1 no difference can be observed4    
,how beautifully and admirably simple1  
with the aid of these discoveries1      
appears the process of nutrition in     
animals1 the formation of their organs1 
in which vitality chiefly resides6      
,those vegetable principles1 which in   
animals are used to form blood1 contain 
the chief constituents of blood1 fibrine
 and albumen1 ready formed1 as far as   
regards their composition4 ,all plants1 

besides1 contain a certain quantity of  
iron1 which reappears in the colouring  
matter of the blood4 ,vegetable fibrine 
and animal fibrine1 vegetable albumen   
and animal albumen1 hardly differ1 even 
in form2 if these principles be wanting 
in the food1 the nutrition of the animal
 is arrested2 and when they are present1
 the graminivorous animal obtains in its
 food the very same principles on the   
presence of which the nutrition of the  
carnivora entirely depends4  ,vegetables
 produce in their organism the blood of 
all animals1 for the carnivora1 in      
consuming the blood and flesh of the    
graminivora1 consume1 strictly speaking1
 only the vegetable principles which    
have served for the nutrition of the    
latter4 ,vegetable fibrine and albumen  
take the form in the stomach of the     
graminivorous animal as animal fibrine  
and albumen do in that of the           
carnivorous animal4  ,from what has been
 said1 it follows that the development  
of the animal organism and its growth   

are dependent on the reception of       
certain principles identical with the   
chief constituents of blood4  ,in this  
sense we may say that the animal        
organism gives to the blood only its    
form2 that it is incapable of creating  
blood out of other substances which do  
not already contain the chief           
constituents of that fluid4 ,we cannot1 
indeed1 maintain that the animal        
organism has no power to form other     
compounds1 for we know that it is       
capable of producing an extensive series
 of compounds1 differing in composition 
from the chief constituents of blood2   
but these last1 which form the          
starting-point of the series1 it cannot 
produce4  ,the animal organism is a     
higher kind of vegetable1 the           
development of which begins with those  
substances with the production of which 
the life of an ordinary vegetable ends4 
,as soon as the latter has borne seed1  
it dies1 or a period of its life comes  
to a termination4  ,in that endless     

series of compounds1 which begins with  
carbonic acid1 ammonia1 and water1 the  
sources of the nutrition of vegetables1 
and includes the most complex           
constituents of the animal brain1 there 
is no blank1 no interruption4 ,the first
 substance capable of affording         
nutriment to animals is the last product
 of the creative energy of vegetables4  
,the substance of cellular tissue and of
 membranes1 of the brain and nerves1    
these the vegetable cannot produce4     
,the seemingly miraculous in the        
productive agency of vegetables         
disappears in a great degree1 when we   
reflect that the production of the      
constituents of blood cannot appear more
 surprising than the occurrence of the  
fat of beef and mutton in cocoa beans1  
of human fat in olive-oil1 of the       
principal ingredient of butter in       
palm-oil1 and of horse fat and train-oil
 in certain oily seeds4     ,,letter    
,,ix   ,my dear ,sir1  ,the facts       
detailed in my last letter will satisfy 

you as to the manner in which the       
increase of mass in an animal1 that is1 
its growth1 is accomplished2 we have    
still to consider a most important      
question1 namely1 the function performed
 in the animal system by substances     
destitute of nitrogen2 such as sugar1   
starch1 gum1 pectine1 c4  ,the most     
extensive class of animals1 the         
graminivora1 cannot live without these  
substances2 their food must contain a   
certain amount of one or more of them1  
and if these compounds are not supplied1
 death quickly ensues4  ,this important 
inquiry extends also to the constituents
 of the food of carnivorous animals in  
the earliest periods of life2 for this  
food also contains substances1 which are
 not necessary for their support in the 
adult state4 ,the nutrition of the young
 of carnivora is obviously accomplished 
by means similar to those by which the  
graminivora are nourished2 their        
development is dependent on the supply  
of a fluid1 which the body of the mother

 secretes in the shape of milk4  ,milk  
contains only one nitrogenised          
constituent1 known under the name of    
caseine2 besides this1 its chief        
ingredients are butter 7fat71 and sugar 
of milk4 ,the blood of the young animal1
 its muscular fibre1 cellular tissue1   
nervous matter1 and bones1 must have    
derived their origin from the           
nitrogenised constituent of milk--the   
caseine2 for butter and sugar of milk   
contain no nitrogen4  ,now1 the analysis
 of caseine has led to the result1      
which1 after the details ,i have given1 
can hardly excite your surprise1 that   
this substance also is identical in     
composition with the chief constituents 
of blood1 fibrine and albumen4 ,nay     
more--a comparison of its properties    
with those of vegetable caseine has     
shown--that these two substances are    
identical in all their properties2      
insomuch1 that certain plants1 such as  
peas1 beans1 and lentils1 are capable of
 producing the same substance which is  

formed from the blood of the mother1 and
 employed in yielding the blood of the  
young animal4  ,the young animal1       
therefore1 receives in the form of      
caseine1--which is distinguished from   
fibrine and albumen by its great        
solubility1 and by not coagulating when 
heated1--the chief constituent of the   
mother's blood4 ,to convert caseine into
 blood no foreign substance is required1
 and in the conversion of the mother's  
blood into caseine1 no elements of the  
constituents of the blood have been     
separated4 ,when chemically examined1   
caseine is found to contain a much      
larger proportion of the earth of bones 
than blood does1 and that in a very     
soluble form1 capable of reaching every 
part of the body4 ,thus1 even in the    
earliest period of its life1 the        
development of the organs1 in which     
vitality resides1 is1 in the carnivorous
 animal1 dependent on the supply of a   
substance1 identical in organic         
composition with the chief constituents 

of its blood4  ,what1 then1 is the use  
of the butter and the sugar of milk8    
,how does it happen that these          
substances are indispensable to life8   
,butter and sugar of milk contain no    
fixed bases1 no soda nor potash4 ,sugar 
of milk has a composition closely allied
 to that of the other kinds of sugar1 of
 starch1 and of gum2 all of them contain
 carbon and the elements of water1 the  
latter precisely in the proportion to   
form water4  ,there is added1 therefore1
 by means of these compounds1 to the    
nitrogenised constituents of food1 a    
certain amount of carbon2 or1 as in the 
case of butter1 of carbon and hydrogen2 
that is1 an excess of elements1 which   
cannot possibly be employed in the      
production of blood1 because the        
nitrogenised substances contained in the
 food already contain exactly the amount
 of carbon which is required for the    
production of fibrine and albumen4  ,in 
an adult carnivorous animal1 which      
neither gains nor loses weight1         

perceptibly1 from day to day1 its       
nourishment1 the waste of organised     
tissue1 and its consumption of oxygen1  
stand to each other in a well-defined   
and fixed relation4  ,the carbon of the 
carbonic acid given off1 with that of   
the urine2 the nitrogen of the urine1   
and the hydrogen given off as ammonia   
and water2 these elements1 taken        
together1 must be exactly equal in      
weight to the carbon1 nitrogen1 and     
hydrogen of the metamorphosed tissues1  
and since these last are exactly        
replaced by the food1 to the carbon1    
nitrogen1 and hydrogen of the food4     
,were this not the case1 the weight of  
the animal could not possibly remain    
unchanged4  ,but1 in the young of the   
carnivora1 the weight does not remain   
unchanged2 on the contrary1 it increases
 from day to day by an appreciable      
quantity4  ,this fact presupposes1 that 
the assimilative process in the young   
animal is more energetic1 more intense1 
than the process of transformation in   

the existing tissues4 ,if both processes
 were equally active1 the weight of the 
body could not increase2 and were the   
waste by transformation greater1 the    
weight of the body would decrease4      
,now1 the circulation in the young      
animal is not weaker1 but1 on the       
contrary1 more rapid2 the respirations  
are more frequent2 and1 for equal bulks1
 the consumption of oxygen must be      
greater rather than smaller in the young
 than in the adult animal4 ,but1 since  
the metamorphosis of organised parts    
goes on more slowly1 there would ensue a
 deficiency of those substances1 the    
carbon and hydrogen of which are adapted
 for combination with oxygen2 because1  
in the carnivora1 nature has destined   
the new compounds1 produced by the      
metamorphosis of organised parts1 to    
furnish the necessary resistance to the 
action of the oxygen1 and to produce    
animal heat4 ,what is wanting for these 
purposes an ,infinite ,wisdom has       
supplied to the young in its natural    

food4  ,the carbon and hydrogen of      
butter1 and the carbon of the sugar of  
milk1 no part of either of which can    
yield blood1 fibrine1 or albumen1 are   
destined for the support of the         
respiratory process1 at an age when a   
greater resistance is opposed to the    
metamorphosis of existing organisms2 or1
 in other words1 to the production of   
compounds1 which1 in the adult state1   
are produced in quantity amply          
sufficient for the purpose of           
respiration4  ,the young animal receives
 the constituents of its blood in the   
caseine of the milk4 ,a metamorphosis of
 existing organs goes on1 for bile and  
urine are secreted2 the materials of the
 metamorphosed parts are given off in   
the form of urine1 of carbonic acid1 and
 of water2 but the butter and sugar of  
milk also disappear2 they cannot be     
detected in the faeces4  ,the butter and
 sugar of milk are given out in the form
 of carbonic acid and water1 and their  
conversion into oxidised products       

furnishes the clearest proof that far   
more oxygen is absorbed than is required
 to convert the carbon and hydrogen of  
the metamorphosed tissues into carbonic 
acid and water4  ,the change and        
metamorphosis of organised tissues going
 on in the vital process in the young   
animal1 consequently yield1 in a given  
time1 much less carbon and hydrogen in  
the form adapted for the respiratory    
process than correspond to the oxygen   
taken up in the lungs4 ,the substance of
 its organised parts would undergo a    
more rapid consumption1 and would       
necessarily yield to the action of the  
oxygen1 were not the deficiency of      
carbon and hydrogen supplied from       
another source4  ,the continued increase
 of mass1 or growth1 and the free and   
unimpeded development of the organs in  
the young animal1 are dependent on the  
presence of foreign substances1 which1  
in the nutritive process1 have no other 
function than to protect the            
newly-formed organs from the action of  

the oxygen4 ,the elements of these      
substances unite with the oxygen2 the   
organs themselves could not do so       
without being consumed2 that is1 growth1
 or increase of mass in the body1--the  
consumption of oxygen remaining the     
same1--would be utterly impossible4     
,the preceding considerations leave no  
doubt as to the purpose for which       
,nature has added to the food of the    
young of carnivorous mammalia substances
 devoid of nitrogen1 which their        
organism cannot employ for nutrition1   
strictly so called1 that is1 for the    
production of blood2 substances which   
may be entirely dispensed with in their 
nourishment in the adult state4 ,in the 
young of carnivorous birds1 the want of 
all motion is an obvious cause of       
diminished waste in the organised parts2
 hence1 milk is not provided for them4  
,the nutritive process in the carnivora 
thus presents itself under two distinct 
forms2 one of which we again meet with  
in the graminivora4  ,in graminivorous  

animals1 we observe1 that during their  
whole life1 their existence depends on a
 supply of substances having a          
composition identical with that of sugar
 of milk1 or closely resembling it4     
,everything that they consume as food   
contains a certain quantity of starch1  
gum1 or sugar1 mixed with other matters4
  ,the function performed in the vital  
process of the graminivora by these     
substances is indicated in a very clear 
and convincing manner1 when we take into
 consideration the very small relative  
amount of the carbon which these animals
 consume in the nitrogenised            
constituents of their food1 which bears 
no proportion whatever to the oxygen    
absorbed through the skin and lungs4  ,a
 horse1 for example1 can be kept in     
perfectly good condition1 if he obtain  
as food #ae lbs4 of hay and #d #a_/b    
lbs4 of oats daily4 ,if we now calculate
 the whole amount of nitrogen in these  
matters1 as ascertained by analysis 7#a 
#a_/b per cent4 in the hay1 #b4b per    

cent4 in the oats71 in the form of      
blood1 that is1 as fibrine and albumen1 
with the due proportion of water in     
blood 7#hj per cent471 the horse        
receives daily no more than #d #a_/b oz4
 of nitrogen1 corresponding to about #h 
lbs4 of blood4 ,but along with this     
nitrogen1 that is1 combined with it in  
the form of fibrine or albumen1 the     
animal receives only about #ad #a_/b oz4
 of carbon4  ,without going further into
 the calculation1 it will readily be    
admitted1 that the volume of air        
inspired and expired by a horse1 the    
quantity of oxygen consumed1 and1 as a  
necessary consequence1 the amount of    
carbonic acid given out by the animal1  
are much greater than in the respiratory
 process in man4 ,but an adult man      
consumes daily abut #ad oz4 of carbon1  
and the determination of ,boussingault1 
according to which a horse expires #gi  
oz4 daily1 cannot be very far from the  
truth4  ,in the nitrogenised            
constituents of his food1 therefore1 the

 horse receives rather less than the    
fifth part of the carbon which his      
organism requires for the support of the
 respiratory process2 and we see that   
the wisdom of the ,creator has added to 
his food the four-fifths which are      
wanting1 in various forms1 as starch1   
sugar1 c4 with which the animal must be 
supplied1 or his organism will be       
destroyed by the action of the oxygen4  
,it is obvious1 that in the system of   
the graminivora1 whose food contains so 
small a portion1 relatively1 of the     
constituents of the blood1 the process  
of metamorphosis in existing tissues1   
and consequently their restoration or   
reproduction1 must go on far less       
rapidly than in the carnivora4 ,were    
this not the case1 a vegetation a       
thousand times more luxuriant than the  
actual one would not suffice for their  
nourishment4 ,sugar1 gum1 and starch1   
would no longer be necessary to support 
life in these animals1 because1 in that 
case1 the products of the waste1 or     

metamorphosis of the organised tissues1 
would contain enough carbon to support  
the respiratory process4     ,,letter ,x
   ,my dear ,sir1  ,let me now apply the
 principles announced in the preceding  
letters to the circumstances of our own 
species4 ,man1 when confined to animal  
food1 requires for his support and      
nourishment extensive sources of food1  
even more widely extended than the lion 
and tiger1 because1 when he has the     
opportunity1 he kills without eating4   
,a nation of hunters1 on a limited      
space1 is utterly incapable of          
increasing its numbers beyond a certain 
point1 which is soon attained4 ,the     
carbon necessary for respiration must be
 obtained from the animals1 of which    
only a limited number can live on the   
space supposed4 ,these animals collect  
from plants the constituents of their   
organs and of their blood1 and yield    
them1 in turn1 to the savages who live  
by the chase alone4 ,they1 again1       
receive this food unaccompanied by those

 compounds1 destitute of nitrogen1      
which1 during the life of the animals1  
served to support the respiratory       
process4 ,in such men1 confined to an   
animal diet1 it is the carbon of the    
flesh and of the blood which must take  
the place of starch and sugar4  ,but #ae
 lbs4 of flesh contain no more carbon   
than #d lbs4 of starch1 and while the   
savage with one animal and an equal     
weight of starch should maintain life   
and health for a certain number of days1
 he would be compelled1 if confined to  
flesh alone1 in order to procure the    
carbon necessary for respiration1 during
 the same time1 to consume five such    
animals4  ,it is easy to see1 from these
 considerations1 how close the          
connection is between agriculture and   
the multiplication of the human species4
 ,the cultivation of our crops has      
ultimately no other object than the     
production of a maximum of those        
substances which are adapted for        
assimilation and respiration1 in the    

smallest possible space4 ,grain and     
other nutritious vegetables yield us1   
not only in starch1 sugar1 and gum1 the 
carbon which protects our organs from   
the action of oxygen1 and produces in   
the organism the heat which is essential
 to life1 but also in the form of       
vegetable fibrine1 albumen1 and caseine1
 our blood1 from which the other parts  
of our body are developed4  ,man1 when  
confined to animal food1 respires1 like 
the carnivora1 at the expense of the    
matters produced by the metamorphosis of
 organised tissues2 and1 just as the    
lion1 tiger1 hyaena1 in the cages of a  
menagerie1 are compelled to accelerate  
the waste of the organised tissues by   
incessant motion1 in order to furnish   
the matter necessary for respiration1   
so1 the savage1 for the very same       
object1 is forced to make the most      
laborious exertions1 and go through a   
vast amount of muscular exercise4 ,he is
 compelled to consume force merely in   
order to supply matter for respiration4 

,cultivation is the economy of force4   
,science teaches us the simplest means  
of obtaining the greatest effect with   
the smallest expenditure of power1 and  
with given means to produce a maximum of
 force4 ,the unprofitable exertion of   
power1 the waste of force in            
agriculture1 in other branches of       
industry1 in science1 or in social      
economy1 is characteristic of the savage
 state1 or of the want of knowledge4    
,in accordance with what ,i have already
 stated1 you will perceive that the     
substances of which the food of man is  
composed may be divided into two        
classes2 into nitrogenised and          
non-nitrogenised4 ,the former are       
capable of conversion into blood2 the   
latter are incapable of this            
transformation4  ,out of those          
substances which are adapted to the     
formation of blood1 are formed all the  
organised tissues4 ,the other class of  
substances1 in the normal state of      
health1 serve to support the process of 

respiration4 ,the former may be called  
the plastic elements of nutrition2 the  
latter1 elements of respiration4  ,among
 the former we reckon--    ,vegetable   
fibrine4   ,vegetable albumen4          
,vegetable caseine4   ,animal flesh4    
,animal blood4  ,among the elements of  
respiration in our food1 are--    ,fat4 
,pectine4   ,starch4 ,bassorine4   ,gum4
 ,wine4   ,cane sugar4 ,beer4   ,grape  
sugar4 ,spirits4   ,sugar of milk4  ,the
 most recent and exact researches have  
established as a universal fact1 to     
which nothing yet known is opposed1 that
 the nitrogenised constituents of       
vegetable food have a composition       
identical with that of the constituents 
of the blood4  ,no nitrogenised         
compound1 the composition of which      
differs from that of fibrine1 albumen1  
and caseine1 is capable of supporting   
the vital process in animals4  ,the     
animal organism unquestionably possesses
 the power of forming1 from the         
constituents of its blood1 the substance

 of its membranes and cellular tissue1  
of the nerves and brain1 and of the     
organic part of cartilages and bones4   
,but the blood must be supplied to it   
perfect in everything but its form--that
 is1 in its chemical composition4 ,if   
this be not done1 a period is rapidly   
put to the formation of blood1 and      
consequently to life4  ,this            
consideration enables us easily to      
explain how it happens that the tissues 
yielding gelatine or chondrine1 as1 for 
example1 the gelatine of skin or of     
bones1 are not adapted for the support  
of the vital process2 for their         
composition is different from that of   
fibrine or albumen4 ,it is obvious that 
this means nothing more than that those 
parts of the animal organism which form 
the blood do not possess the power of   
effecting a transformation in the       
arrangement of the elements of gelatine1
 or of those tissues which contain it4  
,the gelatinous tissues1 the gelatine of
 the bones1 the membranes1 the cells and

 the skin suffer1 in the animal body1   
under the influence of oxygen and       
moisture1 a progressive alteration2 a   
part of these tissues is separated1 and 
must be restored from the blood2 but    
this alteration and restoration are     
obviously confined within very narrow   
limits4  ,while1 in the body of a       
starving or sick individual1 the fat    
disappears and the muscular tissue takes
 once more the form of blood1 we find   
that the tendons and membranes retain   
their natural condition1 and the limbs  
of the dead body their connections1     
which depend on the gelatinous tissues4 
,on the other hand1 we see that the     
gelatine of bones devoured by a dog     
entirely disappears1 while only the bone
 earth is found in his excrements4 ,the 
same is true of man1 when fed on food   
rich in gelatine1 as1 for example1      
strong soup4 ,the gelatine is not to be 
found either in the urine or in the     
faeces1 and consequently must have      
undergone a change1 and must have served

 some purpose in the animal economy4 ,it
 is clear that the gelatine must be     
expelled from the body in a form        
different from that in which it was     
introduced as food4  ,when we consider  
the transformation of the albumen of the
 blood into a part of an organ composed 
of fibrine1 the identity in composition 
of the two substances renders the change
 easily conceivable4 ,indeed we find the
 change of a dissolved substance into an
 insoluble organ of vitality1 chemically
 speaking1 natural and easily explained1
 on account of this very identity of    
composition4 ,hence the opinion is not  
unworthy of a closer investigation1 that
 gelatine1 when taken in the dissolved  
state1 is again converted1 in the body1 
into cellular tissue1 membrane and      
cartilage2 that it may serve for the    
reproduction of such parts of these     
tissues as have been wasted1 and for    
their growth4  ,and when the powers of  
nutrition in the whole body are affected
 by a change of the health1 then1 even  

should the power of forming blood remain
 the same1 the organic force by which   
the constituents of the blood are       
transformed into cellular tissue and    
membranes must necessarily be enfeebled 
by sickness4 ,in the sick man1 the      
intensity of the vital force1 its power 
to produce metamorphoses1 must be       
diminished as well in the stomach as in 
all other parts of the body4 ,in this   
condition1 the uniform experience of    
practical physicians shows that         
gelatinous matters in a dissolved state 
exercise a most decided influence on the
 state of the health4 ,given in a form  
adapted for assimilation1 they serve to 
husband the vital force1 just as may be 
done1 in the case of the stomach1 by due
 preparation of the food in general4    
,brittleness in the bones of            
graminivorous animals is clearly owing  
to a weakness in those parts of the     
organism whose function it is to convert
 the constituents of the blood into     
cellular tissue and membrane2 and if we 

can trust to the reports of physicians  
who have resided in the ,east1 the      
,turkish women1 in their diet of rice1  
and in the frequent use of enemata of   
strong soup1 have united the conditions 
necessary for the formation both of     
cellular tissue and of fat4     ,,letter
 ,,xi   ,my dear ,sir1  ,in the immense1
 yet limited expanse of the ocean1 the  
animal and vegetable kingdoms are       
mutually dependent upon1 and successive 
to each other4 ,the animals obtain their
 constituent elements from the plants1  
and restore them to the water in their  
original form1 when they again serve as 
nourishment to a new generation of      
plants4  ,the oxygen which marine       
animals withdraw in their respiration   
from the air1 dissolved in sea water1 is
 returned to the water by the vital     
processes of sea plants2 that air is    
richer in oxygen than atmospheric air1  
containing #cb to #cc per cent4 ,oxygen1
 also1 combines with the products of the
 putrefaction of dead animal bodies1    

changes their carbon into carbonic acid1
 their hydrogen into water1 and their   
nitrogen assumes again the form of      
ammonia4  ,thus we observe in the ocean 
a circulation takes place without the   
addition or subtraction of any element1 
unlimited in duration1 although limited 
in extent1 inasmuch as in a confined    
space the nourishment of plants exists  
in a limited quantity4  ,we well know   
that marine plants cannot derive a      
supply of humus for their nourishment   
through their roots4 ,look at the great 
sea-tang1 the ,fucus giganteus3 this    
plant1 according to ,cook1 reaches a    
height of #cfj feet1 and a single       
specimen1 with its immense              
ramifications1 nourishes thousands of   
marine animals1 yet its root is a small 
body1 no larger than the fist4 ,what    
nourishment can this draw from a naked  
rock1 upon the surface of which there is
 no perceptible change8 ,it is quite    
obvious that these plants require only a
 hold1--a fastening to prevent a change 

of place1--as a counterpoise to their   
specific gravity1 which is less than    
that of the medium in which they float4 
,that medium provides the necessary     
nourishment1 and presents it to the     
surface of every part of the plant4     
,sea-water contains not only carbonic   
acid and ammonia1 but the alkaline and  
earthy phosphates and carbonates        
required by these plants for their      
growth1 and which we always find as     
constant constituents of their ashes4   
,all experience demonstrates that the   
conditions of the existence of marine   
plants are the same which are essential 
to terrestrial plants4 ,but the latter  
do not live like sea-plants1 in a medium
 which contains all their elements and  
surrounds with appropriate nourishment  
every part of their organs2 on the      
contrary1 they require two media1 of    
which one1 namely the soil1 contains    
those essential elements which are      
absent from the medium surrounding them1
 i4e4 the atmosphere4  ,is it possible  

that we could ever be in doubt          
respecting the office which the soil and
 its component parts subserve in the    
existence and growth of                 
vegetables8--that there should have been
 a time when the mineral elements of    
plants were not regarded as absolutely  
essential to their vitality8 ,has not   
the same circulation been observed on   
the surface of the earth which we have  
just contemplated in the ocean1--the    
same incessant change1 disturbance and  
restitution of equilibrium8  ,experience
 in agriculture shows that the          
production of vegetables on a given     
surface increases with the supply of    
certain matters1 originally parts of the
 soil which had been taken up from it by
 plants--the excrements of man and      
animals4 ,these are nothing more than   
matters derived from vegetable food1    
which in the vital processes of animals1
 or after their death1 assume again the 
form under which they originally        
existed1 as parts of the soil4 ,now1 we 

know that the atmosphere contains none  
of these substances1 and therefore can  
replace none2 and we know that their    
removal from a soil destroys its        
fertility1 which may be restored and    
increased by a new supply4  ,is it      
possible1 after so many decisive        
investigations into the origin of the   
elements of animals and vegetables1 the 
use of the alkalies1 of lime and the    
phosphates1 any doubt can exist as to   
the principles upon which a rational    
agriculture depends8 ,can the art of    
agriculture be based upon anything but  
the restitution of a disturbed          
equilibrium8 ,can it be imagined that   
any country1 however rich and fertile1  
with a flourishing commerce1 which for  
centuries exports its produce in the    
shape of grain and cattle1 will maintain
 its fertility1 if the same commerce    
does not restore1 in some form of       
manure1 those elements which have been  
removed from the soil1 and which cannot 
be replaced by the atmosphere8 ,must not

 the same fate await every such country 
which has actually befallen the once    
prolific soil of ,virginia1 now in many 
parts no longer able to grow its former 
staple productions--wheat and tobacco8  
,in the large towns of ,england the     
produce both of ,english and foreign    
agriculture is largely consumed2        
elements of the soil indispensable to   
plants do not return to the             
fields1--contrivances resulting from the
 manners and customs of ,english people1
 and peculiar to them1 render it        
difficult1 perhaps impossible1 to       
collect the enormous quantity of the    
phosphates which are daily1 as solid and
 liquid excrements1 carried into the    
rivers4 ,these phosphates1 although     
present in the soil in the smallest     
quantity1 are its most important mineral
 constituents4 ,it was observed that    
many ,english fields exhausted in that  
manner immediately doubled their        
produce1 as if by a miracle1 when       
dressed with bone earth imported from   

the ,continent4 ,but if the export of   
bones from ,germany is continued to the 
extent it has hitherto reached1 our soil
 must be gradually exhausted1 and the   
extent of our loss may be estimated1 by 
considering that one pound of bones     
contains as much phosphoric acid as a   
hundred-weight of grain4  ,the imperfect
 knowledge of ,nature and the properties
 and relations of matter possessed by   
the alchemists gave rise1 in their time1
 to an opinion that metals as well as   
plants could be produced from a seed4   
,the regular forms and ramifications    
seen in crystals1 they imagined to be   
the leaves and branches of metal plants2
 and as they saw the seed of plants     
grow1 producing root1 stem and leaves1  
and again blossoms1 fruit and seeds1    
apparently without receiving any supply 
of appropriate material1 they deemed it 
worthy of zealous inquiry to discover   
the seed of gold1 and the earth         
necessary for its development4 ,if the  
metal seeds were once obtained1 might   

they not entertain hopes of their       
growth8  ,such ideas could only be      
entertained when nothing was known of   
the atmosphere1 and its participation   
with the earth1 in administering to the 
vital processes of plants and animals4  
,modern chemistry indeed produces the   
elements of water1 and1 combining them1 
forms water anew2 but it does not create
 those elements--it derives them from   
water2 the new-formed artificial water  
has been water before4  ,many of our    
farmers are like the alchemists of      
old1--they are searching for the        
miraculous seed1--the means1 which1     
without any further supply of           
nourishment to a soil scarcely rich     
enough to be sprinkled with indigenous  
plants1 shall produce crops of grain a  
hundred-fold4  ,the experience of       
centuries1 nay1 of thousands of years1  
is insufficient to guard men against    
these fallacies2 our only security from 
these and similar absurdities must be   
derived from a correct knowledge of     

scientific principles4  ,in the first   
period of natural philosophy1 organic   
life was supposed to be derived from    
water only2 afterwards1 it was admitted 
that certain elements derived from the  
air must be superadded to the water2 but
 we now know that other elements must be
 supplied by the earth1 if plants are to
 thrive and multiply4  ,the amount of   
materials contained in the atmosphere1  
suited to the nourishment of plants1 is 
limited2 but it must be abundantly      
sufficient to cover the whole surface of
 the earth with a rich vegetation4      
,under the tropics1 and in those parts  
of our globe where the most genial      
conditions of fertility exist1--a       
suitable soil1 a moist atmosphere1 and a
 high temperature1--vegetation is       
scarcely limited by space2 and1 where   
the soil is wanting1 it is gradually    
supplied by the decaying leaves1 bark   
and branches of plants4 ,it is obvious  
there is no deficiency of atmospheric   
nourishment for plants in those regions1

 nor are these wanting in our own       
cultivated fields3 all that plants      
require for their development is        
conveyed to them by the incessant       
motions of the atmosphere4 ,the air     
between the tropics contains no more    
than that of the arctic zones2 and yet  
how different is the amount of produce  
of an equal surface of land in the two  
situations6  ,this is easily explicable4
 ,all the plants of tropical climates1  
the oil and wax palms1 the sugar cane1  
c41 contain only a small quantity of the
 elements of the blood necessary to the 
nutrition of animals1 as compared with  
our cultivated plants4 ,the tubers of   
the potato in ,chili1 its native        
country1 where the plant resembles a    
shrub1 if collected from an acre of     
land1 would scarcely suffice to maintain
 an ,irish family for a single day      
7,darwin74 ,the result of cultivation in
 those plants which serve as food1 is to
 produce in them those constituents of  
the blood4 ,in the absence of the       

elements essential to these in the soil1
 starch1 sugar and woody fibre1 are     
perhaps formed2 but no vegetable        
fibrine1 albumen1 or caseine4 ,if we    
intend to produce on a given surface of 
soil more of these latter matters than  
the plants can obtain from the          
atmosphere or receive from the soil of  
the same surface in its uncultivated and
 normal state1 we must create an        
artificial atmosphere1 and add the      
needed elements to the soil4  ,the      
nourishment which must be supplied in a 
given time to different plants1 in order
 to admit a free and unimpeded growth1  
is very unequal4  ,on pure sand1 on     
calcareous soil1 on naked rocks1 only a 
few genera of plants prosper1 and these 
are1 for the most part1 perennial       
plants4 ,they require1 for their slow   
growth1 only such minute quantities of  
mineral substances as the soil can      
furnish1 which may be totally barren for
 other species4 ,annual1 and especially 
summer plants1 grow and attain their    

perfection in a comparatively short     
time2 they therefore do not prosper on a
 soil which is poor in those mineral    
substances necessary to their           
development4 ,to attain a maximum in    
height in the short period of their     
existence1 the nourishment contained in 
the atmosphere is not sufficient4 ,if   
the end of cultivation is to be         
obtained1 we must create in the soil an 
artificial atmosphere of carbonic acid  
and ammonia2 and this surplus of        
nourishment1 which the leaves cannot    
appropriate from the air1 must be taken 
up by the corresponding organs1 i4e4 the
 roots1 from the soil4 ,but the ammonia1
 together with the carbonic acid1 are   
alone insufficient to become part of a  
plant destined to the nourishment of    
animals4 ,in the absence of the         
alkalies1 the phosphates and other      
earthy salts1 no vegetable fibrine1 no  
vegetable caseine1 can be formed4 ,the  
phosphoric acid of the phosphate of     
lime1 indispensable to the cerealia and 

other vegetables in the formation of    
their seeds1 is separated as an         
excrement1 in great quantities1 by the  
rind and barks of ligneous plants4  ,how
 different are the evergreen plants1 the
 cacti1 the mosses1 the ferns1 and the  
pines1 from our annual grasses1 the     
cerealia and leguminous vegetables6 ,the
 former1 at every time of the day during
 winter and summer1 obtain carbon       
through their leaves by absorbing       
carbonic acid which is not furnished by 
the barren soil on which they grow2     
water is also absorbed and retained by  
their coriaceous or fleshy leaves with  
great force4 ,they lose very little by  
evaporation1 compared with other plants4
 ,on the other hand1 how very small is  
the quantity of mineral substances which
 they withdraw from the soil during     
their almost constant growth in one     
year1 in comparison with the quantity   
which one crop of wheat of an equal     
weight receives in three months6  ,it is
 by means of moisture that plants       

receive the necessary alkalies and salts
 from the soil4 ,in dry summers a       
phenomenon is observed1 which1 when the 
importance of mineral elements to the   
life of a plant was unknown1 could not  
be explained4 ,the leaves of plants     
first developed and perfected1 and      
therefore nearer the surface of the     
soil1 shrivel up and become yellow1 lose
 their vitality1 and fall off while the 
plant is in an active state of growth1  
without any visible cause4 ,this        
phenomenon is not seen in moist years1  
nor in evergreen plants1 and but rarely 
in plants which have long and deep      
roots1 nor is it seen in perennials in  
autumn and winter4  ,the cause of this  
premature decay is now obvious4 ,the    
perfectly-developed leaves absorb       
continually carbonic acid and ammonia   
from the atmosphere1 which are converted
 into elements of new leaves1 buds1 and 
shoots2 but this metamorphosis cannot be
 effected without the aid of the        
alkalies1 and other mineral substances4 

,if the soil is moist1 the latter are   
continually supplied to an adequate     
amount1 and the plant retains its lively
 green colour2 but if this supply ceases
 from a want of moisture to dissolve the
 mineral elements1 a separation takes   
place in the plant itself4 ,the mineral 
constituents of the juice are withdrawn 
from the leaves already formed1 and are 
used for the formation of the young     
shoots2 and as soon as the seeds are    
developed1 the vitality of the leaves   
completely ceases4 ,these withered      
leaves contain only minute traces of    
soluble salts1 while the buds and shoots
 are very rich in them4  ,on the other  
hand1 it has been observed1 that where a
 soil is too highly impregnated with    
soluble saline materials1 these are     
separated upon the surface of the       
leaves4 ,this happens to culinary       
vegetables especially1 whose leaves     
become covered with a white crust4 ,in  
consequence of these exudations the     
plant sickens1 its organic activity     

decreases1 its growth is disturbed2 and 
if this state continues long1 the plant 
dies4 ,this is most frequently seen in  
foliaceous plants1 the large surfaces of
 which evaporate considerable quantities
 of water4 ,carrots1 pumpkins1 peas1 c41
 are frequently thus diseased1 when1    
after dry weather1 the plant being near 
its full growth1 the soil is moistened  
by short showers1 followed again by dry 
weather4 ,the rapid evaporation carries 
off the water absorbed by the root1 and 
this leaves the salts in the plant in a 
far greater quantity than it can        
assimilate4 ,these salts effloresce upon
 the surface of the leaves1 and if they 
are herbaceous and juicy1 produce an    
effect upon them as if they had been    
watered with a solution containing a    
greater quantity of salts than their    
organism can bear4  ,of two plants of   
the same species1 this disease befalls  
that which is nearest its perfection2 if
 one should have been planted later1 or 
be more backward in its development1 the

 same external cause which destroys the 
one will contribute to the growth of the
 other4     ,,letter ,,xii   ,my dear   
,sir1  ,having now occupied several     
letters with the attempt to unravel1 by 
means of chemistry1 some of the most    
curious functions of the animal body1   
and1 as ,i hope1 made clear to you the  
distinctions between the two kinds of   
constituent elements in food1 and the   
purposes they severally subserve in     
sustaining life1 let me now direct your 
attention to a scarcely less interesting
 and equally important subject--the     
means of obtaining from a given surface 
of the earth the largest amount of      
produce adapted to the food of man and  
animals4  ,agriculture is both a science
 and an art4 ,the knowledge of all the  
conditions of the life of vegetables1   
the origin of their elements1 and the   
sources of their nourishment1 forms its 
scientific basis4  ,from this knowledge 
we derive certain rules for the exercise
 of the ,,art1 the principles upon which

 the mechanical operations of farming   
depend1 the usefulness or necessity of  
these for preparing the soil to support 
the growth of plants1 and for removing  
every obnoxious influence4 ,no          
experience1 drawn from the exercise of  
the art1 can be opposed to true         
scientific principles1 because the      
latter should include all the results of
 practical operations1 and are in some  
instances solely derived therefrom4     
,theory must correspond with experience1
 because it is nothing more than the    
reduction of a series of phenomena to   
their last causes4  ,a field in which we
 cultivate the same plant for several   
successive years becomes barren for that
 plant in a period varying with the     
nature of the soil3 in one field it will
 be in three1 in another in seven1 in a 
third in twenty1 in a fourth in a       
hundred years4 ,one field bears wheat1  
and no peas2 another beans or turnips1  
but no tobacco2 a third gives a         
plentiful crop of turnips1 but will not 

bear clover4 ,what is the reason that a 
field loses its fertility for one plant1
 the same which at first flourished     
there8 ,what is the reason one kind of  
plant succeeds in a field where another 
fails8  ,these questions belong to      
,science4  ,what means are necessary to 
preserve to a field its fertility for   
one and the same plant8--what to render 
one field fertile for two1 for three1   
for all plants8  ,these last questions  
are put by ,art1 but they cannot be     
answered by ,art4  ,if a farmer1 without
 the guidance of just scientific        
principles1 is trying experiments to    
render a field fertile for a plant which
 it otherwise will not bear1 his        
prospect of success is very small4      
,thousands of farmers try such          
experiments in various directions1 the  
result of which is a mass of practical  
experience forming a method of          
cultivation which accomplishes the      
desired end for certain places2 but the 
same method frequently does not succeed1

 it indeed ceases to be applicable to a 
second or third place in the immediate  
neighbourhood4 ,how large a capital1 and
 how much power1 are wasted in these    
experiments6 ,very different1 and far   
more secure1 is the path indicated by   
,,science2 it exposes us to no danger of
 failing1 but1 on the contrary1 it      
furnishes us with every guarantee of    
success4 ,if the cause of failure--of   
barrenness in the soil for one or two   
plants--has been discovered1 means to   
remedy it may readily be found4  ,the   
most exact observations prove that the  
method of cultivation must vary with the
 geognostical condition of the subsoil4 
,in basalt1 graywacke1 porphyry1        
sandstone1 limestone1 c41 are certain   
elements indispensable to the growth of 
plants1 and the presence of which       
renders them fertile4 ,this fully       
explains the difference in the necessary
 methods of culture for different       
places2 since it is obvious that the    
essential elements of the soil must vary

 with the varieties of composition of   
the rocks1 from the disintegration of   
which they originated4  ,wheat1 clover1 
turnips1 for example1 each require      
certain elements from the soil2 they    
will not flourish where the appropriate 
elements are absent4 ,science teaches us
 what elements are essential to every   
species of plants by an analysis of     
their ashes4 ,if therefore a soil is    
found wanting in any of those elements1 
we discover at once the cause of its    
barrenness1 and its removal may now be  
readily accomplished4  ,the empiric     
attributes all his success to the       
mechanical operations of agriculture2 he
 experiences and recognises their value1
 without inquiring what are the causes  
of their utility1 their mode of action3 
and yet this scientific knowledge is of 
the highest importance for regulating   
the application of power and the        
expenditure of capital1--for insuring   
its economical expenditure and the      
prevention of waste4 ,can it be imagined

 that the mere passing of the           
ploughshare or the harrow through the   
soil--the mere contact of the iron--can 
impart fertility miraculously8 ,nobody1 
perhaps1 seriously entertains such an   
opinion4 ,nevertheless1 the modus       
operandi of these mechanical operations 
is by no means generally understood4    
,the fact is quite certain1 that careful
 ploughing exerts the most favourable   
influence3 the surface is thus          
mechanically divided1 changed1          
increased1 and renovated2 but the       
ploughing is only auxiliary to the end  
sought4  ,in the effects of time1 in    
what in ,agriculture are technically    
called fallows--the repose of the       
fields--we recognise by science certain 
chemical actions1 which are continually 
exercised by the elements of the        
atmosphere upon the whole surface of our
 globe4 ,by the action of its oxygen and
 its carbonic acid1 aided by water1     
rain1 changes of temperature1 c41       
certain elementary constituents of      

rocks1 or of their ruins1 which form the
 soil capable of cultivation1 are       
rendered soluble in water1 and          
consequently become separable from all  
their insoluble parts4  ,these chemical 
actions1 poetically denominates the     
tooth of time1 destroy all the works of 
man1 and gradually reduce the hardest   
rocks to the condition of dust4 ,by     
their influence the necessary elements  
of the soil become fitted for           
assimilation by plants2 and it is       
precisely the end which is obtained by  
the mechanical operations of farming4   
,they accelerate the decomposition of   
the soil1 in order to provide a new     
generation of plants with the necessary 
elements in a condition favourable to   
their assimilation4 ,it is obvious that 
the rapidity of the decomposition of a  
solid body must increase with the       
extension of its surface2 the more      
points of contact we offer in a given   
time to the external chemical agent1 the
 more rapid will be its action4  ,the   

chemist1 in order to prepare a mineral  
for analysis1 to decompose it1 or to    
increase the solubility of its elements1
 proceeds in the same way as the farmer 
deals with his fields--he spares no     
labour in order to reduce it to the     
finest powder2 he separates the         
impalpable from the coarser parts by    
washing1 and repeats his mechanical     
bruising and trituration1 being assured 
his whole process will fail if he is    
inattentive to this essential and       
preliminary part of it4  ,the influence 
which the increase of surface exercises 
upon the disintegration of rocks1 and   
upon the chemical action of air and     
moisture1 is strikingly illustrated upon
 a large scale in the operations pursued
 in the gold-mines of ,yaquil1 in       
,chili4 ,these are described in a very  
interesting manner by ,darwin4 ,the rock
 containing the gold ore is pounded by  
mills into the finest powder2 this is   
subjected to washing1 which separates   
the lighter particles from the metallic2

 the gold sinks to the bottom1 while a  
stream of water carries away the lighter
 earthy parts into ponds1 where it      
subsides to the bottom as mud4 ,when    
this deposit has gradually filled up the
 pond1 this mud is taken out and piled  
in heaps1 and left exposed to the action
 of the atmosphere and moisture4 ,the   
washing completely removes all the      
soluble part of the disintegrated rock2 
the insoluble part1 moreover1 cannot    
undergo any further change while it is  
covered with water1 and so excluded from
 the influence of the atmosphere at the 
bottom of the pond4 ,but being exposed  
at once to the air and moisture1 a      
powerful chemical action takes place in 
the whole mass1 which becomes indicated 
by an efflorescence of salts covering   
the whole surface of the heaps in       
considerable quantity4 ,after being     
exposed for two or three years1 the mud 
is again subjected to the same process  
of washing1 and a considerable quantity 
of gold is obtained1 this having been   

separated by the chemical process of    
decomposition in the mass4 ,the exposure
 and washing of the same mud is repeated
 six or seven times1 and at every       
washing it furnishes a new quantity of  
gold1 although its amount diminishes    
every time4  ,precisely similar is the  
chemical action which takes place in the
 soil of our fields2 and we accelerate  
and increase it by the mechanical       
operations of our agriculture4 ,by these
 we sever and extend the surface1 and   
endeavour to make every atom of the soil
 accessible to the action of the        
carbonic acid and oxygen of the         
atmosphere4 ,we thus produce a stock of 
soluble mineral substances1 which serves
 as nourishment to a new generation of  
plants1 materials which are             
indispensable to their growth and       
prosperity4     ,,letter ,,xiii   ,my   
dear ,sir1  ,having in my last letter   
spoken of the general principles upon   
which the science and art of agriculture
 must be based1 let me now direct your  

attention to some of those particulars  
between chemistry and agriculture1 and  
demonstrate the impossibility of        
perfecting the important art of rearing 
food for man and animals1 without a     
profound knowledge of our science4  ,all
 plants cultivated as food require for  
their healthy sustenance the alkalies   
and alkaline earths1 each in a certain  
proportion2 and in addition to these1   
the cerealia do not succeed in a soil   
destitute of silica in a soluble        
condition4 ,the combinations of this    
substance found as natural productions1 
namely1 the silicates1 differ greatly in
 the degree of facility with which they 
undergo decomposition1 in consequence of
 the unequal resistance opposed by their
 integral parts to the dissolving power 
of the atmospheric agencies4 ,thus the  
granite of ,corsica degenerates into a  
powder in a time which scarcely suffices
 to deprive the polished granite of     
,heidelberg of its lustre4  ,some soils 
abound in silicates so readily          

decomposable1 that in every one or two  
years1 as much silicate of potash       
becomes soluble and fitted for          
assimilation as is required by the      
leaves and straw of a crop of wheat4 ,in
 ,hungary1 extensive districts are not  
uncommon where wheat and tobacco have   
been grown alternately upon the same    
soil for centuries1 the land never      
receiving back any of those mineral     
elements which were withdrawn in the    
grain and straw4 ,on the other hand1    
there are fields in which the necessary 
amount of soluble silicate of potash for
 a single crop of wheat is not separated
 from the insoluble masses in the soil  
in less than two1 three1 or even more   
years4  ,the term fallow1 in            
,agriculture1 designates that period in 
which the soil1 left to the influence of
 the atmosphere1 becomes enriched with  
those soluble mineral constituents4     
,fallow1 however1 does not generally    
imply an entire cessation of            
cultivation1 but only an interval in the

 growth of the cerealia4 ,that store of 
silicates and alkalies which is the     
principal condition of their success is 
obtained1 if potatoes or turnips are    
grown upon the same fields in the       
intermediate periods1 since these crops 
do not abstract a particle of silica1   
and therefore leave the field equally   
fertile for the following crop of wheat4
  ,the preceding remarks will render it 
obvious to you1 that the mechanical     
working of the soil is the simplest and 
cheapest method of rendering the        
elements of nutrition contained in it   
accessible to plants4  ,but it may be   
asked1 ,are there not other means of    
decomposing the soil besides its        
mechanical subdivision8--are there not  
substances1 which by their chemical     
operation will equally well or better   
render its constituents suitable for    
entering into vegetable organisms8 ,yes3
 we certainly possess such substances1  
and one of them1 namely1 quick-lime1 has
 been employed for the last century past

 in ,england for this purpose2 and it   
would be difficult to find a substance  
better adapted to this service1 as it is
 simple1 and in almost all localities   
cheap and easily accessible4  ,in order 
to obtain correct views respecting the  
effect of quick-lime upon the soil1 let 
me remind you of the first process      
employed by the chemist when he is      
desirous of analysing a mineral1 and for
 this purpose wishes to bring its       
elements into a soluble state4 ,let the 
mineral to be examined be1 for instance1
 feldspar2 this substance1 taken alone1 
even when reduced to the finest powder1 
requires for its solution to be treated 
with an acid for weeks or months2 but if
 we first mix it with quick-lime1 and   
expose the mixture to a moderately      
strong heat1 the lime enters into       
chemical combination with certain       
elements of the feldspar1 and its alkali
 7potass7 is set free4 ,and now the     
acid1 even without heat1 dissolves not  
only the lime1 but also so much of the  

silica of the feldspar as to form a     
transparent jelly4 ,the same effect     
which the lime in this process1 with the
 aid of heat1 exerts upon the feldspar1 
it produces when it is mixed with the   
alkaline argillaceous silicates1 and    
they are for a long time kept together  
in a moist state4  ,common potters'     
clay1 or pipe-clay1 diffused through    
water1 and added to milk of lime1       
thickens immediately upon mixing2 and if
 the mixture is kept for some months1   
and then treated with acid1 the clay    
becomes gelatinous1 which would not     
occur without the admixture with the    
lime4 ,the lime1 in combining with the  
elements of the clay1 liquifies it2 and1
 what is more remarkable1 liberates the 
greater part of its alkalies4 ,these    
interesting facts were first observed by
 ,fuchs1 at ,munich3 they have not only 
led to a more intimate knowledge of the 
nature and properties of the hydraulic  
cements1 but1 what is far more          
important1 they explain the effects of  

caustic lime upon the soil1 and guide   
the agriculturist in the application of 
an invaluable means of opening it1 and  
setting free its alkalies--substances so
 important1 nay1 so indispensable to his
 crops4  ,in the month of ,october the  
fields of ,yorkshire and ,oxfordshire   
look as it they were covered with snow4 
,whole square miles are seen whitened   
over with quicklime1 which during the   
moist winter months1 exercises its      
beneficial influence upon the stiff1    
clayey soil1 of those counties4         
,according to the humus theory1         
quick-lime ought to exert the most      
noxious influence upon the soil1 because
 all organic matters contained in it are
 destroyed by it1 and rendered incapable
 of yielding their humus to a new       
vegetation4 ,the facts are indeed       
directly contrary to this now abandoned 
theory3 the fertility of the soil is    
increased by the lime4 ,the cerealia    
require the alkalies and alkaline       
silicates1 which the action of the lime 

renders fit for assimilation by the     
plants4 ,if1 in addition to these1 there
 is any decaying organic matter present 
in the soil supplying carbonic acid1 it 
may facilitate their development2 but it
 is not essential to their growth4 ,if  
we furnish the soil with ammonia1 and   
the phosphates1 which are indispensable 
to the cerealia1 with the alkaline      
silicates1 we have all the conditions   
necessary to ensure an abundant harvest4
 ,the atmosphere is an inexhaustible    
store of carbonic acid4  ,a no less     
favourable influence than that of lime  
is exercised upon the soil of peaty land
 by the mere act of burning it3 this    
greatly enhances its fertility4 ,we have
 not long been acquainted with the      
remarkable change which the properties  
of clay undergo by burning4 ,the        
observation was first made in the       
process of analysing the clay silicates4
 ,many of these1 in their natural state1
 are not acted on by acids1 but they    
become perfectly soluble if heated to   

redness before the application of the   
acid4 ,this property belongs to potters'
 clay1 pipe-clay1 loam1 and many        
different modifications of clay in      
soils4 ,in their natural state they may 
be boiled in concentrated sulphuric     
acid1 without sensible change2 but if   
feebly burned1 as is done with the      
pipe-clay in many alum manufactories1   
they dissolve in the acid with the      
greatest facility1 the contained silica 
being separated like jelly in a soluble 
state4 ,potters' clay belongs to the    
most sterile kinds of soil1 and yet it  
contains within itself all the          
constituent elements essential to a most
 luxurious growth of plants2 but their  
mere presence is insufficient to secure 
this end4 ,the soil must be accessible  
to the atmosphere1 to its oxygen1 to its
 carbonic acid2 these must penetrate it1
 in order to secure the conditions      
necessary to a happy and vigorous       
development of the roots4 ,the elements 
present must be brought into that       

peculiar state of combination which will
 enable them to enter into plants4      
,plastic clay is wanting in these       
properties2 but they are imparted to it 
by a feeble calcination4  ,at ,hardwicke
 ,court1 near ,gloucester1 ,i have seen 
a garden 7,mr4 ,baker's7 consisting of a
 stiff clay1 which was perfectly        
sterile1 become by mere burning         
extremely fertile4 ,the operation was   
extended to a depth of three feet4 ,this
 was an expensive process1 certainly2   
but it was effectual4  ,the great       
difference in the properties of burnt   
and unburnt clay is illustrated by what 
is seen in brick houses1 built in moist 
situations4 ,in the town of ,flanders1  
for instance1 where most buildings are  
of brick1 effloresences of salts cover  
the surfaces of the walls1 like a white 
nap1 within a few days after they are   
erected4 ,if this saline incrustation is
 washed away by the rain1 it soon       
re-appears2 and this is even observed on
 walls which1 like the gateway of       

,lisle1 have been erected for centuries4
 ,these saline incrustations consist of 
carbonates and sulphates1 with alkaline 
bases2 and it is well known these act an
 important part in vegetation4 ,the     
influence of lime in their production is
 manifested by their appearing first at 
the place where the mortar and brick    
come into contact4  ,it will now be     
obvious to you1 that in a mixture of    
clay with lime1 all the conditions exist
 for the solution of the silicated clay1
 and the solubility of the alkaline     
silicates4 ,the lime gradually          
dissolving in water charged with        
carbonic acid1 acts like milk of lime   
upon the clay4 ,this explains also the  
favourable influence which marl 7by     
which term all those varieties of clay  
rich in chalk are designated7 exerts    
upon most kinds of soil4 ,there are     
marly soils which surpass all others in 
fertility for all kinds of plants2 but  
,i believe marl in a burnt state must be
 far more effective1 as well as other   

materials possessing a similar          
composition2 as1 for instance1 those    
species of limestone which are adapted  
to the preparation of hydraulic         
cements1--for these carry to the soil   
not only the alkaline bases useful to   
plants1 but also silica in a state      
capable of assimilation4  ,the ashes of 
coals and lignite are also excellent    
means of ameliorating the soil1 and they
 are used in many places for this       
purpose4 ,the most suitable may be      
readily known by their property of      
forming a gelatinous mass when treated  
with acids1 or by becoming1 when mixed  
with cream of lime1 like hydraulic      
cement1--solid and hard as stone4  ,i   
have now1 ,i trust1 explained to your   
satisfaction1 that the mechanical       
operations of agriculture--the          
application of lime and chalk to lands1 
and the burning of clay--depend upon one
 and the same scientific principle3 they
 are means of accelerating the          
decomposition of the alkaline clay      

silicates1 in order to provide plants1  
at the beginning of a new vegetation1   
with certain inorganic matters          
indispensable for their nutrition4      
,,letter ,,xiv   ,my dear ,sir1  ,i     
treated1 in my last letter1 of the means
 of improving the condition of the soil 
for agricultural purposes by mechanical 
operations and mineral agents4 ,i have  
now to speak of the uses and effects of 
animal exuviae1 and vegetable matters or
 manures--properly so called4  ,in order
 to understand the nature of these1 and 
the peculiarity of their influence upon 
our fields1 it is highly important to   
keep in mind the source whence they are 
derived4  ,it is generally known1 that  
if we deprive an animal of food1 the    
weight of its body diminishes during    
every moment of its existence4 ,if this 
abstinence is continued for some time1  
the diminution becomes apparent to the  
eye2 all the fat of the body disappears1
 the muscles decrease in firmness and   
bulk1 and1 if the animal is allowed to  

die starved1 scarcely anything but skin1
 tendon1 and bones1 remain4 ,this       
emaciation which occurs in a body       
otherwise healthy1 demonstrates to us1  
that during the life of an animal every 
part of its living substance is         
undergoing a perpetual change2 all its  
component parts1 assuming the form of   
lifeless compounds1 are thrown off by   
the skin1 lungs1 and urinary system1    
altered more or less by the secretory   
organs4 ,this change in the living body 
is intimately connected with the process
 of respiration2 it is1 in truth1       
occasioned by the oxygen of the         
atmosphere in breathing1 which combines 
with all the various matters within the 
body4 ,at every inspiration a quantity  
of oxygen passes into the blood in the  
lungs1 and unites with its elements2 but
 although the weight of the oxygen thus 
daily entering into the body amounts to 
#cb or more ounces1 yet the weight of   
the body is not thereby increased4      
,exactly as much oxygen as is imbibed in

 inspiration passes off in expiration1  
in the form of carbonic acid and water2 
so that with every breath the amount of 
carbon and hydrogen in the body is      
diminished4 ,but the emaciation--the    
loss of weight by starvation--does not  
simply depend upon the separation of the
 carbon and hydrogen2 but all the other 
substances which are in combination with
 these elements in the living tissues   
pass off in the secretions4 ,the        
nitrogen undergoes a change1 and is     
thrown out of the system by the kidneys4
 ,their secretion1 the urine1 contains  
not only a compound rich in nitrogen1   
namely urea1 but the sulphur of the     
tissues in the form of a sulphate1 all  
the soluble salts of the blood and      
animal fluids1 common salt1 the         
phosphates1 soda and potash4 ,the carbon
 and hydrogen of the blood1 of the      
muscular fibre1 and of all the animal   
tissues which can undergo change1 return
 into the atmosphere4 ,the nitrogen1 and
 all the soluble inorganic elements are 

carried to the earth in the urine4      
,these changes take place in the healthy
 animal body during every moment of     
life2 a waste and loss of substance     
proceeds continually2 and if this loss  
is to be restored1 and the original     
weight and substance repaired1 an       
adequate supply of materials must be    
furnished1 from whence the blood and    
wasted tissues may be regenerated4 ,this
 supply is obtained from the food4  ,in 
an adult person in a normal or healthy  
condition1 no sensible increase or      
decrease of weight occurs from day to   
day4 ,in youth the weight of the body   
increases1 whilst in old age it         
decreases4 ,there can be no doubt that  
in the adult1 the food has exactly      
replaced the loss of substance3 it has  
supplied just so much carbon1 hydrogen1 
nitrogen1 and other elements1 as have   
passed through the skin1 lungs1 and     
urinary organs4 ,in youth the supply is 
greater than the waste4 ,part of the    
elements of the food remain to augment  

the bulk of the body4 ,in old age the   
waste is greater than the supply1 and   
the body diminishes4 ,it is             
unquestionable1 that1 with the exception
 of a certain quantity of carbon and    
hydrogen1 which are secreted through the
 skin and lungs1 we obtain1 in the solid
 and fluid excrements of man and        
animals1 all the elements of their food4
  ,we obtain daily1 in the form of urea1
 all the nitrogen taken in the food both
 of the young and the adult2 and        
further1 in the urine1 the whole amount 
of the alkalies1 soluble phosphates and 
sulphates1 contained in all the various 
aliments4 ,in the solid excrements are  
found all those substances taken in the 
food which have undergone no alteration 
in the digestive organs1 all            
indigestible matters1 such as woody     
fibre1 the green colouring matter of    
leaves 7 chlorophyle71 wax1 c4          
,physiology teaches us1 that the process
 of nutrition in animals1 that is1 their
 increase of bulk1 or the restoration of

 wasted parts1 proceeds from the blood4 
,the purpose of digestion and           
assimilation is to convert the food into
 blood4 ,in the stomach and intestines1 
therefore1 all those substances in the  
food capable of conversion into blood   
are separated from its other            
constituents2 in other words1 during the
 passage of the food through the        
intestinal canal there is a constant    
absorption of its nitrogen1 since only  
azotised substances are capable of      
conversion into blood2 and therefore the
 solid excrements are destitute of that 
element1 except only a small portion1 in
 the constitution of that secretion     
which is formed to facilitate their     
passage4 ,with the solid excrements1 the
 phosphates of lime and magnesia1 which 
were contained in the food and not      
assimilated1 are carried off1 these     
salts being insoluble in water1 and     
therefore not entering the urine4  ,we  
may obtain a clear insight into the     
chemical constitution of the solid      

excrements without further              
investigation1 by comparing the faeces  
of a dog with his food4 ,we give that   
animal flesh and bones--substances rich 
in azotised matter--and we obtain1 as   
the last product of its digestion1 a    
perfectly white excrement1 solid while  
moist1 but becoming in dry air a powder4
 ,this is the phosphate of lime of the  
bones1 with scarcely one per cent4 of   
foreign organic matter4  ,thus we see   
that in the solid and fluid excrements  
of man and animals1 all the nitrogen--in
 short1 all the constituent ingredients 
of the consumed food1 soluble and       
insoluble1 are returned2 and as food is 
primarily derived from the fields1 we   
possess in those excrements all the     
ingredients which we have taken from it 
in the form of seeds1 roots1 or herbs4  
,one part of the crops employed for     
fattening sheep and cattle is consumed  
by man as animal food2 another part is  
taken directly--as flour1 potatoes1     
green vegetables1 c42 a third portion   

consists of vegetable refuse1 and straw 
employed as litter4 ,none of the        
materials of the soil need be lost4 ,we 
can1 it is obvious1 get back all its    
constituent parts which have been       
withdrawn therefrom1 as fruits1 grain   
and animals1 in the fluid and solid     
excrements of man1 and the bones1 blood 
and skins of the slaughtered animals4   
,it depends upon ourselves to collect   
carefully all these scattered elements1 
and to restore the disturbed equilibrium
 of composition in the soil4 ,we can    
calculate exactly how much and which of 
the component parts of the soil we      
export in a sheep or an ox1 in a quarter
 of barley1 wheat or potatoes1 and we   
can discover1 from the known composition
 of the excrements of man and animals1  
how much we have to supply to restore   
what is lost to our fields4  ,if1       
however1 we could procure from other    
sources the substances which give to the
 exuviae of man and animals their value 
in agriculture1 we should not need the  

latter4 ,it is quite indifferent for our
 purpose whether we supply the ammonia  
7the source of nitrogen7 in the form of 
urine1 or in that of a salt derived from
 coal-tar2 whether we derive the        
phosphate of lime from bones1 apatite1  
or fossil excrements 7the coprolithes74 
,the principal problem for agriculture  
is1 how to replace those substances     
which have been taken from the soil1 and
 which cannot be furnished by the       
atmosphere4 ,if the manure supplies an  
imperfect compensation for this loss1   
the fertility of a field or of a country
 decreases2 if1 on the contrary1 more   
are given to the fields1 their fertility
 increases4  ,an importation of urine1  
or of solid excrements1 from a foreign  
country1 is equivalent to an importation
 of grain and cattle4 ,in a certain     
time1 the elements of those substances  
assume the form of grain1 or of fodder1 
then become flesh and bones1 enter into 
the human body1 and return again day by 
day to the form they originally         

possessed4  ,the only real loss of      
elements we are unable to prevent is of 
the phosphates1 and these1 in accordance
 with the customs of all modern nations1
 are deposited in the grave4 ,for the   
rest1 every part of that enormous       
quantity of food which a man consumes   
during his lifetime 7 say in sixty or   
seventy years71 which was derived from  
the fields1 can be obtained and returned
 to them4 ,we know with absolute        
certainty1 that in the blood of a young 
or growing animal there remains a       
certain quantity of phosphate of lime   
and of the alkaline phosphates1 to be   
stored up and to minister to the growth 
of the bones and general bulk of the    
body1 and that1 with the exception of   
this very small quantity1 we receive    
back1 in the solid and fluid excrements1
 all the salts and alkaline bases1 all  
the phosphate of lime and magnesia1 and 
consequently all the inorganic elements 
which the animal consumes in its food4  
,we can thus ascertain precisely the    

quantity1 quality1 and composition of   
animal excrements1 without the trouble  
of analysing them4 ,if we give a horse  
daily #d #a_/b pounds' weight of oats1  
and #ae pounds of hay1 and knowing that 
oats give #d per cent4 and hay #i per   
cent4 of ashes1 we can calculate that   
the daily excrements of the horse will  
contain #ba ounces of inorganic matter  
which was drawn from the fields4 ,by    
analysis we can determine the exact     
relative amount of silica1 of           
phosphates1 and of alkalies1 contained  
in the ashes of the oats and of the hay4
  ,you will now understand that the     
constituents of the solid parts of      
animal excrements1 and therefore their  
qualities as manure1 must vary with the 
nature of the creature's food4 ,if we   
feed a cow upon beetroot1 or potatoes1  
without hay1 straw or grain1 there will 
be no silica in her solid excrements1   
but there will be phosphate of lime and 
magnesia4 ,her fluid excrements will    
contain carbonate of potash and soda1   

together with compounds of the same     
bases with inorganic acids4 ,in one     
word1 we have1 in the fluid excrements1 
all the soluble parts of the ashes of   
the consumed food2 and in the solid     
excrements1 all those parts of the ashes
 which are insoluble in water4  ,if the 
food1 after burning1 leaves behind ashes
 containing soluble alkaline phosphates1
 as is the case with bread1 seeds of all
 kinds1 and flesh1 we obtain from the   
animal by which they are consumed a     
urine holding in solution these         
phosphates4 ,if1 however1 the ashes of  
food contain no alkaline phosphates1 but
 abound in insoluble earthy phosphates1 
as hay1 carrots1 and potatoes1 the urine
 will be free from alkaline phosphates1 
but the earthy phosphates will be found 
in the faeces4 ,the urine of man1 of    
carnivorous and graminivorous animals1  
contains alkaline phosphates2 that of   
herbivorous animals is free from these  
salts4  ,the analysis of the excrements 
of man1 of the piscivorous birds 7as the

 guano71 of the horse1 and of cattle1   
furnishes us with the precise knowledge 
of the salts they contain1 and          
demonstrates1 that in those excrements1 
we return to the fields the ashes of the
 plants which have served as food1--the 
soluble and insoluble salts and earths  
indispensable to the development of     
cultivated plants1 and which must be    
furnished to them by a fertile soil4    
,there can be no doubt that1 in         
supplying these excrements to the soil1 
we return to it those constituents which
 the crops have removed from it1 and we 
renew its capability of nourishing new  
crops3 in one word1 we restore the      
disturbed equilibrium2 and consequently1
 knowing that the elements of the food  
derived from the soil enter into the    
urine and solid excrements of the       
animals it nourishes1 we can with the   
greatest facility determine the exact   
value of the different kinds of manure4 
,thus the excrements of pigs which we   
have fed with peas and potatoes are     

principally suited for manuring crops of
 potatoes and peas4 ,in feeding a cow   
upon hay and turnips1 we obtain a manure
 containing the inorganic elements of   
grasses and turnips1 and which is       
therefore preferable for manuring       
turnips4 ,the excrement of pigeons      
contains the mineral elements of grain2 
that of rabbits1 the elements of herbs  
and kitchen vegetables4 ,the fluid and  
solid excrements of man1 however1       
contain the mineral elements of grain   
and seeds in the greatest quantity4     
,,letter ,,xv   ,my dear ,sir1  ,you are
 now acquainted with my opinions        
respecting the effects of the           
application of mineral agents to our    
cultivated fields1 and also the         
rationale of the influence of the       
various kinds of manures2 you will1     
therefore1 now readily understand what  
,i have to say of the sources whence the
 carbon and nitrogen1 indispensable to  
the growth of plants1 are derived4  ,the
 growth of forests1 and the produce of  

meadows1 demonstrate that an            
inexhaustible quantity of carbon is     
furnished for vegetation by the carbonic
 acid of the atmosphere4  ,we obtain    
from an equal surface of forest1 or     
meadow-land1 where the necessary mineral
 elements of the soil are present in a  
suitable state1 and to which no         
carbonaceous matter whatever is         
furnished in manures1 an amount of      
carbon1 in the shape of wood and hay1   
quite equal1 and oftimes more than is   
produced by our fields1 in grain1 roots1
 and straw1 upon which abundance of     
manure has been heaped4  ,it is         
perfectly obvious that the atmosphere   
must furnish to our cultivated fields as
 much carbonic acid1 as it does to an   
equal surface of forest or meadow1 and  
that the carbon of this carbonic acid is
 assimilated1 or may be assimilated by  
the plants growing there1 provided the  
conditions essential to its             
assimilation1 and becoming a constituent
 element of vegetables1 exist in the    

soil of these fields4  ,in many tropical
 countries the produce of the land in   
grain or roots1 during the whole year1  
depends upon one rain in the spring4 ,if
 this rain is deficient in quantity1 or 
altogether wanting1 the expectation of  
an abundant harvest is diminished or    
destroyed4  ,now it cannot be the water 
merely which produces this enlivening   
and fertilising effect observed1 and    
which lasts for weeks and months4 ,the  
plant receives1 by means of this water1 
at the time of its first development1   
the alkalies1 alkaline earths1 and      
phosphates1 necessary to its            
organization4 ,if these elements1 which 
are necessary previous to its           
assimilation of atmospheric nourishment1
 be absent1 its growth is retarded4 ,in 
fact1 the development of a plant is in a
 direct ratio to the amount of the      
matters it takes up from the soil4 ,if1 
therefore1 a soil is deficient in these 
mineral constituents required by plants1
 they will not flourish even with an    

abundant supply of water4  ,the produce 
of carbon on a meadow1 or an equal      
surface of forest land1 is independent  
of a supply of carbonaceous manure1 but 
it depends upon the presence of certain 
elements of the soil which in themselves
 contain no carbon1 together with the   
existence of conditions under which     
their assimilation by plants can be     
effected4 ,we increase the produce of   
our cultivated fields1 in carbon1 by a  
supply of lime1 ashes1 and marl1        
substances which cannot furnish carbon  
to the plants1 and yet it is            
indisputable1--being founded upon       
abundant experience1--that in these     
substances we furnish to the fields     
elements which greatly increase the bulk
 of their produce1 and consequently the 
amount of carbon4  ,if we admit these   
facts to be established1 we can no      
longer doubt that a deficient produce of
 carbon1 or in other words1 the         
barrenness of a field does not depend   
upon carbonic acid1 because we are able 

to increase the produce1 to a certain   
degree1 by a supply of substances which 
do not contain any carbon4 ,the same    
source whence the meadow and the forest 
are furnished with carbon1 is also open 
to our cultivated plants4 ,the great    
object of agriculture1 therefore1 is to 
discover the means best adapted to      
enable these plants to assimilate the   
carbon of the atmosphere which exists in
 it as carbonic acid4 ,in furnishing    
plants1 therefore1 with mineral         
elements1 we give them the power to     
appropriate carbon from a source which  
is inexhaustible2 whilst in the absence 
of these elements the most abundant     
supply of carbonic acid1 or of decaying 
vegetable matter1 would not increase the
 produce of a field4  ,with an adequate 
and equal supply of these essential     
mineral constituents in the soil1 the   
amount of carbonic acid absorbed by a   
plant from the atmosphere in a given    
time is limited by the quantity which is
 brought into contact with its organs of

 absorption4  ,the withdrawal of        
carbonic acid from the atmosphere by the
 vegetable organism takes place chiefly 
through its leaves2 this absorption     
requires the contact of the carbonic    
acid with their surface1 or with the    
part of the plant by which it is        
absorbed4  ,the quantity of carbonic    
acid absorbed in a given time is in     
direct proportion to the surface of the 
leaves and the amount of carbonic acid  
contained in the air2 that is1 two      
plants of the same kind and the same    
extent of surface of absorption1 in     
equal times and under equal conditions1 
absorb one and the same amount of       
carbon4  ,in an atmosphere containing a 
double proportion of carbonic acid1 a   
plant absorbs1 under the same condition1
 twice the quantity of carbon4          
,boussingault observed1 that the leaves 
of the vine1 inclosed in a vessel1      
withdrew all the carbonic acid from a   
current of air which was passed through 
it1 however great its velocity4 7,dumas 

,lecon1 p4#bc47 ,if1 therefore1 we      
supply double the quantity of carbonic  
acid to one plant1 the extent of the    
surface of which is only half that of   
another living in ordinary atmospheric  
air1 the former will obtain and         
appropriate as much carbon as the       
latter4 ,hence results the effects of   
humus1 and all decaying organic         
substances1 upon vegetation4 ,if we     
suppose all the conditions for the      
absorption of carbonic acid present1 a  
young plant will increase in mass1 in a 
limited time1 only in proportion to its 
absorbing surface2 but if we create in  
the soil a new source of carbonic acid1 
by decaying vegetable substances1 and   
the roots absorb in the same time three 
times as much carbonic acid from the    
soil as the leaves derive from the      
atmosphere1 the plant will increase in  
weight fourfold4 ,this fourfold increase
 extends to the leaves1 buds1 stalks1   
c41 and in the increased extent of the  
surface1 the plant acquires an increased

 power of absorbing nourishment from the
 air1 which continues in action far     
beyond the time when its derivation of  
carbonic acid through the roots ceases4 
,humus1 as a source of carbonic acid in 
cultivated lands1 is not only useful as 
a means of increasing the quantity of   
carbon--an effect which in most cases   
may be very indifferent for agricultural
 purposes--but the mass of the plant    
having increased rapidly in a short     
time1 space is obtained for the         
assimilation of the elements of the soil
 necessary for the formation of new     
leaves and branches4  ,water evaporates 
incessantly from the surface of the     
young plant2 its quantity is in direct  
proportion to the temperature and the   
extent of the surface4 ,the numerous    
radical fibrillae replace1 like so many 
pumps1 the evaporated water2 and so long
 as the soil is moist1 or penetrated    
with water1 the indispensable elements  
of the soil1 dissolved in the water1 are
 supplied to the plant4 ,the water      

absorbed by the plant evaporating in an 
aeriform state leaves the saline and    
other mineral constituents within it4   
,the relative proportion of these       
elements taken up by a plant1 is        
greater1 the more extensive the surface 
and more abundant the supply of water2  
where these are limited1 the plant soon 
reaches its full growth1 while if their 
supply is continued1 a greater amount of
 elements necessary to enable it to     
appropriate atmospheric nourishment     
being obtained1 its development proceeds
 much further4 ,the quantity1 or mass of
 seed produced1 will correspond to the  
quantity of mineral constituents present
 in the plant4 ,that plant1 therefore1  
containing the most alkaline phosphates 
and earthy salts will produce more or a 
greater weight of seeds than another    
which1 in an equal time has absorbed    
less of them4 ,we consequently observe1 
in a hot summer1 when a further supply  
of mineral ingredients from the soil    
ceases through want of water1 that the  

height and strength of plants1 as well  
as the development of their seeds1 are  
in direct proportion to its absorption  
of the elementary parts of the soil in  
the preceding epochs of its growth4     
,the fertility of the year depends in   
general upon the temperature1 and the   
moisture or dryness of the spring1 if   
all the conditions necessary to the     
assimilation of the atmospheric         
nourishment be secured to our cultivated
 plants4 ,the action of humus1 then1 as 
we have explained it above1 is chiefly  
of value in gaining time4 ,in           
agriculture1 this must ever be taken    
into account and in this respect humus  
is of importance in favouring the growth
 of vegetables1 cabbages1 c4  ,but the  
cerealia1 and plants grown for their    
roots1 meet on our fields1 in the       
remains of the preceding crop1 with a   
quantity of decaying vegetable          
substances corresponding to their       
contents of mineral nutriment from the  
soil1 and consequently with a quantity  

of carbonic acid adequate to their      
accelerated development in the spring4  
,a further supply of carbonic acid1     
therefore1 would be quite useless1      
without a corresponding increase of     
mineral ingredients4  ,from a morgen of 
good meadow land1 #b1ejj pounds weight  
of hay1 according to the best           
agriculturists1 are obtained on an      
average4 ,this amount is furnished      
without any supply of organic           
substances1 without manure containing   
carbon or nitrogen4 ,by irrigation1 and 
the application of ashes or gypsum1     
double that amount may be grown4 ,but   
assuming #b1ejj pounds weight of hay to 
be the maximum1 we may calculate the    
amount of carbon and nitrogen derived   
from the atmosphere by the plants of    
meadows4  ,according to elementary      
analysis1 hay1 dried at a temperature of
 #ajj deg ,reaumur1 contains #de4h per  
cent4 of carbon1 and #a #a_/b per cent4 
of nitrogen4 #ad per cent4 of water     
retained by the hay1 dried at common    

temperatures1 is driven off at #ajj deg4
 #b1ejj pounds weight of hay1 therefore1
 corresponds to #b1aej pounds1 dried at 
#ajj deg4 ,this shows us1 that #ihd     
pounds of carbon1 and #cb4b pounds      
weight of nitrogen1 have been obtained  
in the produce of one morgen of meadow  
land4 ,supposing that this nitrogen has 
been absorbed by the plants in the form 
of ammonia1 the atmosphere contains     
#ci4a pounds weight of ammonia to every 
#cfdj pounds weight of carbonic acid    
7#ihd carbon1 or #bg per cent471 or in  
other words1 to every #a1jjj pounds     
weight of carbonic acid1 #aj4g pounds of
 ammonia1 that is to about #a_/ajj1jjj1 
the weight of the air1 or #a_/fj1jjj of 
its volume4  ,for every #ajj parts of   
carbonic acid absorbed by the surface of
 the leaves1 the plant receives from the
 atmosphere somewhat more than one part 
of ammonia4  ,with every #a1jjj pounds  
of carbon1 we obtain--    ,from a meadow
 4 #cb #g_/aj pounds of nitrogen4       
,from cultivated fields1    ,in ,wheat  

4 #ba #a_/b     ,oats      4 #bb4c      
,rye       4 #ae4b       ,potatoes  4   
#cd4a       ,beetroot  4 #ci4a          
,clover    4 #dd         ,peas      4   
#fb         ,boussingault obtained from 
his farm at ,bechelbronn1 in ,alsace1 in
 five years1 in the shape of potatoes1  
wheat1 clover1 turnips1 and oats1 #h1chc
 of carbon1 and #bej4g nitrogen4 ,in the
 following five years1 as beetroot1     
wheat1 clover1 turnips1 oats1 and rye1  
#h1aib of carbon1 and #bhd4b of         
nitrogen4 ,in a further course of six   
years1 potatoes1 wheat1 clover1 turnips1
 peas1 and rye1 #aj1idi of carbon1      
#cef4f of nitrogen4 ,in #af years1      
#bg1dbd carbon1 #heh #a_/b nitrogen1    
which gives for every #a1jjj carbon1    
#ca4c nitrogen4  ,from these interesting
 and unquestionable facts1 we may deduce
 some conclusions of the highest        
importance in their application to      
agriculture4  #a4 ,we observe that the  
relative proportions of carbon and      
nitrogen1 stand in a fixed relation to  

the surface of the leaves4 ,those       
plants1 in which all the nitrogen may be
 said to be concentrated in the seeds1  
as the cerealia1 contain on the whole   
less nitrogen than the leguminous       
plants1 peas1 and clover4  #b4 ,the     
produce of nitrogen on a meadow which   
receives no nitrogenised manure1 is     
greater than that of a field of wheat   
which has been manured4  #c4 ,the       
produce of nitrogen in clover and peas1 
which agriculturists will acknowledge   
require no nitrogenised manure1 is far  
greater than that of a potato or turnip 
field1 which is abundantly supplied with
 such manures4  ,lastly4 ,and this is   
the most curious deduction to be derived
 from the above facts1--if we plant     
potatoes1 wheat1 turnips1 peas1 and     
clover1 7plants containing potash1 lime1
 and silex17 upon the same land1 three  
times manured1 we gain in #af years1 for
 a given quantity of carbon1 the same   
proportion of nitrogen which we receive 
from a meadow which has received no     

nitrogenised manure4  ,on a morgen of   
meadow-land1 we obtain in plants1       
containing silex1 lime1 and potash1 #ihd
 carbon1 #cb4b nitrogen4 ,on a morgen of
 cultivated land1 in an average of #af  
years1 in plants containing the same    
mineral elements1 silex1 lime1 and      
potash1 #heg carbon1 #bf4h nitrogen4    
,if we add the carbon and nitrogen of   
the leaves of the beetroot1 and the     
stalk and leaves of the potatoes1 which 
have not been taken into account1 it    
still remains evident that the          
cultivated fields1 notwithstanding the  
supply of carbonaceous and nitrogenised 
manures1 produced no more carbon and    
nitrogen than an equal surface of       
meadow-land supplied only with mineral  
elements4  ,what then is the rationale  
of the effect of manure1--of the solid  
and fluid excrements of animals8  ,this 
question can now be satisfactorily      
answered3 that effect is the restoration
 of the elementary constituents of the  
soil which have been gradually drawn    

from it in the shape of grain and       
cattle4 ,if the land ,i am speaking of  
had not been manured during those #af   
years1 not more than one-half1 or       
perhaps than one-third part of the      
carbon and nitrogen would have been     
produced4 ,we owe it to the animal      
excrements1 that it equalled in         
production the meadow-land1 and this1   
because they restored the mineral       
ingredients of the soil removed by the  
crops4 ,all that the supply of manure   
accomplished1 was to prevent the land   
from becoming poorer in these1 than the 
meadow which produces #b1ejj pounds of  
hay4 ,we withdraw from the meadow in    
this hay as large an amount of mineral  
substances as we do in one harvest of   
grain1 and we know that the fertility of
 the meadow is just as dependent upon   
the restoration of these ingredients to 
its soil1 as the cultivated land is upon
 manures4 ,two meadows of equal surface1
 containing unequal quantities of       
inorganic elements of                   

nourishment1--other conditions being    
equal1--are very unequally fertile2 that
 which possesses most1 furnishes most   
hay4 ,if we do not restore to a meadow  
the withdrawn elements1 its fertility   
decreases4 ,but its fertility remains   
unimpaired1 with a due supply of animal 
excrements1 fluid and solid1 and it not 
only remains the same1 but may be       
increased by a supply of mineral        
substances alone1 such as remain after  
the combustion of ligneous plants and   
other vegetables2 namely1 ashes4 ,ashes 
represent the whole nourishment which   
vegetables receive from the soil4 ,by   
furnishing them in sufficient quantities
 to our meadows1 we give to the plants  
growing on them the power of condensing 
and absorbing carbon and nitrogen by    
their surface4 ,may not the effect of   
the solid and fluid excrements1 which   
are the ashes of plants and grains1     
which have undergone combustion in the  
bodies of animals and of man1 be        
dependent upon the same cause8 ,should  

not the fertility1 resulting from their 
application1 be altogether independent  
of the ammonia they contain8 ,would not 
their effect be precisely the same in   
promoting the fertility of cultivated   
plants1 if we had evaporated the urine1 
and dried and burned the solid          
excrements8 ,surely the cerealia and    
leguminous plants which we cultivate    
must derive their carbon and nitrogen   
from the same source whence the graminea
 and leguminous plants of the meadows   
obtain them6 ,no doubt can be           
entertained of their capability to do   
so4  ,in ,virginia1 upon the lowest     
calculation1 #bb pounds weight of       
nitrogen were taken on the average1     
yearly1 from every morgen of the        
wheat-fields4 ,this would amount1 in    
#ajj years1 to #b1bjj pounds weight4 ,if
 this were derived from the soil1 every 
morgen of it must have contained the    
equivalent of #aaj1jjj pounds weight of 
animal excrements 7assuming the latter1 
when dried1 at the temperature of       

boiling water1 to contain #b per cent474
  ,in ,hungary1 as ,i remarked in a     
former ,letter1 tobacco and wheat have  
been grown upon the same field for      
centuries1 without any supply of        
nitrogenised manure4 ,is it possible    
that the nitrogen essential to1 and     
entering into1 the composition of these 
crops1 could have been drawn from the   
soil8  ,every year renews the foliage   
and fruits of our forests of beech1 oak1
 and chesnuts2 the leaves1 the acorns1  
the chesnuts1 are rich in nitrogen2 so  
are cocoa-nuts1 bread-fruit1 and other  
tropical productions4 ,this nitrogen is 
not supplied by man1 can it indeed be   
derived from any other source than the  
atmosphere8  ,in whatever form the      
nitrogen supplied to plants may be      
contained in the atmosphere1 in whatever
 state it may be when absorbed1 from the
 atmosphere it must have been derived4  
,did not the fields of ,virginia receive
 their nitrogen from the same source as 
wild plants8  ,is the supply of nitrogen

 in the excrements of animals quite a   
matter of indifference1 or do we receive
 back from our fields a quantity of the 
elements of blood corresponding to this 
supply8  ,the researches of             
,boussingault have solved this problem  
in the most satisfactory manner4 ,if1 in
 his grand experiments1 the manure which
 he gave to his fields was in the same  
state1 i4e4 dried at #aaj deg in a      
vacuum1 as it was when analysed1 these  
fields received1 in #af years1 #a1cjj   
pounds of nitrogen4 ,but we know that by
 drying all the nitrogen escapes which  
is contained in solid animal excrements1
 as volatile carbonate of ammonia4 ,in  
this calculation the nitrogen of the    
urine1 which by decomposition is        
converted into carbonate of ammonia1 has
 not been included4 ,if we suppose it   
amounted to half as much as that in the 
dried excrements1 this would make the   
quantity of nitrogen supplied to the    
fields #a1iej pounds4  ,in #af years1   
however1 as we have seen1 only #a1eag   

pounds of nitrogen1 was contained in    
their produce of grain1 straw1 roots1 et
 cetera--that is1 far less than was     
supplied in the manure2 and in the same 
period the same extent of surface of    
good meadow-land 7one hectare  a        
,hessian morgen71 which received no     
nitrogen in manure1 #b1jfb pounds of    
nitrogen4  ,it is well known that in    
,egypt1 from the deficiency of wood1 the
 excrement of animals is dried1 and     
forms the principal fuel1 and that the  
nitrogen from the soot of this excrement
 was1 for many centuries1 imported into 
,europe in the form of sal ammoniac1    
until a method of manufacturing this    
substance was discovered at the end of  
the last century by ,gravenhorst of     
,brunswick4 ,the fields in the delta of 
the ,nile are supplied with no other    
animal manures than the ashes of the    
burnt excrements1 and yet they have been
 proverbially fertile from a period     
earlier than the first dawn of history1 
and that fertility continues to the     

present day as admirable as it was in   
the earliest times4 ,these fields       
receive1 every year1 from the inundation
 of the ,nile1 a new soil1 in its mud   
deposited over their surface1 rich in   
those mineral elements which have been  
withdrawn by the crops of the previous  
harvest4 ,the mud of the ,nile contains 
as little nitrogen as the mud derived   
from the ,alps of ,switzerland1 which   
fertilises our fields after the         
inundations of the ,rhine4 ,if this     
fertilising mud owed this property to   
nitrogenised matters2 what enormous beds
 of animal and vegetable exuviae and    
remains ought to exist in the mountains 
of ,africa1 in heights extending beyond 
the limits of perpetual snow1 where no  
bird1 no animal finds food1 from the    
absence of all vegetation6  ,abundant   
evidence in support of the important    
truth we are discussing1 may be derived 
from other well known facts4 ,thus1 the 
trade of ,holland in cheese may be      
adduced in proof and illustration       

thereof4 ,we know that cheese is derived
 from the plants which serve as food for
 cows4 ,the meadow-lands of ,holland    
derive the nitrogen of cheese from the  
same source as with us2 i4e4 the        
atmosphere4 ,the milch cows of ,holland 
remain day and night on the             
grazing-grounds1 and therefore1 in their
 fluid and solid excrements return      
directly to the soil all the salts and  
earthy elements of their food3 a very   
insignificant quantity only is exported 
in the cheese4 ,the fertility of these  
meadows can1 therefore1 be as little    
impaired as our own fields1 to which we 
restore all the elements of the soil1 as
 manure1 which have been withdrawn in   
the crops4 ,the only difference is1 in  
,holland they remain on the field1      
whilst we collect them at home and carry
 them1 from time to time1 to the fields4
  ,the nitrogen of the fluid and solid  
excrements of cows1 is derived from the 
meadow-plants1 which receive it from the
 atmosphere2 the nitrogen of the cheese 

also must be drawn from the same source4
 ,the meadows of ,holland have1 in the  
lapse of centuries1 produced millions of
 hundredweights of cheese4 ,thousands of
 hundredweights are annually exported1  
and yet the productiveness of the       
meadows is in no way diminished1        
although they never receive more        
nitrogen than they originally contained4
  ,nothing then can be more certain than
 the fact1 that an exportation of       
nitrogenised products does not exhaust  
the fertility of a country2 inasmuch as 
it is not the soil1 but the atmosphere1 
which furnishes its vegetation with     
nitrogen4 ,it follows1 consequently1    
that we cannot increase the fertility of
 our fields by a supply of nitrogenised 
manure1 or by salts of ammonia1 but     
rather that their produce increases or  
diminishes1 in a direct ratio1 with the 
supply of mineral elements capable of   
assimilation4 ,the formation of the     
constituent elements of blood1 that is1 
of the nitrogenised principles in our   

cultivated plants1 depends upon the     
presence of inorganic matters in the    
soil1 without which no nitrogen can be  
assimilated even when there is a most   
abundant supply4 ,the ammonia contained 
in animal excrements exercises a        
favourable effect1 inasmuch as it is    
accompanied by the other substances     
necessary to accomplish its transition  
into the elements of the blood4 ,if we  
supply ammonia associated with all the  
conditions necessary to its             
assimilation1 it ministers to the       
nourishment of the plants2 but if this  
artificial supply is not given they can 
derive all the needed nitrogen from the 
atmosphere--a source1 every loss from   
which is restored by the decomposition  
of the bodies of dead animals and the   
decay of plants4 ,ammonia certainly     
favours1 and accelerates1 the growth of 
plants in all soils1 wherein all the    
conditions of its assimilation are      
united2 but it is altogether without    
effect1 as respects the production of   

the elements of blood where any of these
 conditions are wanting4 ,we can suppose
 that asparagin1 the active constituent 
of asparagus1 the mucilaginous root of  
the marsh-mallow1 the nitrogenised and  
sulphurous ingredients of mustard-seed1 
and of all cruciferous plants1 may      
originate without the aid of the mineral
 elements of the soil4 ,but if the      
principles of those vegetables1 which   
serve as food1 could be generated       
without the co-operation of the mineral 
elements of blood1 without potash1 soda1
 phosphate of soda1 phosphate of lime1  
they would be useless to us and to      
herbivorous animals as food2 they would 
not fulfil the purpose for which the    
wisdom of the ,creator has destined     
them4 ,in the absence of alkalies and   
the phosphates1 no blood1 no milk1 no   
muscular fibre can be formed4 ,without  
phosphate of lime our horses1 sheep and 
cattle1 would be without bones4  ,in the
 urine and in the solid excrements of   
animals we carry ammonia1 and1          

consequently1 nitrogen1 to our          
cultivated plants1 and this nitrogen is 
accompanied by all the mineral elements 
of food exactly in the same proportions1
 in which both are contained in the     
plants which served as food to the      
animals1 or what is the same1 in those  
proportions in which both can serve as  
nourishment to a new generation of      
plants1 to which both are essential4    
,the effect of an artificial supply of  
ammonia1 as a source of nitrogen1 is1   
therefore1 precisely analogous to that  
of humus as a source of carbonic        
acid--it is limited to a gain of time2  
that is1 it accelerates the development 
of plants4 ,this is of great importance1
 and should always be taken into account
 in gardening1 especially in the        
treatment of the kitchen-garden2 and as 
much as possible1 in agriculture on a   
large scale1 where the time occupied in 
the growth of the plants cultivated is  
of importance4  ,when we have exactly   
ascertained the quantity of ashes left  

after the combustion of cultivated      
plants which have grown upon all        
varieties of soil1 and have obtained    
correct analyses of these ashes1 we     
shall learn with certainty which of the 
constituent elements of the plants are  
constant and which are changeable1 and  
we shall arrive at an exact knowledge of
 the sum of all the ingredients we      
withdraw from the soil in the different 
crops4  ,with this knowledge the farmer 
will be able to keep an exact record1 of
 the produce of his fields in harvest1  
like the account-book of a well         
regulated manufactory2 and then by a    
simple calculation he can determine     
precisely the substances he must supply 
to each field1 and the quantity of      
these1 in order to restore their        
fertility4 ,he will be able to express1 
in pounds weight1 how much of this or   
that element he must give in order to   
augment its fertility for any given kind
 of plants4  ,these researches and      
experiments are the great desideratum of

 the present time4 ,,to ,,the ,,united  
,,efforts ,,of ,,the ,,chemists ,,of    
,,all ,,countries ,,we ,,may            
,,confidently ,,look ,,for ,a ,,solution
 ,,of ,,these ,,great ,,questions1 and  
by the aid of ,,enlightened             
,,agriculturists we shall arrive at a   
,,rational system of ,,gardening1       
,,horticulture1 and ,,agriculture1      
applicable to every country and all     
kinds of soil1 and which will be based  
upon the immutable foundation of        
,,observed ,,facts and ,,philosophical  
,,induction4     ,,letter ,,xvi   ,my   
dear ,sir1  ,my recent researches into  
the constituent ingredients of our      
cultivated fields have led me to the    
conclusion that1 of all the elements    
furnished to plants by the soil and     
ministering to their nourishment1 the   
phosphate of lime--or1 rather1 the      
phosphates generally--must be regarded  
as the most important4  ,in order to    
furnish you with a clear idea of the    
importance of the phosphates1 it may be 

sufficient to remind you of the fact1   
that the blood of man and animals1      
besides common salt1 always contains    
alkaline and earthy phosphates4 ,if we  
burn blood and examine the ashes which  
remain1 we find certain parts of them   
soluble in water1 and others insoluble4 
,the soluble parts are1 common salt and 
alkaline phosphates2 the insoluble      
consist of phosphate of lime1 phosphate 
of magnesia1 and oxide of iron4  ,these 
mineral ingredients of the              
blood--without the presence of which in 
the food the formation of blood is      
impossible--both man and animals derive 
either immediately1 or mediately through
 other animals1 from vegetable          
substances used as food2 they had been  
constituents of vegetables1 they had    
been parts of the soil upon which the   
vegetable substances were developed4    
,if we compare the amount of the        
phosphates in different vegetable       
substances with each other1 we discover 
a great variety1 whilst there is        

scarcely any ashes of plants altogether 
devoid of them1 and those parts of      
plants which experience has taught us   
are the most nutritious1 contain the    
largest proportion4 ,to these belong all
 seeds and grain1 especially the        
varieties of bread-corn1 peas1 beans1   
and lentils4  ,it is a most curious fact
 that if we incinerate grain or its     
flour1 peas1 beans1 and lentils1 we     
obtain ashes1 which are distinguished   
from the ashes of all other parts of    
vegetables by the absence of alkaline   
carbonates4 ,the ashes of these seeds   
when recently prepared1 do not          
effervesce with acids2 their soluble    
ingredients consist solely of alkaline  
phosphates1 the insoluble parts of      
phosphate of lime1 phosphate of         
magnesia1 and oxide of iron3            
consequently1 of the very same salts    
which are contained in blood1 and which 
are absolutely indispensable to its     
formation4 ,we are thus brought to the  
further indisputable conclusion that no 

seed suitable to become food for man and
 animals can be formed in any plant     
without the presence and co-operation of
 the phosphates4 ,a field in which      
phosphate of lime1 or the alkaline      
phosphates1 form no part of the soil1 is
 totally incapable of producing grain1  
peas1 or beans4  ,an enormous quantity  
of these substances indispensable to the
 nourishment of plants1 is annually     
withdrawn from the soil and carried into
 great towns1 in the shape of flour1    
cattle1 et cetera4 ,it is certain that  
this incessant removal of the phosphates
 must tend to exhaust the land and      
diminish its capability of producing    
grain4 ,the fields of ,great ,britain   
are in a state of progressive exhaustion
 from this cause1 as is proved by the   
rapid extension of the cultivation of   
turnips and mangel wurzel--plants which 
contain the least amount of the         
phosphates1 and therefore require the   
smallest quantity for their development4
 ,these roots contain #hj to #ib per    

cent4 of water4 ,their great bulk makes 
the amount of produce fallacious1 as    
respects their adaptation to the food of
 animals1 inasmuch as their contents of 
the ingredients of the blood1 i4e4 of   
substances which can be transformed into
 flesh1 stands in a direct ratio to     
their amount of phosphates1 without     
which neither blood nor flesh can be    
formed4  ,our fields will become more   
and more deficient in these essential   
ingredients of food1 in all localities  
where custom and habits do not admit the
 collection of the fluid and solid      
excrements of man1 and their application
 to the purposes of agriculture4 ,in a  
former letter ,i showed you how great a 
waste of phosphates is unavoidable in   
,england1 and referred to the well-known
 fact that the importation of bones     
restored in a most admirable manner the 
fertility of the fields exhausted from  
this cause4 ,in the year #ahbg the      
importation of bones for manure amounted
 to #dj1jjj tons1 and ,huskisson        

estimated their value to be from ,l     
#ajj1jjj to ,l #bjj1jjj sterling4 ,the  
importation is still greater at present1
 but it is far from being sufficient to 
supply the waste4  ,another proof of the
 efficacy of the phosphates in restoring
 fertility to exhausted land is afforded
 by the use of the guano--a manure      
which1 although of recent introduction  
into ,england1 has found such general   
and extensive application4  ,we believe 
that the importation of one             
hundred-weight of guano is equivalent to
 the importation of eight hundred-weight
 of wheat--the hundred-weight of guano  
assumes in a time which can be          
accurately estimated the form of a      
quantity of food corresponding to eight 
hundred-weight of wheat4 ,the same      
estimate is applicable in the valuation 
of bones4  ,if it were possible to      
restore to the soil of ,england and     
,scotland the phosphates which during   
the last fifty years have been carried  
to the sea by the ,thames and the       

,clyde1 it would be equivalent to       
manuring with millions of               
hundred-weights of bones1 and the       
produce of the land would increase      
one-third1 or perhaps double itself1 in 
five to ten years4  ,we cannot doubt    
that the same result would follow if the
 price of the guano admitted the        
application of a quantity to the surface
 of the fields1 containing as much of   
the phosphates as have been withdrawn   
from them in the same period4  ,if a    
rich and cheap source of phosphate of   
lime and the alkaline phosphates were   
open to ,england1 there can be no       
question that the importation of foreign
 corn might be altogether dispensed with
 after a short time4 ,for these         
materials ,england is at present        
dependent upon foreign countries1 and   
the high price of guano and of bones    
prevents their general application1 and 
in sufficient quantity4 ,every year the 
trade in these substances must decrease1
 or their price will rise as the demand 

for them increases4  ,according to these
 premises1 it cannot be disputed1 that  
the annual expense of ,great ,britain   
for the importation of bones and guano  
is equivalent to a duty on corn3 with   
this difference only1 that the amount is
 paid to foreigners in money4  ,to      
restore the disturbed equilibrium of    
constitution of the soil1--to fertilise 
her fields1--,england requires an       
enormous supply of animal excrements1   
and it must1 therefore1 excite          
considerable interest to learn1 that she
 possesses beneath her soil beds of     
fossil guano1 strata of animal          
excrements1 in a state which will       
probably allow of their being employed  
as a manure at a very small expense4    
,the coprolithes discovered by ,dr4     
,buckland1 7a discovery of the highest  
interest to ,geology17 are these        
excrements2 and it seems extremely      
probable that in these strata ,england  
possesses the means of supplying the    
place of recent bones1 and therefore the

 principal conditions of improving      
agriculture--of restoring and exalting  
the fertility of her fields4  ,in the   
autumn of #ahdb1 ,dr4 ,buckland pointed 
out to me a bed of coprolithes in the   
neighbourhood of ,clifton1 from half to 
one foot thick1 inclosed in a limestone 
formation1 extending as a brown stripe  
in the rocks1 for miles along the banks 
of the ,severn4 ,the limestone marl of  
,lyme ,regis consists1 for the most     
part1 of one-fourth part of fossil      
excrements and bones4 ,the same are     
abundant in the lias of ,bath1 ,eastern 
and ,broadway ,hill1 near ,evesham4 ,dr4
 ,buckland mentions beds1 several miles 
in extent1 the substance of which       
consists1 in many places1 of a fourth   
part of coprolithes4  ,pieces of the    
limestone rock in ,clifton1 near        
,bristol1 which is rich in coprolithes  
and organic remains1 fragments of bones1
 teeth1 c41 were subjected to analysis1 
and were found to contain above #ah per 
cent4 of phosphate of lime4 ,if this    

limestone is burned and brought in that 
state to the fields1 it must be a       
perfect substitute for bones1 the       
efficacy of which as a manure does not  
depend1 as has been generally1 but      
erroneously supposed1 upon the          
nitrogenised matter which they contain1 
but on their phosphate of lime4  ,the   
osseous breccia found in many parts of  
,england deserves especial attention1 as
 it is highly probable that in a short  
time it will become an important article
 of commerce4  ,what a curious and      
interesting subject for contemplation6  
,in the remains of an extinct animal    
world1 ,england is to find the means of 
increasing her wealth in agricultural   
produce1 as she has already found the   
great support of her manufacturing      
industry in fossil fuel1--the preserved 
matter of primeval forests1--the remains
 of a vegetable world4 ,may this        
expectation be realised6 and may her    
excellent population be thus redeemed   
from poverty and misery6