material from the ,google ,print        
project47          ,transcriber's ,note3
 ,a few typographical errors have been  
corrected4 ,details are given at the end
 of the text4     ,,heads ,,of          
,,lectures  ,,on ,a ,,course ,,of       
,,experimental ,,philosophy1            
,,particularly ,,including  ,,chemistry1
  ,,delivered ,,at ,,the ,,new ,,college
 ,,in ,,hackney4  ,by ,,joseph          
,,priestley1 ,,ll4,d4 ,f4,r4,s4  ,,ac4  
,,imp4 ,,petrop4 ,r4 ,,paris4 ,,holm4   
,,taurin4 ,,aurel4 ,,med4 ,,paris4      
,,harlem4 ,,cantab4 ,,americ4 ,,et      
,,philad4 ,,soc4  ,,qui ,,docet         
,,discit4--,,wm4 ,,lilly  ,,london3     
,,printed ,,for ,j4 ,,johnson1 ,,no4    
#gb1 ,,st4 ,,paul',s ,,church-,,yard4   
#agid4     ,,the ,,preface4   ,situated1
 as ,i happily am1 in the neighbourhood 
of the ,new ,college at ,hackney1 an    
institution that does honour to the     
,dissenters1 an institution open to all 
persons without distinction#a1 and      
connected as ,i am by friendship with   

the tutors1 ,i was glad to give it every
 assistance in my power2 and therefore  
undertook to read the ,lectures on      
,history and ,general ,policy which ,i  
had composed when ,i was tutor at       
,warrington1 and also to give another   
course on the subject of ,experimental  
,philosophy4 ,with this view ,i drew up 
the following ,heads of ,lectures2 and1 
to save the students the trouble of     
transcribing them1 they are now printed4
 ,to other persons they may serve as a  
compendious view of the most important  
discoveries relating to the subject4    
,footnote #a3 ,one gentleman of the     
,roman ,catholic persuasion1 and        
several of the ,church of ,england1 are 
now in the ,college4  ,as it was found  
most convenient1 with respect to the    
other business of the college1 to       
confine this course to one lecture in a 
week1 ,i contrived to bring within that 
compass as much of the subject of       
experimental philosophy as ,i well      
could1 and especially to include the    

whole of what is called chemistry1 to   
which so much attention is now given1   
and which presents so many new fields of
 philosophical investigation4  ,besides 
that the plan of the young gentlemen's  
studies would not admit of it1 ,i think 
it most advisable not to trouble        
beginners with more than a large outline
 of any branch of science4 ,by this     
means they are not fatigued by too long 
an attention to any one subject1 a      
greater variety of articles may be      
brought before them1 and in future life 
they may pursue any of them as much     
farther as their inclination may        
dispose1 and their ability and          
opportunity shall enable1 them to do it4
  ,i do not give any account of the     
experiments introduced into the several 
lectures4 ,they will be sufficiently    
indicated by the subjects of them4 ,they
 were as many as ,i could conveniently  
make within the time2 and where the     
experiments themselves could not be     
made1 ,i usually exhibited both the     

different substances employed in them1  
and those that were the result of them4 
,as these lectures were calculated for  
the use of the students at the ,new     
,college1 ,i prefix an ,address to them1
 the same in substance with that which  
,i delivered to them at the close of the
 session of #agia4 ,in it may be seen a 
specimen of the language we hold to them
 on the subject of politics1 which with 
reasonable men will serve as an answer  
to the many calumnies that have been    
thrown out against us1 as disaffected to
 the government of this country4  ,such 
institutions will1 indeed1 always be    
objects of hatred and dread to bigots   
and the advocates for arbitrary power1  
but the pride of a truly free country4  
,i therefore conclude with my earnest   
prayer 7the accomplishment of which the 
present state of the ,college does not  
allow us to doubt7 ,,esto ,,perpetua4   
,,the ,,dedication4  ,,to ,,the         
,,students ,,at ,,the ,,new ,,college   
,,in ,,hackney4   ,my young ,friends1   

,having drawn up the following ,heads of
 ,lectures for your use1 ,i take the    
liberty thus publickly to dedicate them 
to you2 and as ,i earnestly wish for    
your improvement and happiness in all   
respects1 excuse me if ,i take the      
farther liberty of making a few         
observations1 and giving you some       
advice1 of a more general nature1       
adapted to your age and circumstances4  
,as you will soon leave this place of   
education1 and enter upon your several  
professions and employments1 ,i hope    
your conduct will demonstrate to the    
world the solid advantages of this      
institution1 and that the great expence 
attending it1 and the best attention of 
the managers1 have not been bestowed in 
vain4  ,many liberal friends of science1
 of virtue1 and of religion1 have       
contributed to procure you the          
advantages which you enjoy4 ,they have  
spared no pains to provide able and     
careful tutors1 and you have had every  
other advantage for the prosecution of  

your studies that they could procure    
you1 unclogged by any subscription to   
articles of faith1 or obligation of any 
other kind1 besides such as they have   
deemed necessary for your own good1 and 
to give the institution its greatest    
effect4 ,this is an advantage you could 
not have found elsewhere1 at least in   
this country4 ,and in every seminary of 
education much more depends upon        
opportunity for study1 free from any    
obstruction1 and undue bias1 than upon  
the ability of tutors2 though there is  
an additional advantage when they are   
able men1 and eminent in the branches of
 science which they undertake to teach4 
,but this is by no means so essential as
 many other circumstances4  ,whatever be
 the qualifications of your tutors1 your
 improvement must chiefly depend upon   
yourselves4 ,they cannot think or labour
 for you4 ,they can only put you in the 
best way of thinking and labouring for  
yourselves4 ,if1 therefore1 you get     
knowledge1 you must acquire it by your  

own industry4 ,you must form all        
conclusions1 and all maxims1 for        
yourselves1 from premises and data      
collected1 and considered by yourselves4
 ,and it is the great object of this    
institution to remove every bias the    
mind can lie under1 and give the        
greatest scope to true freedom of       
thinking and inquiry4 ,and provided you 
be intelligent and virtuous men1 and    
good citizens1 it will be no cause of   
regret to the friends of this           
institution1 if1 with respect to        
religion1 or politics1 you adopt systems
 of principles1 and maxims of conduct1  
very different from theirs4  ,give me   
leave1 now that ,i am addressing you as 
young men1 and young students1 to       
suggest a caution on a subject1 of the  
importance of which it is hardly        
possible that you should be sufficiently
 aware1 because it is only impressed by 
that experience which you have not yet  
had4 ,i mean that degree of vanity which
 generally accompanies the acquirements 

that diligent persons of your age make  
in places of liberal education1 and the 
contempt they are too apt to entertain  
for those who have not made the same    
proficiency with themselves4 ,and ,i    
assure you1 that in the observations ,i 
shall make on this subject1 ,i have no  
view whatever to any thing that ,i have 
observed1 or heard1 of any of you in    
particular4 ,but ,i have been in your   
situation myself1 and ,i know the       
importance of these observations to     
students in general4  ,you are now at an
 age in which young persons usually make
 the most sensible advances in          
knowledge1 and in which the             
understanding appears to ripen the most 
rapid manner4 ,you are able to say every
 year1 every month1 and almost every    
day1 what particular advances you have  
made1 and how much you know more than   
you did before4 ,and being taught1 and  
accustomed1 to express your thoughts in 
writing1 you find yourselves qualified  
to do this in a manner of which you had 

no idea1 or expectation1 but a little   
time ago4 ,you also perfectly remember  
what you have so recently learned1 and  
many respects may be more particular and
 exact than even your tutors themselves4
  ,the almost unavoidable effect of this
 is a high idea of your own powers and  
attainments1 and too often a            
proportionable contempt of those who1   
not having had equal advantages1 cannot 
do what you are easily capable of4 ,a   
certain degree of vanity is1 therefore1 
excusable in young persons2 and1 indeed1
 it is by means of it that they are     
excited to exert themselves in a manner 
that they would not otherwise have done4
 ,but be careful that this temper be not
 indulged to excess1 for it will then be
 found to have serious ill consequences2
 the least of which is the precluding   
future improvement1 from being already  
satisfied with yourselves1 and conscious
 of a sufficient superiority over       
others4  ,the foundation of this        
self-conceit1 on account of literary    

attainments1 will be found to be        
extremely weak4 ,in fact1 we learn more 
before the period to which you are now  
arrived1 and ,i hope you will continue  
to learn more after it1 without its     
being so much noticed2 and the ability  
that is discovered in the acquirements  
which are the subjects of this vanity is
 not greater than appears on other      
occasions4 ,only they are not so        
conspicuous4  ,what we all learn in the 
first three years of our lives1 is much 
more extraordinary in its nature than   
all that we acquire afterwards4 ,i mean 
the perfect use of our limbs1 and the   
elements of speech4 ,what we learn in a 
month in that early period of life1     
could not1 if we were brought up in the 
ignorance of it1 be learned in a year at
 any subsequent period4 ,but these      
acquirements being universal1 and what  
the circumstances in which we are all   
necessarily in compel us to learn1 it   
does not appear extraordinary in any    
particular individual4 ,also1 the       

proficiency that boys make at a grammar 
school1 in which1 in general1 the dead  
languages only are taught 7a knowledge  
of which is commonly the result of      
severe application7 is too common to be 
the cause of much self-conceit4 ,but the
 advances that are made at places of    
liberal education are both less common1 
and of a more conspicuous nature4  ,you 
will also find1 if you continue your    
application to study1 that it is only   
the elements of science that you can    
acquire here1 and that if you live many 
years1 they will bear but a small       
proportion to your future acquirements4 
,but those future acquirements1 in      
consequence of their bearing a less     
proportion to your whole stock of       
knowledge1 will not be so conspicuous4  
,thus1 though all the buildings that in 
one year are added to such a city as    
,london would make a pretty large       
country town1 they bear so small a      
proportion to what was built before1    
that they are not much noticed2 whereas1

 had half the quantity of building been 
erected in a place where no house had   
existed before1 it would have been a    
memorable event in the history of the   
country4  ,also1 as in old cities many  
buildings will fall to decay1 while new 
ones are added2 you must expect to      
forget much of what you now know4 ,no   
man can give equal attention to every   
object2 and as we advance in life1 we1  
in general1 only learn new things at the
 expence of the old ones4 ,but then they
 are the more valuable articles of      
knowledge1 the more general and leading 
principles1 which remain with us2 while 
the more useless ones1 things to which  
we give less attention because we find  
them to be of less use1 disappear4 ,yet 
it is no uncommon thing for ingenious   
students to despise old scholars who are
 not so ready in the minutiae of        
literature1 though they may have        
forgotten more than those youths ever   
knew1 and may retain what they cannot   
acquire without forgetting as much4     

,another observation proper to lessen   
the conceit of literary men1 is1 that   
genius is not confined to them1 but is  
equally great1 though not equally       
conspicuous1 in every other line of     
life1 and especially in manufactures and
 the arts4 ,here1 however1 discoveries  
equal1 with respect to sagacity1 to     
those of ,newton1 contribute little to  
posthumous fame1 because the discoverers
 are not writers4  ,but the greatest    
branch of intellectual excellence with  
respect to which every other is nothing1
 and which1 from its nature1 can never  
be foundation of any self-conceit1 is   
virtue1 or right dispositions of mind1  
leading to right conduct in life4       
,proper sentiments1 and just affections 
of mind1 arise from just1 and often     
comprehensive1 views of things1 past1   
present1 and to come4 ,and if the real  
greatness of any thought1 or action1 be 
estimated by the number of elements that
 constitute it1 and its remoteness from 
the dictates of sense and natural       

appetite1 a virtuous and pious man will 
appear to be a much more dignified      
character1 more proper to be viewed with
 admiration and esteem1 than the        
greatest scholar2 discovering1 in fact1 
greater comprehension and force of mind4
 ,i mean1 however1 that virtue which is 
the result of reflection1 of discipline1
 and much voluntary exertion1 which1    
though operating with equal promptness  
and facility1 is as much superior to    
mere innocence1 and what is commonly    
called good nature1 as motions          
secondarily automative are to those that
 are primarily so2 a comparison which   
you who have studied ,hartley's ,theory 
of the ,mind will see the force of4     
,these considerations ,i take the       
liberty to suggest1 as being proper to  
lessen that vanity which is so incident 
to those who distinguish themselves in  
the fields of literature1 and which1    
operating like the acquisition of       
riches1 or power1 or any possession that
 is rare among men1 instead of          

enlarging1 may tend to contract the     
mind1 by confining its attention to     
itself4 ,beginning with a generous      
emulation1 it proceeds to envy and      
jealousy1 and ends in actual hatred and 
malignity1 against which you cannot1    
surely1 be too strongly put upon your   
guard2 this being the greatest depravity
 to which human nature is subject1 and  
which yet1 like any other vice1 may be  
in full possession of the mind1 without 
the person himself knowing1 or          
suspecting it2 unless he give more      
attention to his feelings than most     
persons do4 ,if no man ever thought     
himself to be avaricious1 or cruel1 can 
it be expected that any person should   
ever discover that he is too            
self-conceited8  ,better1 however1      
infinitely better1 were it to rank with 
the merest dunces1 than have the conceit
 and malignity 7produced originally from
 conceit7 of some who have distinguished
 themselves the most as linguists1      
critics1 and poets4 ,even the study of  

nature1 though1 from its vast extent1 it
 is less apt to produce this baneful    
effect1 is not always a sufficient guard
 against it4 ,this is an affecting and  
an alarming consideration4 ,but in the  
intellectual1 as in the civil and       
commercial world1 we gain nothing but at
 the risk of some loss2 and in this case
 the possible gain is worth the risk of 
even this great loss4  ,for when        
literary1 and scientific excellence     
coincide with that which is of a moral  
nature1 it adds unspeakably to the value
 of a character4 ,ingenuity coupled with
 modesty1 and great genius with         
benevolence and true piety1 constitute  
the perfection of human character1 and  
is what we should ever have in view4    
,and a course of education in which both
 these objects are equally attended to1 
is the only one that deserves to be     
called liberal3 but such as1 ,i hope1   
you have found this to be4  ,give me    
leave further to observe to you1 that   
the time that you spend in a place of   

liberal education is of more importance 
to you than you can be at present aware 
of4 ,whatever be the sphere of life for 
which you are destined1 the probability 
is1 that you will hereafter have but    
little leisure for reading and studying1
 compared to what you have now4         
,besides1 general maxims of all kinds1  
such as are the foundation of all our   
future conduct1 in morals1 religion1 or 
politics1 are generally formed at your  
time of life4 ,from this period expect  
no great change in your opinions1 or    
conduct2 because now it is that you give
 particular attention to the forming    
your opinions on all subjects of        
importance2 so that very little that is 
materially new to you can be expected to
 occur to you in future life1 and almost
 every thing that you would choose to   
read will only tend to confirm you in   
the general principles that you will now
 adopt4 ,there are1 no doubt1 exceptions
 to this1 as well as every other general
 observation2 but it is wisdom to       

suppose1 and to act upon the            
supposition1 that we are constituted as 
the generality of mankind are1 and that 
we shall feel1 and act1 as they do4     
,since1 then1 so much depends on the    
leading principles and maxims which you 
will now adopt1 be it your care to form 
just and good ones1 and let no authority
 of tutors1 or others1 have any undue   
influence over you4 ,in all cases think 
and judge for yourselves1 and especially
 on all subjects of importance1 and with
 as much attention as you can give to   
them4  ,it may not be amiss1 in the     
present state of things1 to say         
something respecting another subject1   
which now commands universal attention4 
,you cannot but be apprised1 that many  
persons entertain a prejudice against   
this ,college1 on account of the        
republican1 and1 as they choose to call 
them1 the licentious1 principles of     
government1 which are supposed to be    
taught here4 ,show1 then1 by your       
general conversation1 and conduct1 that 

you are the friends of peace and good   
order2 and that1 whatever may be your   
opinions with respect to the best form  
of government for people who have no    
previous prejudices or habits1 you will 
do every thing in your power for the    
preservation of that form of it which   
the generality of your countrymen       
approve1 and under which you live1 which
 is all that can be reasonably expected 
of any subject4 ,as it is not necessary 
that every good son should think his    
parent the wisest and best man in the   
world1 but it is thought sufficient if  
the son pay due respect and obedience to
 his parent2 so neither is it to be     
expected that every man should be of    
opinion that the form of government     
under which he happens to be born is the
 best of all possible forms of          
government4 ,it is enough that he submit
 to it1 and that he make no attempt to  
bring about any change1 except by fair  
reasoning1 and endeavouring to convince 
his countrymen1 that it is in their     

power to better their condition in that 
respect1 as well as in any other4       
,think1 therefore1 speak1 and write1    
with the greatest freedom on the subject
 of government1 particular or general1  
as well as on any other that may come   
before you4 ,it can only be avowed      
tyranny that would prevent this4 ,but at
 the same time submit yourselves1 and   
promote submission in others1 to that   
form of government which you find to be 
most approved1 in this country1 which at
 present unquestionably is that by      
,king1 ,lords1 and ,commons4  ,as to    
religion1 we may1 surely1 be allowed to 
think and act entirely for ourselves2 in
 all cases obeying ,god and conscience  
rather than man4 ,but let us be thankful
 for the degree of liberty that we are  
allowed1 though it be not all that we   
are justly entitled to2 and let us not  
use any other means than reason and     
argument in order to better our         
condition4 ,by this peaceable and steady
 conduct we shall at length convince    

those who will hear reason1 that we are 
entitled to greater consideration2 and  
doubt not but whatever is true and      
right1 will finally prevail1 and be     
universally established4  ,that any of  
your tutors1 or any of the friends of   
this institution1 wish to promote       
reformation1 in church or state1 by any 
other means than those of reason1 and   
argument1 is a calumny1 utterly void of 
foundation1 or probability4 ,but your   
conduct1 dispersed as you will soon be  
in different parts of the country1 will 
be the best means of refuting it4 ,let  
us leave the method of proceeding by    
riot and tumult to those persons to     
whose schemes such proceedings are      
congenial4 ,truth stands in no need of  
such support1 and will always triumph   
when assailed by such weapons4 ,in      
return1 then1 for the advantages which  
you have enjoyed in this institution1 do
 it this service2 and in recommending   
it1 ,i trust you are doing substantial  
service to the cause of liberty and     

truth2 and conferring a most important  
benefit on your country1 and on mankind4
     ,,contents4   ,,lecture ,i4 ,the   
,introduction                           
#a  ,,lecture ,,ii4 ,of the ,properties 
of all ,matter                          
#i ,of ,aeriform ,substances            
#ac  ,,lecture ,,iii4 ,of ,atmospherical
 ,air                                   
#ae  ,,lecture ,,iv4 ,of                
,dephlogisticated ,air                  
#ah ,of ,phlogisticated ,air            
#bj  ,,lecture ,v4 ,of ,inflammable ,air
                                        
#ba  ,,lecture ,,vi4 ,of ,nitrous ,air  
#bc  ,,lecture ,,vii4 ,of ,fixed ,air   
#bg ,of ,hepatic ,air                   
#bi ,of ,phosphoric ,air                
#cj  ,,lecture ,,viii4 ,of              
,dephlogisticated ,marine ,acid ,air    
#ca ,of ,phlogisticated ,marine ,acid   
,air                            #cb     
,,lecture ,,ix4 ,of ,vitriolic ,acid    
,air                                    
#cd ,of ,fluor ,acid ,air               

#cf  ,,lecture ,x4 ,of ,alkaline ,air   
#cg ,miscellaneous ,observations        
relating to ,air                   #ch  
,,lecture ,,xi4 ,of ,liquid ,substances2
 and first of ,water                    
#da  ,,lecture ,,xii4 ,of the ,nitrous  
,acid                                   
#de  ,,lecture ,,xiii4 ,of the          
,vitriolic ,acid                        
#di ,of the ,marine ,acid               
#eb  ,,lecture ,,xiv4 ,of the ,vegetable
 ,acids1 and others of a less perfect   
nature  #ed  ,,lecture ,,xv4 ,of the    
,phosphoric ,acid                       
#ei  ,,lecture ,,xvi4 ,of ,alkalis      
#fb  ,,lecture ,,xvii4 ,of ,liquid      
,inflammable ,substances                
#ff ,of ,a,ether                        
#fh  ,,lecture ,,xviii4 ,of ,oil        
#gj  ,,lecture ,,xix4 ,of ,solid        
,substances                             
#gf ,of ,calcareous ,earth              
#gg ,of ,siliceous ,earth               
#gi  ,,lecture ,,xx4 ,of ,argillaceous  
,earth                                  

#ha ,of ,terra ,ponderosa               
#hb ,of ,magnesia                       
#hc  ,,lecture ,,xxi4 ,of ,ores         
#hd ,of ,gold                           
#hg  ,,lecture ,,xxii4 ,of ,silver      
#ij ,of ,platina                        
#ib  ,,lecture ,,xxiii4 ,of ,mercury    
#id  ,,lecture ,,xxiv4 ,of ,lead        
#ii ,of ,copper                         
#aja  ,,lecture ,,xxv4 ,of ,iron        
#aje  ,,lecture ,,xxvi4 ,of ,tin        
#aji ,of the ,semi-metals               
#aac  ,,lecture ,,xxvii4 ,of ,nickel    
#aae ,of ,arsenic                       
#aaf ,of ,cobalt                        
#aah ,of ,zinc                          
#aai  ,,lecture ,,xxviii4 ,of ,antimony 
#aba ,of ,manganese                     
#abc ,of ,wolfram                       
#abd ,of ,molybdena                     
#abe ,of ,solid ,combustible ,substances
                             #abf       
,,lecture ,,xxix4 ,of the ,doctrine of  
,phlogiston and the ,composition of     
,water  #abg  ,,lecture ,,xxx4 ,of ,heat

                                        
#ace  ,,lecture ,,xxxi4 ,of ,animal     
,heat                                   
#ade  ,,lecture ,,xxxii4 ,of ,light     
#adh  ,,lecture ,,xxxiii4 ,of ,magnetism
                                        
#aee  ,,lecture ,,xxxiv4 ,of            
,electricity                            
#afb  ,,lecture ,,xxxv4 ,the same       
,subject continued                      
#agj  ,,lecture ,,xxxvi4 ,the same      
,subject continued                      
#agg     ,,lectures ,,on ,,experimental 
,,philosophy4     ,,lecture ,i4   ,the  
,introduction4  ,the object of          
experimental philosophy is the knowledge
 of nature in general1 or more strictly1
 that of the properties of natural      
substances1 and of the changes of those 
properties in different circumstances4  
,this knowledge can only be attained by 
experiment1 or observation2 as that clay
 is capable of becoming hard by means of
 fire1 and thereby being made into      
bricks1 and that by the same means      

lime-stone can be converted into        
quick-lime1 and by the addition of water
 and sand1 make mortar4 ,it is by       
observation also that we discover that  
stones and other heavy bodies fall to   
the ground1 and that a magnet will      
attract iron4 ,in other words1          
experimental philosophy is an           
investigation of the wisdom of ,god in  
the works and the laws of nature1 so    
that it is one of the greatest objects  
to the mind of man1 and opens a field of
 inquiry which has no bounds2 every     
advance we make suggesting new doubts   
and subjects of farther inquiry4  ,the  
uniformity we discover in the properties
 of natural substances enables us to lay
 down general rules1 or principles1     
which1 being invariable1 we call the    
laws of nature2 and by our knowledge of 
these laws we are able to predict1 and  
at our own pleasure to produce1         
particular results1 and this is the     
source of all the powers of man4 ,it is 
the direction we acquire of the powers  

of nature2 so that1 as ,lord ,bacon     
observed1 knowledge is power4  ,all arts
 and manufactures are derived from      
science4 ,thus the doctrine of mechanics
 is an application of the law of        
gravitation4 ,every thing we are capable
 of doing by means of the steam-engine  
is derived from our knowledge of the    
properties of water in steam2 all the   
great effects of gunpowder we owe to our
 knowledge of the composition1 and      
chemical properties1 of that substance4 
,every new appearance in nature is      
preceded by some new circumstance1 and  
to this1 or rather to something always  
attending it1 we say that the appearance
 is owing4 ,this circumstance we        
therefore call the cause1 and the new   
appearance the effect of that cause4    
,thus we say that the union of          
phlogiston to a particular kind of earth
 is the cause of its becoming a metal4  
,it is one of the principal rules of    
philosophizing to admit no more causes  
than are necessary to account for the   

effects4 ,thus1 if the power of gravity1
 by which heavy bodies fall to the      
earth1 be sufficient to retain the      
planets in their orbits1 we are         
authorized to reject the ,cartesian     
,vortices4 ,in other words1 we must make
 no more general propositions than are  
necessary to comprehend all the         
particulars contained in them4 ,thus1   
after having observed that iron consists
 of a particular kind of earth united to
 phlogiston1 and that it is soluble in  
acids2 and that the same is true of all 
other metallic substances1 we say1      
universally1 that all metals consist of 
a peculiar earth and phlogiston1 and    
that they are all soluble in some acid4 
,of the circumstances which occasion a  
change in the properties of bodies1 some
 are the addition of what are properly  
called substances1 or things that are   
the objects of our senses1 being        
visible1 tangible1 or having weight1 c4 
,thus the addition of an acid changes an
 alkali into a neutral salt4 ,but other 

changes are occasioned either by a      
change of texture in the substance      
itself1 or the addition of something    
that is not the object of any of our    
senses4 ,thus1 a piece of steel becomes 
a magnet by the touch of another magnet1
 and a drop of glass acquires the       
property of flying asunder by a small   
fracture1 in consequence of falling when
 red hot into cold water4 ,such also1 in
 the opinion of some1 is the difference 
between hot and cold substances4  ,till 
the nature of the cause be ascertained1 
it is convenient to make use of the term
 principle1 as including both of the    
above-mentioned causes of the change of 
properties in bodies4 ,thus1 whatever be
 the real cause of gravity1 or of       
inflammability1 we may speak of the     
principle of gravity1 or of             
inflammability2 whether1 with ,newton1  
we suppose gravity to be occasioned by a
 fluid pervading the whole universe1    
which he termed aether1 and whether     
inflammability be caused by the presence

 of a real substance called phlogiston1 
or not4 ,in this manner we use the      
letters x and y to denote unknown       
quantities in algebra4  ,when changes   
are made in substances by the addition  
of other substances1 they make what is  
called a chemical union2 and in this    
case the properties of the compound     
cannot with any certainty be deduced    
from those of the component parts1 but  
must be ascertained by fresh            
experiments4 ,thus1 from the specific   
gravities1 or the degrees of fusibility1
 of two metals1 those of the compound   
cannot be predicted4 ,neither water nor 
acid of vitriol will separately dissolve
 iron1 so as to produce inflammable air1
 but both together will do it4 ,however1
 the properties of similar compounds are
 similar to one another4 ,thus1 all     
metals dissolved in acids are           
precipitated by mild alkalis4 ,this     
chemical union of two substances we     
ascribe to a certain elective           
attraction1 or affinity that subsists   

between them1 in consequence of which   
they unite with one another whenever a  
proper opportunity offers1 in preference
 to those substances to which they were 
before united4 ,thus the vitriolic acid1
 having a stronger affinity with the    
vegetable alkali which is the basis of  
nitre1 will unite with that alkali1 and 
with it form another compound1 called   
vitriolated tartar1 while the acid of   
nitre1 being detached from its base1 is 
collected separately4  ,when two        
substances compose one liquid1 and a    
third1 which has a stronger affinity    
with either of the two parts than they  
have with each other1 is added to them1 
it will unite with that part1 and take  
its place in the solution1 while the    
other will in many cases be             
precipitated1 and may be collected4     
,thus the earth of alum is precipitated 
from a solution of alum by salt of      
tartar4 ,this is the case of simple     
affinity4  ,when both the substances are
 compounds1 the component parts of which

 have a weaker affinity with each other 
than they have with those of the other  
compound1 two new combinations are      
formed1 and this is called a case of    
double affinity4 ,thus when             
phlogisticated alkali is poured into a  
solution of green vitriol1 the acid of  
the vitriol unites with the alkali1     
while the phlogiston joining the calx of
 iron makes ,prussian blue4  ,all nature
 lying open to our investigation1 we    
must consider the different parts in    
some order4 ,but it is not very material
 which we adopt1 because1 begin where we
 will1 the properties of the substances 
we first treat of will be connected with
 those which must be particularly       
considered afterwards1 the changes in   
one substance being occasioned by its   
union with another4 ,it will be         
impossible1 for example1 to explain the 
properties of metals without considering
 the acids1 because by their union with 
acids very important changes are made in
 their properties4  ,there have been    

three principal methods of arranging    
natural substances4 ,one is according to
 the three kingdoms1 as they are called1
 into which they have been distributed1 
viz4 the mineral1 the vegetable1 and the
 animal4 ,another is according to the   
elements which enter into their         
composition1 and a third according to   
the form in which they are usually      
found1 viz4 aerial1 fluid1 or solid4    
,upon the whole this last appears to me 
to be the most convenient1 especially as
 it is easy to intermix general         
observations concerning the other       
divisions when they are particularly    
wanted4 ,as there will be frequent      
occasion to speak of the component and  
elementary parts of all substances1 ,i  
shall here observe1 that1 according to  
the latest observations1 the following  
appear to be the elements which compose 
all natural substances1 viz4            
dephlogisticated air1 or the acidifying 
principle2 phlogiston1 or the alkaline  
principle2 the different earths1 and the

 principles of heat1 light1 and         
electricity4 ,besides these1 there are  
the following principles which have not 
been proved to be substances1 viz4      
attraction1 repulsion1 and magnetism4   
,by the help of these principles we are 
able1 according to the present state of 
natural knowledge1 to explain all the   
appearances that have yet occurred to   
us4     ,,lecture ,,ii4   ,of the       
,properties of all ,matter4  ,before ,i 
consider the properties of particular   
substances1 it will be proper to mention
 those which are common to them all4    
,but ,i shall first observe1 that the   
term substance has no proper idea       
annexed to it1 but is merely a          
convenience in speech2 since we cannot  
speak of the properties of substances1  
such as hard1 round1 coloured1 c4 c4    
7which circumstances alone affect our   
senses1 and thereby give proper ideas7  
without saying that they inhere in1 or  
belong to1 some thing1 substance1 or    
substratum4 ,the terms being and person 

are also in the same predicament4  ,one 
property of all substances is extension1
 since they all occupy some portion of  
space4  ,the incapacity of any substance
 to change its place has been termed1   
though improperly1 the vis inertiae of  
matter4 ,it is sufficient to say1 that  
neither this1 nor any other effect can  
be produced without a cause4  ,infinite 
divisibility is a necessary property of 
all extended substance2 and from this   
circumstance it will follow1 that the   
smallest quantity of solid matter may be
 made to fill the largest space1 and yet
 none of the pores shall exceed the     
smallest given magnitude2 and           
consequently1 that1 for any thing we    
know to the contrary1 all the bodies in 
the universe may be comprized in the    
smallest space4  ,another property      
usually ascribed to all matter is       
impenetrability1 or the necessary       
exclusion of any substance from the     
place occupied by another4 ,but the only
 proof of impenetrability is the        

resistance that we find to our          
endeavours to put one substance into the
 place of another2 and it is            
demonstrated by experiments1 that this  
resistance is not occasioned by the     
actual contact of the substances1 but by
 a power of repulsion acting at a real  
distance from their surfaces4 ,it       
requires a considerable force to bring  
two solid substances into as near       
contact as the particles of the same    
substance2 and that these are not in    
actual contact is evident1 from their   
being capable of being brought nearer by
 cold2 and this is most remarkable with 
respect to the heaviest1 that is1 the   
densest1 of all substances1 viz4 the    
metals4  ,a more positive argument for  
the penetrability of matter is1 that the
 particles of light1 after entering the 
densest transparent substance1 do not   
appear to meet with any obstruction to  
their progress till they come to the    
opposite side4  ,the powers of          
attraction and repulsion seem to be     

common to all matter1 and the component 
parts of all substances are kept in     
their places by the due balance of those
 opposite powers4 ,if1 by any means1 the
 particles of any substance be removed  
beyond their sphere of mutual           
attraction1 they repel one another1 as  
those of water when it becomes steam4   
,of the different kinds of attraction1  
that of gravitation seems to extend to  
the greatest possible distance2 but that
 which keeps together the parts of the  
same substance1 thence called the       
attraction of cohesion1 and the         
different kinds of chemical attractions1
 called affinities1 only act at a small 
distance4 ,of the causes of these       
attractions we are entirely ignorant4   
,of ,aeriform ,substances4  ,aeriform   
substances1 of which the air that we    
breathe is one1 though invisible1 are   
real substances1 as appears by their    
excluding other substances4  ,that the  
air has weight appears by actually      
weighing a vessel before and after it is

 exhausted of air by means of an        
air-pump 7an instrument contrived for   
that purpose7 by its bursting a bladder1
 and various other experiments4  ,air1  
being a fluid1 presses in all           
directions1 as in the experiment of the 
fountain in vacuo1 and others4  ,the    
weight of the air is the cause of the   
suspension of mercury in a barometer1   
and of the action of pumps4 ,the weight 
of atmospherical air is to that of water
 in the proportion of about #a to #hjj1 
so as to press with the weight of about 
fourteen pounds on every square inch of 
surface4  ,air1 being an elastic fluid1 
is capable of occupying more or less    
space according to the pressure which it
 sustains1 as appears by a bladder      
partially filled with air being expanded
 when the air is drawn from a receiver  
in which it is put1 by means of the     
air-pump1 and compressed in the         
condensing engine1 an instrument the    
reverse of the air-pump4  ,air is       
necessary to the conveyance of sound1 to

 the existence of flame1 and to animal  
life4     ,,lecture ,,iii4   ,of        
,atmospherical ,air4  ,the first species
 of air that offers itself to our       
consideration is that of the atmosphere1
 which appears to consist of a mixture  
of two kinds of air1 of different and   
opposite qualities1 viz41               
dephlogisticated and phlogisticated1 in 
the proportion of about one third of the
 former to two thirds of the latter4 ,it
 is by means of the former of these two 
ingredients that it is capable of       
supporting flame and animal life4  ,this
 composition of atmospherical air is    
proved by several substances absorbing  
the dephlogisticated air1 and leaving   
the phlogisticated4 ,all these processes
 have been termed phlogistic1 because   
the effect is not produced but by       
substances supposed to contain          
phlogiston in a volatile state2 and by  
the affinity between phlogiston and the 
dephlogisticated part of the air1 the   
one is separated from the other4 ,of    

these processes are the calcination of  
metals1 a mixture of iron-filings and   
sulphur1 liver of sulphur1 the burning  
of phosphorus1 and the effluvia of      
flowers4  ,in some cases1 however1 it is
 not so clear that any thing is emitted 
from the substance that produces this   
effect2 for water deprived of all air   
will absorb the dephlogisticated part of
 the atmospherical in preference to the 
phlogisticated part4  ,as the purity of 
atmospherical air1 or its fitness for   
respiration1 depends upon the proportion
 of the dephlogisticated air that it    
contains1 any of the above-mentioned    
processes will suffice to determine it4 
,the more any given quantity of air is  
diminished by any of them1 the purer it 
was before the diminution4 ,but this    
effect is produced the most quickly by a
 mixture of nitrous air1 or firing      
inflammable air in it1 being almost     
instantaneous4  ,in order to measure the
 purity of air1 it is convenient to take
 more of the nitrous or inflammable air 

than is necessary to saturate the       
dephlogisticated air it contains4 ,equal
 quantities of each best answer the     
purpose4 ,supposing a given quantity of 
atmospherical air to be mixed with an   
equal quantity of nitrous air1 and the  
residuum to be #a4a measure1 the        
proportion of dephlogisticated and      
phlogisticated air in it may be found by
 the following arithmetical operation1  
it being here taken for granted that one
 measure of pure dephlogisticated air   
will saturate two measures of pure      
nitrous air4        #b4j viz4 one of    
each4       #a4a the residuum4          
-----     #c7j4i the quantity that has  
disappeared4       #j4c the             
dephlogisticated air contained          
in the measure of the air examined4     
,and this substracted from #a leaves 4#g
 for the proportion of phlogisticated   
air in it4     ,,lecture ,,iv4   ,of    
,dephlogisticated ,air4                 
,dephlogisticated air1 which is one of  
the component parts of atmospherical    

air1 is a principal element in the      
composition of acids1 and may be        
extracted by means of heat from many    
substances which contain them1          
especially the nitrous and vitriolic2 as
 from nitre1 red precipitate1 the       
vitriols1 and turbith mineral1 and also 
from these two acids themselves1 exposed
 to a red heat in an earthen tube4 ,this
 kind of air is also contained in       
several substances which had attracted  
it from the atmosphere1 as from         
precipitate per se1 minium1  manganese4 
,dephlogisticated air is likewise       
produced by the action of light upon    
green vegetables2 and this seems to be  
the chief means employed by nature to   
preserve the purity of the atmosphere4  
,it is this ingredient in atmospheric   
air that enables it to support          
combustion and animal life4 ,by means of
 it the most intense heat may be        
produced1 and in the purest of it       
animals will live nearly five times as  
long as in an equal quantity of         

atmospherical air4  ,in respiration1    
part of this air1 passing the membrane  
of the lungs1 unites with the blood1 and
 imparts to it its florid colour1 while 
the remainder1 uniting with phlogiston  
exhaled from the venous blood1 forms    
fixed air4 ,it is dephlogisticated air  
combined with water that enables fishes 
to live in it4  ,dephlogisticated air is
 something heavier than atmospherical   
air1 and the purity of it measured by   
mixing with it two equal quantities of  
nitrous or inflammable air1 deducing the
 residuum after the diminution from the 
three measures employed1 and dividing   
the remainder by #c1 as in the process  
for common air4   ,of ,phlogisticated   
,air4  ,the other ingredient in the     
composition of atmospherical air is     
phlogisticated air4 ,it is procured by  
extracting the dephlogisticated part of 
the common air1 as by the calcination of
 metals1 c4 c4 by dissolving animal     
substances in nitrous acid1 and also by 
the union of phlogiston with nitrous    

air1 as by heating iron in it1 and by a 
mixture of iron-filings and sulphur4    
,phlogisticated air extinguishes a      
candle1 is entirely unfit for           
respiration1 and is something lighter   
than common air4 ,it is not capable of  
decomposition1 except by exploding it   
together with a superabundance of       
dephlogisticated air1 and a quantity of 
inflammable air1 or by taking the       
electric spark repeatedly in a mixture  
of it and dephlogisticated air4 ,in     
these cases nitrous acid is formed4     
,,lecture ,v4   ,of ,inflammable ,air4  
,inflammable air is procured from all   
combustible substances by means of heat 
and water1 and from several of the      
metals1 especially iron1 zink1 and tin1 
by the vitriolic and marine acids4      
,from oils and spirit of wine it is     
procured by the electric spark4 ,by the 
same means also alkaline air is         
converted into it4  ,that which is      
procured from metals1 especially by     
steam1 is the purest and the lightest1  

about ten times lighter than common air2
 in consequence of which1 if a          
sufficient quantity be confined in a    
light covering1 it is possible to make  
it carry up heavy weights4  ,when it is 
procured from animal or vegetable       
substances1 it is of a heavier kind1 and
 burns with a lambent flame1 of various 
colours1 according to the circumstances4
  ,calces of metals heated in           
inflammable air are revived1 and the air
 absorbed2 and since all the metals are 
revived in the same inflammable air1 the
 principle of metallization1 or         
phlogiston1 appears to be the same in   
them all4  ,pure inflammable air seems  
to consist of phlogiston and water1 and 
the lambent kinds to be the same thing1 
with the addition of some oily vapour   
diffused through it4     ,,lecture ,,vi4
   ,of ,nitrous ,air4  ,nitrous air is  
procured by dissolving most of the      
metals1 especially iron1 mercury1 and   
copper1 in the nitrous acid2 but that   
from mercury seems to be the purest4    

,nitrous air produced from copper       
contains a mixture of phlogisticated    
air4 ,some nitrous air is also obtained 
from the solution of all vegetable      
substances in nitrous acid2 whereas     
animal substances in the same process   
yield chiefly phlogisticated air3 but in
 both these cases there is a mixture of 
fixed air4  ,this species of air is     
likewise produced by impregnating water 
with nitrous vapour4 ,this process      
continues to have this effect after the 
water becomes blue1 but ceases when it  
turns green2 there not then1 probably1  
being a sufficient proportion of water4 
,nitrous air is likewise produced by    
volatile alkali passing over red hot    
manganese1 or green vitriol1 when they  
are yielding dephlogisticated air4 ,this
 shews that dephlogisticated air is one 
ingredient in the composition of nitrous
 air1 and the same thing appears by     
pyrophorus burning in it4 ,on the       
contrary1 when nitrous air is made to   
pass over red-hot iron1 volatile alkali 

is produced4  ,nitrous air is completely
 decomposed by a mixture of about half  
its bulk of dephlogisticated air1 and   
the produce is nitrous acid4 ,and as    
nitrous acid is likewise formed by the  
union of inflammable and                
dephlogisticated air1 one principal     
ingredient in nitrous air must be common
 to it and inflammable air1 or          
phlogiston4 ,this air is likewise       
decomposed by dephlogisticated nitrous  
acid1 which by this means becomes       
phlogisticated4 ,it is also decomposed  
by a solution of green vitriol1 which by
 this means becomes black1 and when     
exposed to the air1 or heated1 emits    
nitrous air1 and recovers its former    
colour4 ,these decompositions of nitrous
 air seem to be effected by depriving it
 of phlogiston1 and thereby reducing it 
to the phlogisticated air originally    
contained in it4  ,this kind of air is  
diminished to about one fourth of its   
bulk by a mixture of iron filings and   
brimstone1 or by heating iron in it1 or 

calcining other metals in it1 when the  
remainder is phlogisticated air4 ,all   
that iron gets in this process is an    
addition of weight1 which appears to be 
water1 but it loses its phlogiston1 so  
that nitrous air seems to contain more  
phlogiston1 and less water than         
phlogisticated air4  ,nitrous air and   
dephlogisticated air will act upon one  
another through a bladder1 but in this  
case there remains about one-fourth of  
the bulk of nitrous air1 and that is    
phlogisticated air2 so that in this case
 there seems to be a conversion of      
nitrous air into phlogisticated air     
without any addition of phlogiston4     
,nitrous air is decomposed by           
pyrophorus1 and by agitation in olive   
oil1 which becomes coagulated by the    
process4 ,it is also absorbed by spirit 
of turpentine1 by ether1 by spirit of   
wine1 and alkaline liquors4  ,it is     
imbibed by charcoal1 and both that air  
which is afterwards expelled from it by 
heat1 and that which remains unabsorbed1

 is phlogisticated air4  ,nitrous air   
resists putrefaction1 but is diminished 
by the animal substances exposed to it  
to about a fourth of its bulk1 and      
becomes phlogisticated air4 ,it is      
likewise fatal to plants1 and           
particularly to insects4  ,when nitrous 
air is long exposed to iron1 it is      
diminished and brought into a state in  
which a candle will burn in it1 though  
no animal can breathe it4 ,but this     
peculiar modification of nitrous air1   
called dephlogisticated nitrous air1 is 
produced with the greatest certainty by 
dissolving iron in spirit of nitre      
saturated with copper1 impregnating     
water with this air1 and then expelling 
it from the water by heat4 ,if bits of  
earthen ware be heated in this          
dephlogisticated nitrous air1 a great   
proportion of it becomes permanent air1 
not miscible with water1 and nearly as  
pure as common air1 so that the         
principle of heat seems to be wanting to
 constitute it permanent air4           

,,lecture ,,vii4   ,of ,fixed ,air4     
,having considered the properties of    
those kinds of air which are not readily
 absorbed by water1 and therefore may be
 confined by it1 ,i proceed to those    
which are absorbed by it1 and which     
require to be confined by mercury4      
,there are two kinds1 however1 in a     
middle state between these1 being       
absorbed by water1 but not very readily2
 a considerable time1 or agitation1     
being necessary for that purpose4 ,the  
first of these is fixed air4  ,this kind
 of air is obtained in the purest state 
by dissolving marble1 lime-stone1 and   
other kinds of mild calcareous earth in 
any acid4 ,it is also obtained by the   
burning1 or the putrefaction1 of both   
animal and vegetable substances1 but    
with a mixture of both phlogisticated   
and inflammable air4 ,fixed air is also 
produced by heating together iron       
filings and red precipitate2 the former 
of which would alone yield inflammable  
air1 and the latter dephlogisticated4   

,fixed air is therefore a combination of
 these two kinds of air4  ,another fact 
which proves the same thing is1 that if 
charcoal of copper be heated in         
dephlogisticated air1 almost the whole  
of it will be converted into fixed air4 
,on the same principle fixed air is     
produced when iron1 and other           
inflammable substances1 are burned in   
dephlogisticated air1 and also when     
minium1 and other substances containing 
dephlogisticated air1 are heated in     
inflammable air4  ,that water is an     
essential part of fixed air is proved by
 an experiment upon terra ponderosa     
aerata1 which yields fixed air when it  
is dissolved in an acid1 but not by mere
 heat4 ,if steam1 however1 be admitted  
to it in that state1 it will yield as   
much fixed air as when it is dissolved  
in an acid4  ,water absorbs something   
more than its own bulk of fixed air1 and
 then becomes a proper acid4 ,iron      
dissolved in this water makes it a      
proper chalybeate2 as without iron it is

 of the same nature with ,pyrmont or    
,seltzer water1 which by this means may 
be made artificially4  ,ice will not    
imbibe this air1 and therefore freezing 
expels it from water4  ,fixed air       
extinguishes flame1 and is fatal to     
animals breathing in it4 ,also water    
impregnated with this air is fatal to   
fishes1 and highly injurious to plants4 
,but water thus impregnated will        
prevent1 in a great measure1 the        
putrefaction of animal substances4      
,fixed air thrown into the intestines1  
by way of glyster1 has been found to    
give relief in some cases of putrid     
disease4   ,of ,hepatic ,air4  ,another 
species of air absorbed by water1 but   
not instantly1 is termed hepatic air1   
being produced by the solution of liver 
of sulphur1 or of sulphurated iron1 in  
vitriolic or marine acid4  ,water       
imbibes about twice its bulk of this    
kind of air1 and it is then the same    
thing with the sulphureous waters of    
,harrowgate4   ,of ,phosphoric ,air4    

,phosphoric air is produced by the      
solution of phosphorus in caustic fixed 
alkali4 ,if this air be confined by     
mercury1 it will take fire on being     
admitted to atmospheric1 and much more  
to dephlogisticated air4 ,after         
agitation in water it loses this        
property1 and the residuum is merely    
inflammable air1 with no great          
diminution of its bulk4 ,this kind of   
air1 therefore1 probably consists of    
phosphorus dissolved in inflammable air2
 though it cannot be made by melting it 
in inflammable air4     ,,lecture       
,,viii4   ,of ,dephlogisticated ,marine 
,acid ,air4  ,this species of air is    
produced by heating spirit of salt with 
manganese2 or more readily1 by pouring  
acid of vitriol on a mixture of salt and
 manganese1 in the proportion of about  
#af of the former to #f of the latter4  
,in this case the acid of vitriol       
decomposes the salt1 and the marine     
acid1 disengaged in the form of air1    
takes dephlogisticated air from the     

manganese2 so that this species of air  
seems to consist of marine acid vapour1 
and dephlogisticated air4  ,this species
 of air has a peculiarly pungent smell1 
and is absorbed by water as readily as  
fixed air4  ,the water takes about twice
 its bulk of it2 and thereby acquires a 
yellowish tinge4 ,both this air1 and the
 water impregnated with it1 discharges  
vegetable colours from linen or cotton1 
and is thereby useful in bleaching4     
,this air when cold coagulates into a   
yellowish substance4 ,it dissolves      
mercury1 and with it forms corrosive    
sublimate4   ,of ,phlogisticated ,marine
 ,acid ,air4  ,besides the preceding    
kinds of air which are slowly absorbed  
by water1 there are others which are    
absorbed by it very rapidly1 so that    
they cannot be confined but by mercury4 
,of this kind is phlogisticated marine  
acid air1 procured by the acid of       
vitriol and common salt2 the former     
seizing upon the alkaline basis of the  
latter1 and thereby expelling the marine

 acid in the form of air4  ,it is called
 phlogisticated to distinguish it from  
dephlogisticated marine acid air1 which 
seems to be the same thing1 with the    
addition of dephlogisticated air4       
,phlogisticated marine acid air is      
heavier than common air4 ,it            
extinguishes a candle with a blue flame4
 ,it dissolves many substances          
containing phlogiston1 as iron1 dry     
flesh1 c4 and thereby forms a little    
inflammable air4 ,water absorbs #cfj    
times its bulk of this air1 and is then 
the strongest spirit of salt4 ,it       
absorbs one-sixth more than its bulk of 
alkaline air1 and with it forms the     
common sal ammoniac4 ,its affinity to   
water enables it to dissolve ice1 and to
 deprive borax1 nitre1 and other saline 
substances1 of the water that enters    
into their composition4     ,,lecture   
,,ix4   ,of ,vitriolic ,acid ,air4      
,vitriolic acid air is procured by      
heating in hot acid of vitriol almost   
any substance containing phlogiston1    

especially the metals which are soluble 
in that acid1 as copper1 mercury1 c4    
,this kind of air is heavier than common
 air1 and extinguishes a candle1 but    
without any particular colour of its    
flame4 ,it will not dislodge the nitrous
 or marine acids from any substance     
containing them4  ,by its affinity to   
water it deprives borax of it4  ,one    
measure of this air saturates two of    
alkaline air1 and with it forms the     
vitriolic ammoniac4  ,water imbibes     
between #cj and #dj times its bulk of   
this air1 and retains it when frozen4   
,water thus impregnated dissolves some  
metals1 and thereby yields inflammable  
air4  ,if this water be confined in a   
glass tube1 together with common air1   
and be exposed to a long continued heat1
 it forms real sulphur1 the             
dephlogisticated part of the common air 
being imbibed1 and forming real         
vitriolic acid1 which uniting with the  
phlogiston in the air1 forms the        
sulphur4 ,also this air mixed with      

atmospheric air will1 without heat1     
imbibe some part of it1 and thereby     
become the common acid of vitriol2 so   
that water impregnated with vitriolic   
acid air1 commonly called sulphureous1  
or phlogisticated acid of vitriol1 wants
 dephlogisticated air to make it the    
common acid of of vitriol4  ,this kind  
of air is imbibed by oils1 which thereby
 change their colour2 whale oil becoming
 red1 olive oil of an orange colour1 and
 spirit of turpentine of the colour of  
amber4  ,if this air be confined in a   
glass tube by mercury1 and the electric 
spark be taken in it1 a black tinge will
 be given to the glass contiguous to the
 spark1 and this black substance appears
 to be mercury super-phlogisticated2    
since by exposure to air it becomes     
running mercury3 so that the vapour of  
mercury must be diffused through every  
part of this air1 to the distance of at 
least several feet from the surface of  
the mercury4   ,of ,fluor ,acid ,air4   
,fluor acid air is procured by          

dissolving the earthy substance called  
fluor in vitriolic acid4  ,this kind of 
air extinguishes a candle1 and1 like    
vitriolic acid air1 one measure of it   
saturates two of alkaline air4 ,it is   
peculiar to this kind of air to dissolve
 glass when it is hot4  ,it seems to    
consist of a peculiar acid vapour united
 to the stony substance of the fluor2   
for water being admitted to it absorbs  
the acid vapour1 and the stony substance
 is deposited4 ,by this means it        
exhibits an amusing appearance1 whether 
water be admitted to a glass jar        
previously filled with that air1 or the 
bubbles of air be admitted1 as they are 
formed1 to a quantity of water resting  
on mercury4     ,,lecture ,x4   ,of     
,alkaline ,air4  ,alkaline air is       
produced by means of heat from caustic  
volatile alkali1 and also from a mixture
 of sal-ammoniac and slaked lime1 in the
 proportion of about one-fourth of the  
former to three-fourths of the latter4  
,in this case the marine acid in the    

sal-ammoniac unites with the calcareous 
earth1 and the volatile alkali 7probably
 with the assistance of the water7 takes
 the form of air4  ,this species of air 
is heavier than inflammable air1 but    
lighter than any of the acid airs4 ,like
 them1 however1 it dissolves ice1 and   
deprives alum1 and some other saline    
substances1 of the water which they     
contain4 ,united with fixed air1 it     
makes the concrete volatile alkali2 with
 marine acid air1 the common            
sal-ammoniac2 and with water1 the       
caustic volatile alkali4  ,the electric 
spark1 or a red heat1 converts alkaline 
air into three times its bulk of        
inflammable air2 and the calces of      
metals are revived in alkaline1 as well 
as in inflammable air2 but there remains
 about one-fourth of its bulk of        
phlogisticated air4 ,these facts shew   
that alkaline air consists chiefly of   
phlogiston4   ,miscellaneous            
,observations relating to ,air4  ,the   
nitrous acid may be exhibited in the    

form of air1 as well as the vitriolic1  
the marine1 and the fluor acids4 ,but it
 cannot be confined even by mercury1    
which it instantly dissolves4 ,it may1  
however1 in some measure1 be confined in
 a dry glass vessel1 from which it will 
in a great measure expel the common air4
 ,this nitrous acid air is that red     
vapour1 which is produced by the rapid  
solution of bismuth1 and some other     
metals in the nitrous acid4 ,but the    
vegetable acid cannot be exhibited in   
the form of air4 ,it is only capable of 
being converted into vapour1 like water3
 and in the common temperature of our   
atmosphere1 returns to a state of       
fluidity4  ,different kinds of air which
 have no affinity to each other1 when   
once mixed together will not separate1  
notwithstanding any difference of       
specific gravity4 ,such is the case of a
 mixture of inflammable and             
dephlogisticated air1 and even of       
inflammable and fixed air4 ,without this
 property also1 the phlogisticated air1 

which constitutes the greatest part of  
our atmosphere1 being specifically      
lighter than dephlogisticated air1 of   
which the other part of it consists1    
would separate from it1 and ascend into 
the higher regions of the atmosphere4   
,inflammable air1 however1 will not mix 
with acid or alkaline air4  ,different  
kinds of air are expanded differently by
 the same degrees of heat2              
dephlogisticated air the least1 and     
alkaline air the most4  ,if any fluid1  
as water1 spirit of wine1 or even       
mercury1 be heated in a porous earthen  
vessel1 surrounded by any kind of air1  
the vapour of the fluid will pass       
through the vessel one way1 while the   
air passes the other2 and when the      
operation ceases1 with respect to the   
one1 it likewise ceases with respect to 
the other4     ,,lecture ,,xi4   ,of    
,liquid ,substances2  ,,and ,,first ,,of
  ,,water4  ,having considered all the  
substances that are usually found in the
 form of air1 ,i come to those that are 

generally in a fluid form1 beginning    
with water1 which is the principal1 if  
not the only cause of fluidity to all   
the other substances that ,i shall place
 in this class4  ,pure water is a liquid
 substance1 transparent1 without colour1
 taste1 or smell2 and with different    
degrees of heat and cold may be made to 
assume the three forms of a solid1 of a 
fluid1 and of air4 ,below #cb deg4 of   
,fahrenheit it is ice1 and above #bab   
deg4 it is vapour2 so that in an        
atmosphere below #cb deg4 it never could
 have been known to be any thing else   
than a peculiar kind of stone1 and above
 #bab deg4 a peculiar species of air4   
,in passing from the state of a solid to
 that of a liquid1 water absorbs a great
 quantity of the principle1 or matter1  
of heat1 which remains in it in a latent
 state2 and in passing from a state of  
fluid to that of vapour1 it absorbs much
 more2 and this heat is found when the  
processes are reversed4 ,it has been    
observed1 that when water becomes       

vapour1 it takes the form of small      
globules1 hollow within1 so as to be    
specifically lighter than air4  ,the    
degree of heat at which water is        
converted into vapour depends upon the  
pressure of the atmosphere2 so that in  
vacuo1 or on the top of a high mountain1
 it boils with little heat2 and when    
compressed1 as in ,papin's digester1 or 
in the bottom of a deep pit1 it requires
 much heat4 ,in the former case the     
restoring of the pressure will instantly
 put a stop to the boiling1 and in the  
latter case the removing of the pressure
 will instantly convert the heated water
 into vapour4  ,the ease with which     
water is converted into vapour by heat1 
has given a great power to mechanicians1
 either by employing the natural        
pressure of the atmosphere1 when steam  
is condensed under a moveable pistern1  
in an iron cylinder1 which was the      
principle of the old fire-engine1 or by 
employing the elastic power of steam to 
produce the same effect1 which is the   

principle of ,mr4 ,watt's steam engine4 
,water was long thought to be           
incompressible by any external force1   
but ,mr4 ,canton has shewn that even the
 pressure of the atmosphere will        
condense it very sensibly4  ,we do not  
know any external force equal to that by
 which water is expanded when it is     
converted into ice1 or into vapour4 ,for
 though the particles of water approach 
nearer by cold1 yet when it             
crystallizes1 the particles arrange     
themselves in a particular manner1 with 
interstices between them2 so that1 on   
the whole1 it takes up more room than   
before4  ,water has an affinity to1 and 
combines with1 almost all natural       
substances1 aerial1 fluid1 or solid2 but
 most intimately with acids1 alkalies1  
calcareous earth1 and that calx of iron 
which is called finery cinder1 from     
which the strongest heat will not expel 
it4  ,it has been supposed by some1 that
 by frequent distillation1 and also by  
agitation1 water may be converted into a

 kind of earth2 but this does not appear
 to be the case4 ,it has also of late   
been thought1 that water is resolvable  
into dephlogisticated and inflammable   
air2 but the experiments which have been
 alleged to prove this do not satisfy   
me2 so that1 for any thing that appeared
 till very lately1 water might be       
considered as a simple element4 ,by     
means of heat1 however1 it seems to be  
resolvable into such air as that of     
which the atmosphere consists1 viz4     
dephlogisticated and phlogisticated1    
only with a greater proportion of the   
former4  ,water1 with respect to        
specific gravity and temperature1 has   
generally been made the standard to all 
other substances2 its freezing and      
boiling points being the limits by means
 of which thermometers are graduated4   
,other substances have also been        
compared with water1 as a standard1 with
 respect to the capacity of receiving   
heat1 and retaining it in a latent      
state1 as will be shewn when we consider

 the subject of heat4     ,,lecture     
,,xii4   ,of the ,nitrous ,acid4  ,under
 the head of liquids ,i shall consider  
acids and alkalis1 though some of them  
may be exhibited in the form of air1 and
 others in a solid form4 ,these two     
chemical principles are formed to unite 
with one another1 and then they         
constitute what is called a neutral     
salt4  ,both acids and alkalis are      
distinguishable by their taste4 ,another
 test1 and more accurate1 is1 that acids
 change the blue juices of vegetables   
red1 and alkalis turn the syrup of      
violets green4  ,acids are generally    
distinguished according to the three    
kingdoms to which they belong1 viz4     
mineral1 vegetable1 and animal4 ,the    
mineral acids are three1 the nitrous1   
the vitriolic1 and the marine4  ,the    
nitrous acid is formed by the union of  
the purest inflammable air1 or the      
purest nitrous air1 with                
dephlogisticated air4 ,but it is usually
 procured from nitre by means of the    

vitriolic acid1 which1 seizing its base1
 expels the nitrous acid in a liquid    
form4 ,on this account this acid is said
 to be weaker than the vitriolic4  ,if  
the nitrous acid be made to pass through
 a red-hot earthen tube1 it will be     
decomposed1 and the greatest part of it 
be converted into dephlogisticated air4 
,like all other acids1 the nitrous acid 
has a strong affinity to water2 but it  
is not capable of so much concentration 
as the vitriolic4 ,it is generally of an
 orange or yellow colour2 but heat will 
expel this colour in the form of a red  
vapour1 which is the same acid in the   
form of air1 and loaded with phlogiston2
 and therefore when it is colourless it 
is said to be dephlogisticated4 ,but the
 colourless vapour exposed to heat1 or  
to light1 will become coloured again2   
and the liquid acid imbibing this       
coloured vapour1 becomes coloured as    
before4 ,this acid tinges the skin of a 
yellow colour1 which does not disappear 
till the epidermis be changed4  ,the    

nitrous acid unites with phlogiston1    
alkalis1 metallic substances1 and       
calcareous earth4  ,by means of its     
affinity with phlogiston it occasions   
that rapid accension called detonation1 
when any salt containing this acid1     
especially nitre1 is applied to hot     
charcoal1 or when charcoal is put to hot
 nitre4 ,in fact1 the charcoal burns so 
rapidly by means of the dephlogisticated
 air supplied by the nitre4  ,a mixture 
of sulphur assists the accension of     
these substances1 and makes gunpowder1  
in the explosion of which much nitrous  
or phlogisticated air is suddenly       
produced1 and expanded by the heat4 ,the
 application of this force1 both to     
useful and destructive purposes1 is well
 known4 ,if1 instead of nitre1 a salt   
made with dephlogisticated marine acid  
be made use of1 the explosion is more   
easily produced1 and is much more       
violent4 ,friction will do this as well 
as heat4  ,nitre also enters into the   
composition of pulvis fulminans1 viz4   

three parts nitre1 two of dry alkali1   
and one of sulphur4 ,this composition   
melts1 and yields a blue flame1 before  
it explodes4  ,by means of the affinity 
of the nitrous acid to oil1 another     
substance containing phlogiston1 it is  
capable of producing not only a great   
heat1 but even a sudden flame1          
especially when mixed with a little     
vitriolic acid4  ,nitrous acid dissolves
 all metallic substances except gold and
 platina1 and in the solution nitrous   
air is produced4  ,the particular kinds 
of saline substances formed by the union
 of the nitrous acid with the several   
metals and earths may be seen in tables 
constructed for the purpose4 ,they are  
all deliquescent4     ,,lecture ,,xiii4 
,of the ,vitriolic ,acid4  ,the         
vitriolic acid1 so called because it was
 originally procured from vitriol1 is   
now generally procured from sulphur2 the
 dephlogisticated part of the air       
uniting with it in the act of burning4  
,that dephlogisticated air is essential 

to this acid is evident from the        
decomposition of it2 for if the vapour  
of it be made to pass through a red-hot 
earthen tube1 a great quantity of       
dephlogisticated air is procured4  ,this
 acid has a strong affinity to water1   
with which it unites with much heat2 and
 it is capable of greater concentration1
 or of being made specifically heavier1 
than any other acid4 ,when pure1 it is  
entirely free from colour and smell1    
owing1 probably1 to its being free from 
phlogiston1 which is inseparable from   
the nitrous or marine acids4  ,the      
vitriolic acid will dislodge the        
nitrous1 or marine1 or any other acid1  
from their earthy or metallic bases2    
from which property it is called the    
strongest of all the acids4  ,by means  
of the superior affinity of the         
vitriolic acid to earths1 and especially
 to terra ponderosa1 the smallest       
quantity of it in water may be          
discovered by a solution of this earth  
in the marine acid4 ,in this acid the   

terra ponderosa is held in perfect      
solution2 but with the vitriolic acid it
 forms a substance that is insoluble in 
water1 and therefore it instantly       
appears in the form of a white cloud4   
,perhaps chiefly from the strong        
affinity which this acid has with water1
 pyrophorus1 consisting of a mixture of 
alum and several substances containing  
phlogiston1 takes fire spontaneously on 
exposure to the air4 ,it is commonly    
made of three parts of alum and one of  
brown sugar1 or of two parts alum1 one  
of salt of tartar1 and one of charcoal4 
,they must be heated till they have for 
some time emitted a vapour that burns   
with a blue flame4  ,the saline         
substances produced by the union of this
 acid with the several earths and       
metals1 are best exhibited in tables    
constructed for the purpose4 ,when      
united to three of the metals1 viz4     
iron1 copper1 and zinc1 they are called 
vitriols1 green1 blue1 and white4 ,and  
all the substances which this acid      

unites with crystallize1 and do not     
deliquesce4  ,this acid unites with oil1
 and the mixture is always black4  ,when
 any substance containing phlogiston is 
heated in the vitriolic acid1 another   
species of the acid1 called sulphureous1
 is formed1 of a pungent smell4 ,in     
reality1 it is water impregnated with   
vitriolic acid air4 ,it makes1 however1 
a distinct species of acid1 and is      
dislodged from its base by most of the  
others4   ,of the ,marine ,acid4  ,the  
marine acid is procured from common salt
 by the vitriolic acid1 which unites    
with its base1 the fossil alkali4  ,this
 acid is generally of a straw-colour2   
but this is owing to an impregnation    
with some earthy matter1 most of which  
it readily dissolves1 especially the    
metallic ones4 ,it is less capable of   
concentration than the vitriolic or     
nitrous acids1 perhaps from a more      
intimate union of phlogiston with it4   
,no heat can extract from it any        
dephlogisticated air4  ,though this is  

denominated a weaker acid than the      
nitrous1 yet it will take silver1 lead1 
or mercury1 from their union with the   
nitrous acid4 ,upon this principle1 a   
solution of these metals in the nitrous 
acid will readily discover whether any  
water contains the marine acid1 the     
latter uniting with the metal dissolved 
in the former1 and forming with it1 if  
it be silver1 a luna cornea2 which being
 a substance insoluble in water1        
discovers itself by a cloudy appearance4
  ,the union of the marine acid with    
earths forms salts that easily          
deliquesce1 but with the metals such as 
are capable of crystallization2 and so  
also is that formed by the union of this
 acid to terra ponderosa4  ,neither this
 acid nor the nitrous will dissolve gold
 or platina2 but a mixture of them1     
called aqua regia1 will do it4  ,the    
marine acid has a strong affinity to    
dephlogisticated air1 and will take it  
from manganese and other substances2 and
 with this union it becomes a different 

acid1 called dephlogisticated marine    
acid1 being water impregnated with      
dephlogisticated marine acid air1       
described above4     ,,lecture ,,xiv4   
,of the ,vegetable ,acids1 and others of
 a less perfect nature4  ,the principal 
of the vegetable acids are the acetous  
and the tartareous4 ,the acetous acid is
 the produce of a peculiar fermentation 
of vegetable substances1 succeeding the 
vinous1 in which ardent spirit it is    
procured1 and succeeded by the          
putrefactive1 in which volatile alkali  
is generated4  ,thus wine is converted  
into vinegar4 ,crude vinegar1 however1  
contains some ingredient from the       
vegetable substances from which it was  
procured3 but distillation separates    
them1 and makes the vinegar colourless2 
though some of the acid is lost in the  
process4  ,the acetous acid is          
concentrated by frost1 which does not   
affect the proper acid1 but only the    
water with which it is united4 ,it may  
likewise be concentrated by being first 

combined with alkalies1 earths1 or      
metals1 and then dislodged by a stronger
 acid1 or by mere heat4 ,thus the       
acetous acid1 combined with vegetable   
alkali1 forms a substance that is called
 the foliated earth of tartar2 and it   
may be expelled from it by the vitriolic
 acid4 ,when combined with copper it    
makes verdigris2 and from this union    
heat alone will expel it in a           
concentrated state4 ,the acetous acid   
thus concentrated is called radical     
vinegar4 ,still1 however1 it is weaker  
than any of the preceding mineral acids4
  ,several vegetables1 as lemons1       
sorrel1 and unripe fruit1 contain acids1
 ready formed by nature1 mixed with some
 of the essential oil of the plants1    
which gives them their peculiar         
flavours4 ,all these acids have peculiar
 properties2 but it is not necessary to 
note them in this very general view of  
the subject4 ,like vinegar1 these acids 
may be concentrated by frost1 and also  
by a combination with other substances1 

and then expelled by a stronger acid4   
,the acid of tartar is very similar to  
that of vinegar4 ,tartar1 from which it 
is procured1 is a substance deposited on
 the inside of wine-casks1 though it is 
also found ready formed in several      
vegetables4 ,it consists of the         
vegetable alkali and this peculiar acid4
 ,when refined from its impurities1 it  
is called crystals1 or cream of tartar4 
,the acid is procured by mixing the     
tartar with chalk1 or lime1 which       
imbibes the superfluous acid1 and this  
is expelled by the acid of vitriol4 ,or 
it may be procured by boiling the tartar
 with five or six times its weight of   
water1 and then putting the acid of     
vitriol to it4 ,this unites with the    
vegetable alkali1 and forms vitriolated 
tartar2 and the pure acid of tartar may 
be procured in crystals1 by evaporation 
and filtration1 equal in weight to half 
the cream of tartar4 ,this acid of      
tartar is more soluble in water than the
 cream of tartar4  ,this acid1 united to

 the mineral alkali1 makes ,rochelle    
salt4  ,every kind of wood1 when        
distilled1 or burned1 yields a peculiar 
acid2 and it is the vapour of this acid 
that is so offensive to the eyes in the 
smoke of wood4  ,a peculiar acid is     
obtained from most vegetable substances1
 especially the farinaceous ones1 and   
from sugar1 by distillation with the    
nitrous acid4 ,this seizes upon the     
substance with which the acid was       
united1 and especially the phlogiston   
adhering to it1 and then the peculiar   
acid of sugar crystallizes4 ,thus with  
three parts of sugar1 and thirty of     
nitrous acid1 one part of the proper    
acid of sugar may be obtained4 ,by the  
same process an acid may be procured    
from camphor4  ,the bark of oak1 and    
some other vegetable substances1        
especially nut-galls1 contain a         
substance which has obtained the name of
 the astringent principle2 the peculiar 
property of which is1 that it           
precipitates solutions of iron in the   

form of a black powder1 and in this     
manner ink is made4 ,but by solution in 
water and evaporation1 crystals1 which  
are a proper acid of galls1 may be      
obtained4  ,amber is a hard             
semitransparent substance1 chiefly found
 in ,prussia1 either dug out of the     
earth1 or thrown up by the sea4 ,it is  
chiefly remarkable for its electrical   
property2 but by distillation in close  
vessels there sublimes from it a        
concreted acid1 soluble in #bd times its
 weight of cold water4 ,amber seems to  
be of vegetable origin1 and to consist  
of an oil united to this peculiar acid4 
,the acids ,i shall mention next are of 
a mineral origin2 but being of a less   
perfect nature as acids1 ,i shall only  
just note them here4  ,borax is a       
substance chiefly found in a            
crystallized state in some lakes in the 
,east ,indies4 ,it consists of the      
mineral alkali and a peculiar acid1     
which may be separated1 and exhibited in
 white flakes1 by putting acid of       

vitriol to a solution of it in water4   
,this acid has been called sedative     
salt1 from its supposed uses in         
medicine4 ,it is an acid that requires  
fifty times its weight of water to      
dissolve it4  ,several other mineral    
substances1 as arsenic1 molybdena1      
tungsten1 and wolfram1 in consequence of
 being treated as the preceding         
vegetables ones1 have been lately found 
to yield peculiar acids4 ,they are also 
produced in a concrete state1 and       
require a considerable proportion of    
water to make them liquid2 but as the   
water in which they are dissolved turns 
the juice of litmus red1 and as they    
also unite with alkalis1 they have all  
the necessary characteristics of acids4 
,,lecture ,,xv4   ,of the ,phosphoric   
,acid4  ,the most important acid of     
animal origin1 though it has lately been
 found in some mineral substances1 is   
the phosphoric4  ,phosphorus itself is a
 remarkable substance1 much resembling  
sulphur1 but much more inflammable4 ,it 

has been procured chiefly1 till of late1
 from urine1 but now more generally from
 bones1 by means of the vitriolic acid1 
which unites with the calcareous earth  
of which bones consist1 and sets at     
liberty the phosphoric acid1 or the base
 of that acid1 with which it was        
naturally combined4 ,the acid thus      
procured1 mixed with charcoal1 and      
exposed to a strong heat1 makes         
phosphorus4  ,this substance burns with 
a lambent flame in the common           
temperature of our atmosphere1 but with 
a strong and vivid flame if it be       
exposed to the open air when moderately 
warm4 ,in burning it unites with the    
dephlogisticated air of the atmosphere1 
and in this manner the purest phosphoric
 acid is produced4  ,this acid is also  
procured in great purity by means of the
 nitrous or vitriolic acids1 especially 
the former1 which readily combines with 
the phlogiston of the phosphorus1 and   
thus leaves the acid pure4 ,in this     
process phlogisticated air is produced4 

,this acid is perfectly colourless1 and 
when exposed to heat loses all its      
water1 and becomes a glassy substance1  
not liable to be dissipated by fire1 and
 readily uniting with earths4  ,united  
to the mineral alkali1 it forms a       
neutral salt1 lately introduced into    
medicine4 ,united to the mineral and    
vegetable alkalis naturally contained in
 urine1 it has obtained the name of     
microcosmic salt1 frequently used as a  
flux for mineral substances with a      
blow-pipe4  ,besides the phosphoric1    
there are other acids of an animal      
origin2 as that of milk1 that of sugar  
of milk1 that of the animal calculus1   
and that of fat4  ,the acid of milk is  
the sour whey contained in butter-milk1 
which1 by a tedious chemical process1   
may be obtained pure from any foreign   
substance4  ,the sugar of milk is       
procured by evaporating the whey to     
dryness1 then dissolving it in water1   
clarifying it with whites of eggs1 and  
evaporating it to the consistence of    

honey4 ,in this state white crystals of 
the acid of sugar of milk will be       
obtained4  ,by distilling these crystals
 with nitrous acid1 other crystals of   
the proper acid of sugar of milk will be
 obtained1 similar to those of the acid 
of sugar4  ,if the human calculus be    
distilled1 it yields a volatile alkali1 
and something sublimes from it which has
 a sourish taste1 and therefore called  
the acid of the calculus4 ,it is        
probably some modification of the       
phosphoric acid4  ,animal fat yields an 
acid by distillation1 or by first       
combining it with quick-lime1 and then  
separating it by the vitriolic acid4    
,siliceous earth is corroded by this    
acid4     ,,lecture ,,xvi4   ,of        
,alkalis4  ,the class of substances that
 seems particularly formed by nature to 
unite with acids1 and thereby form      
neutral salts1 are the alkalis4 ,they   
have all a peculiar acrid taste1 not    
easily defined4 ,they change the blue   
juices of vegetables green1 or purple1  

and in common with acids have an        
affinity with water1 so as to be capable
 of being exhibited in a liquid form2   
though when this water is expelled by   
heat1 some of them will assume a solid  
form4  ,alkalis are of two kinds2 the   
fixed1 which have no smell1 and the     
volatile which have a pungent one4  ,the
 fixed alkalis are of vegetable or      
mineral origin4 ,when in a solid form1  
they both melt with a moderate heat1 and
 uniting with earthy substances1 make   
glass4 ,with an intense heat they are   
volatilized4  ,vegetable alkali is      
procured by burning plants1 and         
lixiviating the ashes2 a purer kind by  
the burning of tartar1 hence called salt
 of tartar2 but the purest of all is got
 by the deflagration of nitre2 the      
charcoal uniting with the acid as it    
assumes the form of dephlogisticated    
air1 and the alkali being left behind4  
,mineral alkali is found in ashes of    
sea-weed4 ,it is likewise the basis of  
sea-salt2 from which it is separated by 

several processes1 but especially by the
 calx of lead1 which has a stronger     
affinity with the marine acid with which
 it is found combined4  ,alkalis united 
with fixed air are said to be mild1 and 
when deprived of it caustic1 from their 
readiness to unite with1 and thereby    
corrode1 vegetable and animal           
substances4 ,to render them caustic1    
they are deprived of their fixed air by 
quick-lime2 and in this state they unite
 with oils1 and make soap4  ,alkalis    
have a stronger affinity with acids than
 metals have with them2 so that they    
will precipitate them from their        
solutions in acid menstruums4  ,the     
vegetable fixed alkali has a strong     
attraction to water1 with which it will 
become saturated in the common state of 
our atmosphere1 when it is said to      
deliquesce2 and having the appearance of
 oil1 the salt of tartar is thus said to
 become oil of tartar per deliquium4 ,on
 the other hand1 the mineral1 or fossil 
alkali1 is apt to lose its water in a   

dry atmosphere1 and then it is said to  
effloresce4 ,in this state it is often  
found on old walls4  ,volatile alkali is
 procured by burning animal substances2 
in ,egypt 7from whence1 as contained in 
sal ammoniac1 we till of late imported  
it7 from camel's dung2 but now from     
bones1 by distillation4 ,to the liquor  
thus procured they add vitriolic acid1  
or substances which contain it4 ,this   
acid unites with the alkali1 and common 
salt being put to it1 a double affinity 
takes place4 ,the vitriolic acid uniting
 with the mineral alkali of the salt1   
makes ,glauber salt1 and the marine acid
 uniting with the volatile alkali1 makes
 sal ammoniac4 ,slaked lime added to    
this1 unites with the marine acid of the
 ammoniac1 and sets loose the volatile  
alkali in the form of alkaline air1     
which combining with water1 makes the   
liquid caustic volatile alkali4 ,if     
chalk 7containing calcareous earth      
united with fixed air7 be mixed with the
 sal ammoniac1 heat will make the       

calcareous earth unite with the marine  
acid1 while the fixed air of the chalk  
will unite with the volatile alkali1 and
 assume a solid form1 being the sal     
volatile of the apothecaries4           
,,lecture ,,xvii4   ,of ,liquid         
,inflammable ,substances4  ,of liquid   
inflammable substances the principal is 
spirit of wine1 sometimes called ardent 
spirit1 and1 when highly rectified1     
alcohol4 ,it is obtained from vegetable 
substances by their going through the   
vinous fermentation4 ,it is considerably
 lighter than water1 colourless1 and    
transparent1 has a peculiar smell and   
taste1 and the property of inebriating4 
,ardent spirit seems to consist of a    
peculiar combination of phlogiston and  
water2 for when the vapour of it is made
 to pass through a red-hot earthen tube1
 it is resolved into water and          
inflammable air4 ,it is highly          
inflammable1 and burns without smoke1 or
 leaving any residuum2 and in the act of
 burning its phlogiston so unites with  

dephlogisticated air as to make fixed   
air4  ,ardent spirit mixes readily with 
water in all proportions1 and also with 
essential oils1 and balsams or resins1  
which are the same thing inspissated4   
,by its affinity with essential oils1   
ardent spirit extracts them froth       
aromatic plants2 and these liquors have 
obtained the name of tinctures4  ,when  
the tinctures are distilled1 the more   
volatile parts of the essential oils1   
which come over in distillation1 have   
acquired the name of waters2 as         
,lavender water1 ,rosemary water1 c4 and
 what remains in the still is called the
 extract of the plant4 ,if the tinctures
 be diluted with much water1 the        
resinous part of the plant will be      
obtained pure1 and separated from the   
extractive part1 which will remain      
dissolved in the water1 while the resin 
separates from it4  ,spirit of wine will
 not dissolve the gummy parts of        
vegetables2 and by this means the gummy 
substances may be separated from their  

solutions in water1 the spirit uniting  
with the water only4 ,on the other hand1
 if resins be dissolved in spirit of    
wine1 the affusion of water will        
separate them4 ,by means of the affinity
 of spirit of wine with water1 it will  
seize upon the water in which several   
salts are dissolved1 and thus produce an
 instant crystallization of them4  ,salt
 of tartar has a greater affinity to    
water than spirit of wine1 and by       
extracting water from it1 will assist in
 concentrating it2 but the best method  
of rendering spirit wine free from water
 is distillation1 the ardent spirit     
rising before the water4  ,spirit of    
wine mixed with the vitriolic and other 
mineral acids1 renders them milder1 and 
thereby more proper for certain         
medicinal uses4 ,this is called         
dulcifying them4  ,spirit of wine is a  
powerful antiseptic1 and is therefore of
 use to preserve vegetable and animal   
substances from putrefaction4   ,of     
,a,ether4  ,if spirit of wine be        

distilled with almost any of the acids1 
the produce is a liquor which has       
obtained the name of ,a,ether1 from its 
extreme lightness and volatility1 being 
much lighter1 and more volatile1 than   
any other fluid that we are acquainted  
with4 ,it is highly inflammable1 but the
 burning of it is accompanied with      
smoke1 and some soot2 and on this       
account it is a medium between spirit of
 wine and oil1 the acid having taken    
from the spirit of wine part of the     
water that was essential to it1 at the  
same time that it communicated something
 of its acid peculiarly modified2 since 
aethers have different properties       
according to the acids by which they are
 made2 as the vitriolic1 the nitrous1   
the marine1 and the acetous4 ,no aether1
 however1 can be made from the marine   
acid till it has been in some measure   
dephlogisticated2 from which it may be  
inferred1 that dephlogisticated air is  
necessary to the composition of aether4 
,vitriolic aether is the most common1 in

 consequence of the process by which it 
is made being the easiest4  ,a,ether    
does not mix with water in all          
proportions1 like spirit of wine1 but   
ten parts of water will take up one of  
aether4 ,it easily mixes with all oils4 
,it is something remarkable1 that though
 aether will not dissolve gold1 it will 
take from aqua regia the gold that has  
been previously dissolved in it4  ,by   
the quick evaporation of aether a       
considerable degree of cold may be      
procured2 and on this principle it has  
sometimes been applied to relieve the   
head-ach and other pains4     ,,lecture 
,,xviii4   ,of ,oil4  ,oil is a liquid  
inflammable substance1 of great         
tenacity1 disposed to pour in a stream  
rather than in drops4 ,it is little1 if 
at all1 soluble in water4 ,it burns with
 smoke and soot1 and leaves a residuum  
of a coaly substance4 ,it consists of   
acid and water combined with phlogiston4
  ,all oil is the produce of the        
vegetable or animal kingdom1 no proper  

mineral substance containing any of it4 
,by distillation oil is in part         
decomposed1 and by this means the       
thicker kinds of oil are rendered       
thinner and more volatile1 the acid1 to 
which their consistence is chiefly      
owing1 being lost in the process4 ,by   
repeated distillation it is supposed    
that all oils may be brought almost to  
the state of aether1 and even of ardent 
spirit4  ,acids act powerfully upon     
oils1 but very differently1 according to
 the nature of each4 ,alkalies also     
combine with oils1 and the less thin and
 volatile they are1 the more easily are 
they soluble in alkalies4 ,the union of 
alkali and oil makes soap4 ,all oil     
dissolves sulphur1 and with it makes    
what is called a balsam4 ,oils also     
dissolve metallic substances1 but most  
sensibly copper and lead4 ,united with  
the calx of lead1 it is used in         
painting4  ,oil not readily mixing with 
water1 it will diffuse itself over its  
surface1 and1 notwithstanding its       

tenacity1 it will do this very rapidly1 
and to a great extent2 and then it has  
the extraordinary effect of preventing  
the action of the wind upon the water1  
so as to prevent the forming of waves4  
,if a quantity of oil and water be put  
into a glass vessel and swung1 the      
surface of the water below the oil will 
be seen to change with respect to the   
vessel1 but not that of the oil4 ,if    
spirit of wine be put upon them1 that   
will be at rest1 and both the lower     
fluids in motion4  ,vegetable oil is of 
two kinds1 the soft1 or mild1 which has 
little or no taste or smell1 and the    
essential oil1 which is thin1 and       
retains the smell and taste of the plant
 from which it was extracted4  ,mild or 
sweet oil is expressed from the grains  
or kernels of vegetables1 and requires a
 considerable degree of heat to convert 
it into vapour1 in which state alone it 
is capable of being inflamed4           
,essential oil is volatile in the heat  
of boiling water1 and is generally      

obtained by means of distillation from  
the most odoriferous sorts of plants2   
but is sometimes found in their         
vesicles1 as in the rind of an orange4  
,the strong taste of this kind of oil   
arises from the disengaged acid which   
abounds in it2 and by this means it is  
soluble in spirit of wine1 which sweet  
oil is not2 but it loses much of this   
property by repeated distillations4 ,by 
long exposure to the air it loses its   
more volatile parts1 and thereby        
approaches to the nature of a resin4    
,this volatile odoriferous principle has
 been called the spiritus rector of the 
plant4  ,the essential oils of different
 plants differ much in their specific   
gravity1 and also in the manner by which
 they are affected by cold1 some being  
heavier and others lighter than water1  
and some being more difficultly1 and    
others more easily1 congealed4 ,though  
the differences with respect to weight  
and consistency in these oils is        
probably owing to the state of the acid 

that is combined with them1 these two   
properties are wholly independent of    
each other2 some essential oils being   
very thin and yet heavy1 and others     
thick and yet light4 ,essential oils are
 used in perfumes1 and also in medicine1
 acting powerfully the nervous system4  
,essential oils are very apt to be      
adulterated4 ,if it be with sweet oil1  
it may be discovered by evaporation on  
white paper1 or by a solution in spirit 
of wine1 which will not act upon the    
sweet oil4 ,if spirit of wine be mixed  
with it1 it will be discovered by a     
milky appearance upon putting water to  
it1 which uniting with the spirit1 will 
leave the oil much divided4 ,if oil of  
turpentine1 which is the cheapest of    
essential oils1 be mixed with any of the
 more valuable kinds1 it will be        
discovered by evaporation2 a strong     
smell of turpentine being left on the   
paper1 or cloth1 upon which the         
evaporation was made4  ,animal oil1 like
 the vegetable1 is of two kinds2 the    

first butter1 or fat1 which is easily   
congealed1 owing to the quantity of acid
 that is intimately combined with it4   
,it resembles the sweet oil of          
vegetables in having no smell or taste4 
,the other kind of animal oil is        
extracted by distillation from the      
flesh1 the tendons1 the bones1 and      
horns1 c4 of animals4 ,it differs       
essentially from the other kind of      
animal oil1 by containing an alkali     
instead of an acid4 ,by repeated        
distillation it becomes highly          
attenuated and volatile2 and in this    
state it is called the oil of ,dippel1  
the discoverer of it4  ,all oil exposed 
to much heat is in part decomposed1 and 
acquires a disagreeable smell2 and in   
this state it is said to be             
empyreumatic3 but this property is lost 
by repeated distillations4  ,besides the
 vegetable and animal oils above        
described1 there is a fossil oil called 
bitumen1 the several kinds of which     
differ much in colour and consistence2  

the most liquid is called petroleum1    
from being found in the cavities of     
rocks1 and the more solid kinds are     
amber1 jet1 asphaltum1 and pit-coal4    
,when distilled1 the principal component
 parts of all these substances are an   
oil and an acid4 ,but all fossil oil is 
probably of vegetable or animal origin1 
from masses of vegetables or animals    
long buried in the earth4 ,their        
differences from resins and other oily  
matters are probably owing to time2 the 
combinations of mineral acids and oils  
so nearly resembling bitumens1 the      
principal difference being their        
insolubility in spirit of wine4  ,that  
the most solid of these1 as amber1 has  
been formerly in a liquid state1 is     
evident1 from insects and other         
substances being frequently found in    
them2 and pit-coal has been often found 
with both the internal texture and      
external appearance of wood2 so that    
strata of pit-coal have probably been   
beds of peat in some former state of the

 earth4     ,,lecture ,,xix4   ,of      
,solid ,substances4  ,all solid         
substances are capable of becoming fluid
 by heat1 and most of them may thereby  
be reduced into a state of vapour1 or   
air2 and in passing from a fluid into a 
solid state their component parts assume
 a particular mode of arrangement1      
called crystallization1 which differs   
according to the nature of the          
substance2 so that all solids1          
especially if they be suffered to       
concrete slowly1 may be called crystals4
  ,exclusive of salts1 which have been  
considered already1 as formed by the    
union of acids and alkalis1 solids in   
general have obtained the names of      
earths1 or stones1 which differ only in 
their texture2 and they are             
distinguished into those that are       
metallizable1 or those that are not2 the
 former being called ores1 and the      
latter simply earths2 the principal of  
which are the calcareous1 siliceous1    
argillaceous1 magnesia1 terra ponderosa1

 and a few others which have been       
discovered lately1 but have not been    
much examined4   ,of ,calcareous ,earth4
  ,calcareous earth is found in the     
shells of fishes1 the bones of animals1 
chalk1 lime-stone1 marble1 and gypsum3  
but all calcareous earth is supposed to 
be of animal origin2 and beds of chalk1 
lime-stone1 or marble1 are thought to   
have been beds of shells formed in the  
sea1 in some pristine state of the      
earth4  ,the calcareous earth which is  
found in shells1 lime-stone1 and marble1
 is combined with fixed air1 discovered 
by effervescing with acids4 ,to obtain  
it perfectly pure1 the earth must be    
pounded and washed with water1 in order 
to free it from any saline substance    
which may be contained in it1 then      
dissolved in distilled vinegar1 and     
precipitated by mild alkalies4          
,lime-stone exposed to heat loses about 
half its weight1 in fixed air and water1
 and the remainder1 called quick-lime1  
attracts water very powerfully1 and     

their union is attended with much heat1 
after which it dissolves into a fine    
powder called slaked lime4 ,if it be    
left exposed to the atmosphere1 it will 
of itself1 by gradually imbibing        
moisture1 fall into the state of powder4
  ,water dissolves about one seven      
hundredth part of its weight of         
quick-lime1 and is then called          
lime-water4 ,exposed to the air1 a crust
 will be formed on its surface1 which is
 found to consist of calcareous earth   
and fixed air4  ,lime and water mixed   
with sand make mortar1 by which means   
different stones may be made to cohere  
as one mass1 which is the most valuable 
use of this kind of earth4  ,calcareous 
earth1 united with vitriolic acid1 makes
 gypsum2 and this substance pounded and 
exposed to heat1 parts with its water1  
and is then called plaister of ,paris4  
,in this state1 by imbibing water again1
 it becomes a firm substance1 and thus  
is useful in making moulds1 c4  ,the    
earth of animal bones is calcareous     

united to the phosphoric acid4   ,of    
,siliceous ,earth4  ,siliceous earth    
seems to be formed by nature from chalk1
 perhaps by the introduction of some    
unknown acid1 which the vitriolic acid  
is not able to dislodge4 ,it abounds in 
most substances which are hard enough to
 strike fire with steel1 as flint1 rock 
crystal1 and most precious stones4 ,it  
is not acted upon by any acid except the
 fluor and phosphoric1 but especially   
the former3 but it is soluble in        
alkalies2 and being then dissolved in   
water1 makes liquor silicum1 from which 
the purest siliceous earth may be       
precipitated by acids4 ,for this purpose
 about four times the weight of alkali  
must be made use of4 ,with about equal  
weights of alkali and siliceous sand is 
made glass1 of so great use in admitting
 light and excluding the weather from   
our houses1 as well as for making       
various useful utensils4 ,to make glass 
perfectly colourless1 and at the same   
time more dense1 commonly called flint  

glass1 manufacturers use a certain      
proportion of calx of lead and          
manganese4  ,siliceous earth is not     
affected by the strongest heat1 except  
by means of a burning lens1 or          
dephlogisticated air4     ,,lecture     
,,xx4   ,of ,argillaceous ,earth4       
,argillaceous earth is found in clay1   
schistus1 or slate1 and in mica2 but the
 purest is that which is precipitated   
from a solution of alum by alkalies2 for
 alum consists of the union of vitriolic
 acid and argillaceous earth4  ,this    
species of earth is ductile with water2 
it then hardens and contracts by heat1  
so as to be of the greatest use in      
forming bricks1 or stones of any        
required form or size4 ,by means of the 
property of clay to contract in the     
fire1 ,mr4 ,wedgwood has constructed an 
excellent thermometer to measure the    
degrees of extreme heat4  ,the ductility
 of clay seems to depend upon some acid1
 probably the vitriolic1 adhering to it2
 for it loses that property when it is  

burned into a brick1 but recovers it    
when it has been again dissolved in an  
acid4   ,of ,terra ,ponderosa4  ,terra  
ponderosa1 or marmor metallicum1 is     
generally found in two states1 viz4     
united to vitriolic acid1 when it is    
called calk1 or to fixed air1 when it is
 called terra ponderosa aerata4  ,to    
obtain it pure from its union with the  
vitriolic acid1 it must be melted with  
about twice its weight of fixed alkali2 
which unites with the acid1 and forming 
a saline substance1 may be washed out of
 it4 ,in this state it contains water1  
and therefore1 when exposed to heat1    
will yield fixed air2 whereas the terra 
ponderosa aerata will not yield fixed   
air by heat only1 but when steam is made
 to pass over it when red hot4 ,this    
proves that water is essential to the   
composition of fixed air4  ,this stone  
is distinguishable by its great specific
 gravity1 being four times as heavy as  
water2 but though in this it resembles  
an ore1 it has not been found to be     

metallizable4   ,of ,magnesia4  ,this   
species of earth is found in steatites1 
or soap rock1 ,spanish chalk1 asbestus1 
and ,muscovy talck2 but the purest is   
got by dissolving ,epsom salts 7which   
consists of this earth united to the    
vitriolic acid7 and precipitating it by 
a mild alkali4 ,in this state it becomes
 united to fixed air1 which may be      
expelled by heat4 ,it is then calcined1 
or caustic1 but differs from quick-lime 
by not being soluble in water4          
,asbestus1 which contains much of this  
kind of earth1 is remarkable for not    
being destructible by heat1 though it is
 sometimes found in flexible fibres1 so 
as to be capable of being woven into    
cloth4  ,muscovy talck is remarkable for
 the thin and transparent flakes into   
which it is divisible1 and thereby      
capable of various uses4  ,there are    
some other distinct species of earth1   
particularly one brought from ,botany   
,bay1 and another called ,stontiate1    
from the place where it was found in    

,scotland2 but they have not as yet been
 much examined4  ,all stones formed by  
nature are compounded1 and to           
distinguish them from one another1 and  
ascertain the parts of which they       
consist1 is the subject of lithology1 a 
very extensive branch of knowledge4     
,all the simple earths are nearly1 if   
not absolutely1 infusible2 but when they
 are mixed they may all be fused4       
,,lecture ,,xxi4   ,of ,ores4           
,metallizable earths1 commonly called   
ores1 when united to phlogiston1 make   
the metals1 distinguishable for their   
specific gravity1 their opacity1 shining
 appearance1 and fusibility4  ,all the  
proper metals are malleable1 and those  
which are not so are called semi-metals4
  ,the metals again are subdivided into 
the perfect and imperfect4 ,the former1 
which are gold1 silver1 and platina1    
suffer no change by fusion1 or the      
longest continued heat3 whereas heat    
calcines or dissipates the phlogiston of
 the imperfect metals1 which are        

mercury1 lead1 copper1 iron1 and tin1 so
 that they return to the state of earth2
 and this earth is always heavier than  
the metal1 though of less specific      
gravity1 having received an addition of 
weight from water or air3 but these     
earths1 or ores1 being exposed to heat  
in contact with substances containing   
phlogiston1 again become metals1 and are
 then said to be revived4  ,the         
semi-metals are bismuth1 zinc1 nickel1  
regulus of arsenic1 of cobalt1 of       
antimony1 of manganese1 of wolfram1 and 
of molybdena4  ,all metallic substances 
are crystallizable1 and each in a       
peculiar form1 which is discovered by   
leaving a hole in the bottom of the     
crucible in which they are melted1 and  
drawing out the stopper1 when the mass  
is beginning to lose its fluidity4      
,some of the metals will not unite to   
others when hot1 and others of them     
will2 and such as will unite with others
 are called solders4 ,thus tin is a     
solder for lead1 and brass1 gold1 or    

silver1 for iron4  ,ores are never found
 in regular strata1 like the different  
kinds of earth2 but in places which have
 formerly been cavities1 running in all 
directions1 with respect to the regular 
strata1 and commonly called veins4      
,many of the ores in their natural state
 are said to be mineralized with arsenic
 or sulphur1 those substances being     
intimately united with the metallic     
earths4  ,in order to convert the ores  
into metals1 some of them are first     
reduced to powder1 to wash out the      
earthy or saline particles4 ,they are   
then kept in a red heat1 which the      
workmen call roasting1 in order to drive
 away the arsenic1 or sulphur1 which are
 volatile2 and in the last place they   
are fused in contact with charcoal1 or  
other substances containing phlogiston2 
and to promote the fusion1 lime-stone is
 frequently mixed with them4 ,when the  
operation is completed1 the unmetallic  
parts are converted into glass1 or      
scoria1 which lies on the surface1      

whereas the metal is found at the       
bottom4  ,to discover the quantity of   
metal in a small piece of ore is called 
assaying4  ,when metals are fused       
together1 the specific gravity1         
fusibility1 and other properties are    
changed1 and in such a manner as could  
not be discovered from the properties of
 the constituent parts4   ,of ,gold4    
,gold is the heaviest of all metallic   
bodies except platina4 ,it appears      
yellow or reddish by reflected light1   
but green or blue by transmitted light1 
when it is reduced to thin plates4      
,though gold undergoes no change in a   
common furnace1 or burning lens1 it may1
 in part1 at least1 be calcined by the  
electric shock4  ,gold has the greatest 
ductility1 and in wires of equal        
diameters1 it has the greatest tenacity1
 of all the metals4 ,one grain of it may
 be made to cover #ef square inches2    
some gold leaf being less than a        
#bjj1jjjth part of an inch thick2 and   
when it is made to cover a silver wire1 

the gold upon it may not be more than   
one twelfth part of the thickness of the
 gold leaf4  ,this metal is soluble in  
aqua regia2 and being precipitated by a 
volatile alkali1 makes a powder called  
aurum fulminans1 which is one fourth    
heavier than the gold1 and explodes with
 great violence in a heat something     
greater than that of boiling water4     
,tin precipitates gold in the form of a 
purple powder1 called the powder of     
,cassius1 from the inventor of it1 and  
is used in enamels1 or the glassy       
coating which is given to metals by     
heat4  ,gold unites with most of the    
metals1 especially with mercury1 and    
these mixtures are called amalgams4 ,in 
gilding1 the amalgam is applied to the  
surface of the metal to be gilded1 and  
the mercury is driven off by heat1      
leaving the gold attached to the        
surface4  ,gold mixed with iron1 makes  
it harder1 for the purpose of cutting   
instruments4  ,to separate gold from the
 imperfect metals1 such as copper1 c4 it

 is mixed with lead1 and then exposed to
 a strong heat1 which calcines the lead1
 and with it the imperfect metals1      
leaving the gold pure4 ,this process is 
called cupellation1 from being performed
 in a small crucible called a cupell4   
,when the gold is mixed with silver1    
three parts more of silver are put to   
it1 and then the silver is dissolved by 
nitrous acid1 leaving the gold pure4    
,this process is called quartation1 from
 the gold being one fourth part of the  
mass4  ,the fineness of gold is         
generally estimated by dividing the gold
 into twenty-four parts1 called carats4 
,the phrase twenty-three carats fine    
means that the mass contains            
twenty-three parts out of twenty-four of
 pure gold1 the remainder being alloy1  
of some baser metal4 ,the fineness of   
gold may in some measure be discovered  
by the colour it leaves upon a          
touch-stone1 or fine-grained basaltes4  
,gold is generally found nearly pure1   
but mixed with earth1 or diffused in    

fine grains through stones4             
,,lecture ,,xxii4   ,of ,silver4        
,silver is the whitest of all the       
metals1 very ductile1 but less so than  
gold2 the thinnest leaves of it being   
one third thicker than those of gold4   
,it is not calcined in the heat of a    
common furnace1 but partially so by     
repeated fusion1 or a strong burning    
lens4  ,sulphureous fumes unite with    
silver1 and tinge it black4 ,the nitrous
 acid dissolves it1 and will hold more  
than half its weight of it in solution4 
,when fully saturated1 this solution    
deposits crystals1 which are called     
lunar nitre1 or nitre of silver4 ,when  
these crystals are melted1 and the water
 they contain driven off1 a black       
substance1 called lapis infernalis1 or  
lunar caustic1 is formed4 ,this is used 
as a cautery in surgery4 ,a strong heat 
will decompose this lunar nitre1 and    
recover the silver4  ,though the nitrous
 acid dissolves silver the most readily1
 the marine acid will deprive the       

nitrous of it1 and form a substance     
called luna cornea1 because1 when it is 
melted and cold1 it becomes a           
transparent mass something resembling   
horn4 ,from this luna cornea the purest 
silver may be obtained4 ,the vitriolic  
acid will likewise deprive the nitrous  
of the silver contained in it1 and form 
a white powder1 not easily soluble in   
water4  ,a fulminating silver may be    
made by the following process3 the      
silver must first be dissolved in pale  
nitrous acid1 then precipitated by      
lime-water1 dried1 and exposed to the   
air three days4 ,it must then be washed 
in caustic volatile alkali1 after which 
the fluid must be decanted1 and the     
black powder left to dry in the air4    
,the slightest friction will cause this 
powder to fulminate4 ,it is said1 that  
even a drop of water falling upon it    
will produce this effect2 so that it    
ought to be made only in very small     
quantities1 and managed with the        
greatest caution4  ,most of the metals  

precipitate silver4 ,that by mercury may
 be made to assume the form of a tree1  
called arbor ,dianae4  ,silver is found 
native in ,peru2 and the ores frequently
 contain sulphur1 or arsenic1 or both4  
,of ,platina4  ,platina is a metal      
lately discovered in the gold mines of  
,mexico1 where it is found in small     
particles1 never exceeding the size of a
 pea1 mixed with ferruginous sand and   
quartz4  ,the strongest fire will not   
melt these grains1 though it will make  
them cohere2 but they may be melted by a
 burning lens1 or a blow-pipe supplied  
with dephlogisticated air4  ,pure       
platina is the heaviest body in nature1 
its specific gravity exceeding          
twenty-two4 ,it is very malleable1      
though considerably harder than gold or 
silver1 and has the property of welding 
in common with iron4 ,this metal is not 
affected by exposure to the air1 or by  
any simple acid1 though concentrated and
 hot2 but it is dissolved by            
dephlogisticated marine acid1 and by    

aqua regia1 in which a little nitrous   
air is procured4 ,the solution is brown1
 and when diluted yellow4 ,this liquor  
is very corrosive1 and tinges animal    
substances of a blackish brown colour4  
,platina is precipitated from a solution
 in aqua regia by sal-ammoniac1 as gold 
is by martial vitriol4 ,iron is         
precipitated from this solution by the  
,prussian alkali4 ,also most of the     
metals precipitate platina1 but not in  
its metallic state4  ,arsenic           
facilitates the solution of platina2 and
 by melting it with equal parts of      
arsenic and vegetable alkali1 and then  
reducing the mass to a powder1 it may be
 made to take any form2 and a strong    
heat will dissipate the arsenic and the 
alkali1 leaving the platina in the shape
 required1 not fusible by any heat in a 
common furnace4  ,platina does not      
readily combine with gold or silver1 and
 it resists the action of mercury as    
much as iron2 but it mixes well with    
lead1 making it less ductile1 and even  

brittle1 according to the proportion of 
the platina4 ,with copper it forms a    
compound which takes a beautiful polish1
 not liable to tarnish1 and is therefore
 used with advantage for mirrors of     
reflecting telescopes4 ,it unites easily
 with tin1 and also with bismuth1       
antimony1 and zinc4     ,,lecture       
,,xxiii4   ,of ,mercury4  ,mercury is   
the most fusible of all the metals1 not 
becoming solid but in #dj deg4 below #j 
in ,fahrenheit's thermometer4 ,it is    
then malleable4 ,it is heavier than any 
other metal except gold or platina4 ,it 
is volatile in a temperature much lower 
than that of boiling water1 and in vacuo
 in the common temperature of the       
atmosphere2 and at six hundred it boils4
  ,in a degree of heat in which it would
 rise easily in vapour1 mercury imbibes 
pure air1 and becomes a red calx1 called
 precipitate per se4 ,at a greater      
degree of heat it parts with that air1  
and is running mercury again4  ,mercury 
is not perceptibly altered by exposure  

to the air4  ,mercury is acted upon by  
the vitriolic acid when hot4 ,in this   
process vitriolic acid air is procured1 
and the mercury is converted into a     
white substance1 which being dipped in  
water becomes yellow1 called turbith    
mineral1 one third heavier than the     
mercury from which it was made4 ,by heat
 this substance parts with its pure air1
 and becomes running mercury2 but if the
 process be made in a clean earthen     
vessel1 there will remain a portion of  
red calx1 which cannot be reduced by any
 degree of heat1 except in contact with 
some substance containing phlogiston4   
,if this be done with a burning lens1 in
 inflammable air1 much of the air will  
be absorbed4  ,mercury is dissolved most
 readily in the nitrous acid1 when the  
purest nitrous air is procured2 and     
there remains a substance which is first
 yellow1 and by continuance red1 called 
red precipitate4 ,in a greater degree of
 heat the dephlogisticated air will be  
recovered1 and the mercury be revived2  

but the substance yields nitrous air    
after it becomes solid1 and till it     
changes from yellow to red4  ,the       
precipitates of mercury from acids by   
means of alkalies possess the property  
of exploding1 when they are exposed to a
 gradual heat in an iron spoon1 after   
having been triturated with one sixth of
 their weight of the flowers of sulphur4
 ,the residuum consists of a            
violet-coloured powder1 which1 by       
sublimation1 is converted into cinnabar4
  ,it seems1 therefore1 as if the       
sulphur combined suddenly with the      
mercury1 and expelled the               
dephlogisticated air in an elastic      
state4  ,the marine acid seizes upon    
mercury dissolved in nitrous acid1 and  
if the acid be dephlogisticated1 the    
precipitate is corrosive sublimate2 but 
with common marine acid1 it is called   
calomel1 or mercurius dulcis4 ,this     
preparation is generally made in the dry
 way1 by triturating equal parts of     
mercury1 common salt and vitriol1 and   

exposing the whole to a moderate heat2  
when the corrosive sublimate rises1 and 
adheres to the upper part of the glass  
vessel in which the process is made4    
,mercury combines readily with sulphur  
by trituration1 and with it forms a     
black powder called ,ethiops mineral4 ,a
 more intimate combination of mercury   
and sulphur is made by means of fire4   
,this is called cinnabar1 about one     
third of which is sulphur4 ,vermillion  
is cinnabar reduced to powder4  ,mercury
 readily unites with oil1 and with it   
forms a deep black or blue compound1    
used in medicine4  ,it readily combines 
with most of the metals1 and when it is 
used in a sufficient quantity to make   
them soft1 the mixture is called an     
amalgam4 ,it combines most readily with 
gold1 silver1 lead1 tin1 bismuth1 and   
zinc4 ,looking-glasses are covered on   
the back with an amalgam of mercury and 
tin4  ,when mercury is united with lead 
or other metals1 it is rendered less    
brilliant and less fluid2 but agitation 

in pure air converts the impure metal   
into a calx1 together with much of the  
mercury1 in the form of a black powder4 
,heat recovers the pure air1 and the    
mercury1 leaving the calx of the impure 
metal4  ,much mercury is found native in
 a slaty kind of earth1 or in masses of 
clay or stone2 but the greatest quantity
 is found combined with sulphur in      
native cinnabar4     ,,lecture ,,xxiv4  
,of ,lead4  ,lead is a metal of a bluish
 tinge1 of no great tenacity1 but very  
considerable specific gravity1 being    
heavier than silver4 ,it melts long     
before it is red hot1 and is then       
calcined1 if it be in contact with      
respirable air4 ,when boiling it emits  
fumes1 and calcines very rapidly4 ,it   
may be granulated by being poured into a
 wooden box1 and agitated4 ,during      
congelation it is brittle1 so that the  
parts will separate by the stroke of a  
hammer2 and by this means the form of   
its crystals may be discovered4  ,in the
 progress of calcination it first       

becomes a dusky grey powder1 then       
yellow1 when it is called massicot2     
then1 by imbibing pure air1 it becomes  
red1 and is called minium1 or red lead4 
,in a greater degree of heat it becomes 
massicot again1 having parted with its  
pure air4 ,if the heat be too great1 and
 applied rapidly1 it becomes a flaky    
substance1 called litharge2 and with    
more heat it becomes a glass1 which     
readily unites with metallic calces and 
earths1 and is a principal ingredient in
 the manufacture of flint glass1 giving 
it its peculiar density and refractive  
power4  ,though lead soon tarnishes1 the
 imperfect calx thus made does not      
separate from the rest of the metal1 and
 therefore protects it from any farther 
action of the air1 by which means it is 
very useful for the covering of houses1 
and other similar purposes4 ,all acids  
act upon lead1 and form with it         
different saline substances4 ,white-lead
 consists of its union with vinegar and 
pure air4 ,also dissolved in vinegar1   

and crystallized1 it becomes sugar of   
lead1 which1 like all the other         
preparations of this metal1 is a deadly 
poison4  ,oils dissolve the calces of   
lead1 which1 by this means1 is the basis
 of paints1 plaisters1 c4  ,by means of 
heat litharge decomposes common salt1   
the lead uniting with the marine acid1  
and forming a yellow substance1 used in 
painting1 and by this means the fossil  
alkali is separated4  ,lead unites with 
most metals1 though not with iron4 ,two 
parts of lead and one of tin make a     
solder1 which melts with less heat than 
either of the metals separately2 but a  
composition of eight parts of bismuth1  
five of lead1 and three of tin1 makes a 
metal which melts in boiling water4     
,this metal will be dissolved by water  
if it contain any saline matter1 and the
 drinking of it occasions a peculiar    
kind of cholic4  ,lead is sometimes     
found native1 but generally minerally   
mineralized with sulphur or arsenic1 and
 often mixed with a small quantity of   

silver4   ,of ,copper4  ,copper is a    
metal of a reddish or brownish colour1  
considerably sonorous1 and very         
malleable4  ,at a heat far below        
ignition1 the surface1 of copper becomes
 covered with a range of prismatic      
colours1 the commencement of its        
calcination2 and with more heat a black 
scale is formed1 which easily separates 
from the metal1 and in a strong heat it 
melts1 and burns with a bluish green    
flame4  ,copper rusts by exposure to the
 air2 but the partially-calcined surface
 adheres to the metal1 as in the case of
 lead1 and thus preserves it from       
farther corrosion4  ,copper dissolved in
 the vitriolic acid forms crystals of a 
blot colour1 called blue copperas4 ,from
 this solution it is precipitated by    
iron1 which by this means becomes coated
 with copper4 ,the nitrous acid         
dissolves copper with most rapidity1    
producing nitrous air4 ,if the solution 
be distilled1 almost all the acid will  
be retained in the residuum1 which is   

white2 but more heat will expel the     
acid1 chiefly in the form of            
dephlogisticated air1 and the remainder 
will be a black substance1 consisting of
 the pure calx of copper4 ,the vegetable
 acids dissolve copper as well as the   
mineral ones1 which makes the use of    
this metal for culinary purposes in some
 cases dangerous4 ,to prevent this they 
give it a coat of tin4 ,the solution of 
copper in the vegetable acid is called  
verdigris4  ,alkalies dissolve copper as
 well as acids4 ,with the volatile      
alkali a blue liquor is formed1 but in  
some cases it becomes colourless4 ,all  
the circumstances of this change of     
colour have not yet been examined4 ,both
 oil and sulphur will dissolve copper1  
and with the latter it forms a blackish 
grey compound1 used by dyers4  ,copper  
readily unites with melted tin1 at a    
temperature much lower than that which  
is necessary to melt the copper2 by     
which means copper vessels are easily   
covered with a coating of tin4 ,a       

mixture of copper and tin1 called       
bronze1 the specific gravity of which is
 greater than that of the medium of the 
two metals1 is used in casting statues1 
cannon1 and bells2 and in a certain     
proportion this mixture is excellent for
 the purpose of mirrors of reflecting   
telescopes1 receiving a fine polish1 and
 not being apt to tarnish4 ,copper and  
arsenic make a brittle compound called  
tombach2 and with zinc it makes the     
useful compound commonly called brass1  
in which zinc is about one third of its 
weight4  ,copper is sometimes found     
native2 but commonly mixed with sulphur1
 in ores of a red1 green1 or blue       
colour4  ,copper being an earlier       
discovery than that of iron1 was        
formerly used for weapons and the       
shoeing of horses2 and the ancients had 
a method1 with which we are not well    
acquainted1 of giving it a considerable 
degree of hardness1 so that a sword made
 of it might have a pretty good edge4   
,,lecture ,,xxv4   ,of ,iron4  ,iron is 

a metal of a bluish colour1 of the      
greatest hardness1 the most variable in 
its properties1 and the most useful of  
all the metals2 so that without it it is
 hardly possible for any people to make 
great advances in arts and civilization4
  ,this metal readily parts with its    
phlogiston1 so as to be very subject to 
calcine1 or rust1 by exposure to the    
air4 ,the same is evident by the colours
 which appear on its surface when       
exposed to heat1 and also when it is    
struck with flint2 the particles that   
fly from it being iron partially        
calcined4 ,in consequence of its readily
 parting with its phlogiston1 it is     
capable of burning1 like wood or other  
fuel1 in pure air4  ,iron and platina   
have the property of welding when very  
hot1 so that two pieces may be joined   
without any solder4  ,when iron is      
heated in contact with steam1 part of   
the water takes the place of the        
phlogiston1 while the rest unites with  
it1 and makes inflammable air4 ,by this 

means the iron acquires one third more  
weight1 and becomes what is called      
finery cinder4 ,this substance1 heated  
in inflammable air1 imbibes it1 parts   
with its water1 and becomes perfect iron
 again4 ,if the iron be heated in pure  
air1 it also imbibes the water1 of which
 that air chiefly consists1 and also a  
portion of the peculiar element of the  
pure air4  ,the solution of iron in     
spirit of vitriol produces green        
copperas2 which being calcined1 becomes 
a red substance1 called colcothar4  ,the
 precipitate of iron1 by an infusion of 
galls1 is the colouring matter in ink1  
which is kept suspended by means of gum4
 ,the precipitate from the same solution
 by phlogisticated alkali1 is ,prussian 
blue4  ,water saturated with fixed air  
dissolves iron1 and makes a pleasant    
chalybeat4  ,the calx of iron gives a   
green colour to glass4  ,iron readily   
combines with sulphur4 ,when they are   
found combined by nature1 the substance 
is called pyrites4  ,the union of       

phosphoric acid with iron makes it      
brittle when cold1 commonly called cold 
short2 and the union of arsenic makes it
 brittle when hot1 thence called red    
short4  ,iron unites with gold1 silver1 
and platina1 and plunged in a white heat
 into mercury1 it becomes coated with   
it2 and if the process be frequently    
repeated1 it will become brittle1 which 
shews that there is some mutual action  
between them4  ,iron readily unites with
 tin2 and by dipping thin plates of iron
 into melted tin1 they get a complete   
coating of it1 and make the tinned      
plates in common use4  ,when crude iron 
comes from the smelting furnace it is   
brittle2 and when it is white within1 it
 is extremely hard2 but when it has a   
black grain1 owing to its having more   
phlogiston1 it is softer1 and may be    
filed and bored4  ,cast iron becomes    
malleable by being exposed to a blast of
 air when nearly melting2 the           
consequence of which is a discharge of  
inflammable air1 and the separation of a

 liquid substance1 which1 when          
concreted1 is called finery cinder4 ,the
 iron generally loses one fourth of its 
weight in the process4 ,crude iron      
contains much plumbago1 and the access  
of pure air probably assists in         
discharging it1 by converting it into   
air1 chiefly inflammable4  ,malleable   
iron1 exposed to a red heat in contact  
with charcoal1 called cementation1      
converts it into steel1 which has the   
properties of becoming much harder than 
iron1 and very elastic1 by being first  
made very hot1 and then suddenly cooled1
 by plunging it in cold water4 ,by first
 making it very hard1 and then giving   
different degrees of heat1 and cooling  
it in those different degrees1 it is    
capable of a great variety of tempers1  
proper for different uses4 ,of the      
degrees of heat workmen judge by the    
change of colour on its surface4 ,steel1
 like crude iron1 is capable of being   
melted without losing its properties4   
,it is then called cast steel1 and is of

 a more uniform texture4 ,iron acquires 
some little weight by being converted   
into steel2 and when dissolved in acid1 
it yields more plumbago4 ,steel has     
something less specific gravity than    
iron4 ,if the cementation be continued  
too long1 the steel acquires a darkish  
fracture1 it is more fusible1 and       
incapable of welding4 ,steel heated in  
contact with earthy matters1 is reduced 
to iron4  ,iron is the only substance   
capable of magnetism2 and hardened steel
 alone is capable of retaining          
magnetism4 ,the loadstone is an ore of  
iron4     ,,lecture ,,xxvi4   ,of ,tin4 
,tin is a metal of a slightly yellowish 
cast1 though harder than lead1 very     
malleable1 but of no great tenacity2 so 
that wires cannot be made of it4 ,it    
easily extends under the hammer1 and    
plates of it1 called tinfoil1 are made  
only one thousandth part of an inch     
thick1 and might be made as thin again4 
,tin has less specific gravity than any 
other metal4 ,it melts long before      

ignition1 at #daj of ,fahrenheit1 and by
 the continuance of heat is slowly      
converted into a white powder1 which is 
the chief ingredient in putty1 used in  
polishing1 c4 ,like lead1 it is brittle 
when heated little short of fusion1 and 
may be reduced into grains by agitation 
as it passes from a fluid to a solid    
state4  ,the calx of tin resists fusion 
more than that of any other metal1 which
 makes it useful in making an opaque    
white enamel4  ,tin loses its bright    
surface when exposed to the air1 but is 
not properly subject to rust2 so that it
 is useful in protecting iron and other 
metals from the effects of the          
atmosphere4  ,concentrated vitriolic    
acid1 assisted by heat1 dissolves half  
its weight of tin1 and yields vitriolic 
acid air4 ,with more water it yields    
inflammable air4 ,during the solution   
the phlogiston of the tin uniting with  
the acid1 forms sulphur1 which makes it 
turbid4 ,by long standing1 or the       
addition of water1 the calx of tin is   

precipitated from the solution4 ,the    
nitrous acid dissolves tin very rapidly 
without heat1 and yields but little     
nitrous air4 ,with marine acid this     
metal yields inflammable air4 ,with aqua
 regia it assumes the form of a         
gelatinous substance used by dyers to   
heighten the colour of some red         
tinctures1 so as to produce a bright    
scarlet in dying wool4  ,a transparent  
liquor1 which emits very copious fumes1 
called1 from the inventor1 the smoking  
liquor of ,libavius1 is made by         
distilling equal parts of amalgam of tin
 and mercury with corrosive sublimate1  
triturated together4 ,a colourless      
liquor comes over first1 and then a     
thick white fume1 which condenses into  
the transparent liquor above mentioned4 
,mr4 ,adet has shewn1 that this liquor  
bears the same relation to the common   
solution of tin1 that corrosive         
sublimate does to calomel1 and has given
 an ingenious solution of many of its   
properties4  ,tin detonates with nitre2 

and if the crystals made by the solution
 of copper in the nitrous acid be       
inclosed in tinfoil1 nitrous fumes will 
be emitted1 and the whole will become   
red hot4 ,also if five times its weight 
of sulphur be added to melted tin1 a    
black brittle compound1 which readily   
takes fire1 will be formed4  ,another   
combination of tin1 sulphur1 and        
mercury1 makes a light yellow substance 
called aurum musivum used in painting4  
,tin is the principal ingredient in the 
composition of pewter1 the other        
ingredients being lead1 zinc1 bismuth1  
and copper2 each pewterer having his    
peculiar receipt4 ,it is also used in   
coating copper and iron plates1 and in  
silvering looking-glasses1 besides being
 cast into a variety of forms1 when it  
is called block tin4  ,tin is sometimes 
found native1 but is generally          
mineralized with sulphur and arsenic4   
,the latter is thought to be always     
contained in tin1 and to be the cause of
 the crackling noise made by bending    

plates of it4   ,of the ,semi-metals4   
,bismuth is a semi-metal of a yellowish 
or reddish cast1 but little subject to  
change in the air2 harder than lead1 but
 easily broken1 and reducible to powder4
 ,when broken it exhibits large shining 
facets1 in a variety of positions4 ,thin
 pieces of it are considerably sonorous4
  ,bismuth melts at about #dfj deg4 of  
,fahrenheit4 ,with more heat it ignites1
 and burns with a slight blue flame1    
while a yellowish calx1 called flowers  
of bismuth1 is produced4 ,with more heat
 it becomes a greenish glass4 ,in a     
strong heat1 and in close vessels1 this 
metal sublimes4  ,vitriolic acid1 even  
concentrated and boiling1 has but little
 effect upon bismuth2 but the nitrous   
acid acts upon it with the greatest     
rapidity and violence1 producing much   
nitrous air1 mixed with phlogisticated  
nitrous vapour4 ,from the solution of   
bismuth in this acid1 a white substance1
 called magistery of bismuth1 is        
precipitated by the affusion of water4  

,this has been used as a paint for the  
skin but has been thought to injure it4 
,the marine acid does not readily act   
upon bismuth2 but when concentrated1 it 
forms with it a saline combination1     
which does not easily crystallize1 but  
may be sublimed in the form of a soft   
fusible salt1 called butter of bismuth4 
,bismuth unites with most metallic      
substances1 and in general renders them 
more fusible4 ,when calcined with the   
imperfect metals1 it unites with them1  
and has the same effect as lead in      
cupellation4  ,bismuth is used in the   
composition of pewter1 in printers'     
types1 and other metallic mixtures4     
,this metal is sometimes found native1  
but more commonly mineralized with      
sulphur4     ,,lecture ,,xxvii4   ,of   
,nickel4  ,nickel is a semi-metal of a  
reddish cast1 of great hardness1 and    
always magnetical2 on which account it  
is supposed to contain iron1 though     
chemists have not yet been able to      
separate them4  ,the purest nickel was  

so infusible as not to run into a mass  
in the strongest heat of a smith's      
forge2 but then it was in some degree   
malleable4  ,concentrated acid of       
vitriol only corrodes nickel4 ,alkalies 
precipitate it from its solution in the 
nitrous acid1 and dissolve the          
precipitate4 ,it readily unites with    
sulphur4  ,nickel is found either native
 or mineralized with several other      
metals1 especially with copper1 when it 
is called kupfer nickel1 or false       
copper1 being of a reddish or copper    
colour4  ,this semi-metal has not yet   
been applied to any use4   ,of ,arsenic4
  ,what is commonly called arsenic is   
the calx of a semi-metal called the     
regulus of arsenic4 ,it is a white and  
brittle substance1 expelled from the    
ores of several metals by heat4 ,it is  
then refined by a second sublimation1   
and melted into the masses in which it  
is commonly sold4 ,this calx is soluble 
in about eighty times its weight of cold
 water1 or in fifteen times its weight  

of boiling water4 ,it acts in many      
respects like an acid1 as it decomposes 
nitre by distillation1 when the nitrous 
acid flies off1 and the arsenical salt  
of ,macquer remains behind4  ,when the  
calx of arsenic is distilled with       
sulphur1 the vitriolic acid flies off1  
and a substance of a yellow colour1     
called orpiment1 is produced4 ,this     
appears to consist of sulphur and the   
regulus of arsenic2 part of the sulphur 
receiving pure air from the calx1 to    
which it communicates phlogiston2 and   
thus the sulphur becomes converted into 
vitriolic acid1 while the arsenical calx
 is reduced1 and combines with the rest 
of the sulphur4  ,the combination of    
sulphur and arsenic1 by melting them    
together1 is of a red colour1 known by  
the name of realgal1 or realgar4 ,it is 
less volatile than orpiment4  ,the      
solution of fixed alkali dissolves the  
calx of arsenic1 and by means of heat a 
brown tenacious mass is produced1 and   
having also a disagreeable smell1 it is 

called liver of arsenic4  ,the regulus  
of arsenic is of a yellow colour1       
subject to tarnish or grow black1 by    
exposure to the air1 very brittle1 and  
of a laminated texture4 ,in close       
vessels it wholly sublimes1 but burns   
with a small flame in pure air4         
,vitriolic acid has little action upon  
this semi-metal1 except when hot2 but   
the nitrous acid acts readily upon it1  
and likewise dissolves the calx1 as does
 boiling marine acid1 though it affects 
it very little when cold4  ,most of the 
metals unite with the regulus of        
arsenic4  ,dephlogisticated marine acid 
converts the calx of arsenic into       
arsenical acid by giving it pure air4   
,the acid of arsenic acts more or less  
upon all metals1 but the phenomena do   
not appear to be of much importance4    
,the calx of acid is used in a variety  
of the arts1 especially in the          
manufactory of glass4 ,orpiment and     
realgar are used as pigments4 ,some     
attempts have been made to introduce it 

into medicine1 but being dangerous1 the 
experiments should be made with caution4
   ,of ,cobalt4  ,cobalt is a semi-metal
 of a grey or steel colour1 of a        
close-grained fracture1 more difficult  
of fusion than copper1 not easily       
calcined4 ,it soon tarnishes in the air1
 but water has no effect upon it4       
,cobalt1 dissolved in aqua regia1 makes 
an excellent sympathetic ink1 appearing 
green when held to the fire1 and        
disappearing when cold1 unless it has   
been heated too much1 when it burns the 
paper4  ,the calx of cobalt is of a deep
 blue colour1 which1 when fused1 makes  
the blue glass called smalt4 ,the ore of
 cobalt1 called zaffre1 is found in     
several parts of ,europe1 but chiefly in
 ,saxony4 ,as it is commonly sold1 it   
contains twice or thrice its weight of  
powder of flints4 ,the smalt is usually 
composed of one part of calcined cobalt1
 fused with two parts of powder of flint
 and one of pot-ash4  ,the chief use of 
cobalt is for making smalt2 but the     

powder and the blue-stone used by       
laundresses is a preparation made by the
 ,dutch of a coarse kind of smalt4   ,of
 ,zinc4  ,zinc is a semi-metal of a     
bluish cast1 brighter than lead1 and so 
far malleable as not to be broken by a  
hammer1 though it cannot be much        
extended4 ,when broken by bending1 it   
appears to consist of cubical grains4   
,if it be heated nearly to melting1 it  
will be sufficiently brittle to be      
pulverized4 ,it melts long before       
ignition1 and when it is red hot1 it    
burns with a dazzling white flame1 and  
is calcined with such rapidity1 that its
 calx flies up in the form of white     
flowers1 called flowers of zinc1 or     
philosophical wool4 ,in a stronger heat 
they become a clear yellow glass4       
,heated in close vessels1 this metal    
rises without decomposition1 being the  
most volatile of all the metals except  
the regulus of arsenic4  ,zinc dissolved
 in diluted vitriolic acid1 yields much 
inflammable air1 and has a residuum1    

which appears to be plumbago1 and the   
liquor forms crystals1 called white     
copperas4 ,this metals also yields      
inflammable air when dissolved in the   
marine acid4 ,dissolved in the nitrous  
acid1 it yields dephlogisticated nitrous
 air1 with very little proper nitrous   
air4  ,the ore of zinc1 called calamine1
 is generally of a white colour2 and the
 chief use of it is to unite it with    
copper1 with which it makes brass and   
other gold-coloured mixtures of metals4 
,the calx and the salts of this metal   
are occasionally used in medicine4      
,,lecture ,,xxviii4   ,of ,antimony4    
,the regulus of antimony is of a silvery
 white colour1 of a scaly texture1 very 
brittle1 and melts soon after ignition4 
,by continuance of heat it calcines in  
white fumes1 called argentine flowers of
 antimony1 which melt into a hyacinthine
 glass4 ,in close vessels it rises      
without decomposition4 ,its calx is     
soluble in water1 like that of arsenic4 
,this metal tarnishes1 but does not     

properly rust1 by exposure to the air4  
,this metal is soluble in aqua regia4   
,it detonates with nitre1 and what      
remains of equal parts of nitre and     
regulus of antimony after detonation1 in
 a hot crucible1 is called diaphoretic  
antimony4 ,the water used in this       
preparation contains a portion of the   
calx suspended by the alkali1 and being 
precipitated by an acid1 is called      
ceruse of antimony4  ,when regulus of   
antimony is pulverized and mixed with   
twice its weight of corrosive sublimate 
7which is attended with heat7 and then  
distilled with a gentle fire1 a thick   
fluid comes over1 which is congealed in 
the receiver1 or in the neck of the     
retort1 and is called butter of         
antimony4 ,the residuum consists of     
revived mercury1 with some regulus and  
calx of antimony4 ,when this butter of  
antimony is thrown into pure water1     
there is a white precipitate1 called    
powder of algaroth1 a violent emetic4   
,nitrous acid dissolves the butter of   

antimony2 and when an equal weight of   
nitrous acid has been three times       
distilled to dryness from butter of     
antimony1 the residuum1 after ignition1 
is called bezoar mineral1 and seems to  
be little more than a calx of the metal4
  ,crude antimony1 which has been much  
used in the experiments of alchemists1  
is a combination of sulphur and regulus 
of antimony4 ,heat melts it1 and finally
 converts it into glass1 of a dark red  
colour1 called liver of antimony4 ,if   
antimony be melted or boiled with a     
fixed alkali1 a precipitate is made by  
cooling1 called kermes mineral1 formerly
 used in medicine4 ,the antimonial      
preparations that are now most in use   
are antimonial wine and tartar emetic4  
,the wine is made by infusing pulverized
 glass of antimony in ,spanish wine some
 days1 and filtering the clear fluid    
through paper4 ,the emetic tartar1 or   
antimonial tartar1 is a saline          
substance1 composed of acid of tartar1  
vegetable alkali1 and antimony partially

 calcined4 ,the preparation may be seen 
in the ,dispensaries4  ,the regulus of  
antimony is used in the form of pills1  
which purge more or less in proportion  
to the acid they meet with2 and as they 
undergo little or no change in passing  
through the body1 they are called       
perpetual pills4   ,of ,manganese4      
,manganese is a hard1 black mineral1    
very ponderous1 and the regulus of it is
 a semi-metal of a dull white colour    
when broken1 but soon grows dark by     
exposure to the air4 ,it is hard and    
brittle1 though not pulverizable1 rough 
in its fracture1 and of very difficult  
fusion4 ,its calces are white when      
imperfect1 but black1 or dark green1    
when perfect4 ,the white calx is soluble
 in acids4 ,when broken in pieces1 it   
falls into powder by a spontaneous      
calcination1 and this powder is         
magnetical1 though the mass was not     
possessed of that property4 ,the black  
calx of manganese is altogether         
insoluble in acids4 ,it contains much   

dephlogisticated air4  ,the calx of     
manganese is used in making glass2 the  
glass destroying the colour of that of  
the other materials1 and thereby making 
the whole mass transparent4  ,this      
semi-metal mixes with most of the metals
 in fusion1 but not with mercury4       
,there is another ore of manganese1     
called black woad1 which inflames       
spontaneously when mixed with oil4   ,of
 ,wolfram4  ,wolfram is a mineral of a  
brownish or black colour1 found in the  
tin mines of ,cornwall1 of a radiated or
 foliated texture1 shining almost like a
 metal4 ,it contains much of the calx of
 manganese1 and iron2 but when the      
substance is pulverized1 these are      
easily dissolved1 and the calx of       
wolfram is found to be yellow4  ,this   
calx turns blue by exposure to light2   
and an hundred grains of it heated with 
charcoal will yield sixty grains of a   
peculiar metal1 in small particles1     
which1 when broken1 look like steel4 ,it
 is soluble in the vitriolic or marine  

acids1 and reduced to a yellow calx by  
nitrous acid or aqua regia4   ,of       
,molybdena4  ,molybdena is a substance  
which much resembles plumbago2 but its  
texture is scaly1 and not easily        
pulverized1 on account of a degree of   
flexibility which its laminae possess4  
,with extreme heat1 and mixed with      
charcoal1 it yields small particles of a
 metal that is grey1 brittle1 and       
extremely infusible2 and uniting with   
several of the metals1 it forms with    
them brittle or friable compounds4 ,by  
heat it is converted into a white calx4 
,of ,solid ,combustible ,substances4    
,there yet remains a class of solid     
substances1 of the combustible kind1 but
 most of them have been already         
considered under the form of the fluids1
 from which they are originally formed1 
as bitumen1 pit-coal1 and amber2 or     
under the principal ingredients of which
 they are composed1 as sulphur and      
plumbago4  ,there only remains to be    
mentioned the diamond1 which is of a    

nature quite different from that of the 
other precious stones1 the principal    
ingredient in which is siliceous earth1 
which renders them not liable to be much
 affected by heat4 ,on the contrary1 the
 diamond is a combustible substance2 for
 in a degree of heat somewhat greater   
than that which will melt silver1 it    
burns with a slight flame1 diminishes   
common air1 and leaves a soot behind4   
,also1 if diamond powder be triturated  
with vitriolic acid1 it turns it black1 
which is another proof of its containing
 phlogiston4  ,the diamond is valued on 
account of its extreme hardness1 the    
exquisite polish it is capable of1 and  
its extraordinary refractive power2 for 
light falling on its interior surface   
with an angle of incidence greater than 
#bd-a_/b will be wholly reflected1      
whereas in glass it requires an angle of
 #da degrees4     ,,lecture ,,xxix4     
,of the ,doctrine of ,phlogiston and the
 ,composition of ,water4  ,it was       
supposed to be a great discovery of ,mr4

 ,stahl1 that all inflammable           
substances1 as well as metals1 contain a
 principle1 or substance1 to which he   
gave the name of phlogiston1 and that   
the addition or deprivation of this     
substance makes some of the most        
remarkable changes in bodies1 especially
 that the union of a metallic calx and  
this substance makes a metal2 and that  
combustion consists in the separation of
 phlogiston from the substances that    
contain it4 ,that it is the same        
principle1 or substance1 that enters    
into all inflammable substances1 and    
metals1 is evident1 from its being      
disengaged from any of them1 and        
entering into the composition of any of 
the others4 ,thus the phlogiston of     
charcoal or inflammable air becomes the 
phlogiston of any of the metals1 when   
the calx is heated in contact with      
either of them4  ,on the contrary1 ,mr4 
,lavoisier and most of the ,french      
chemists1 are of opinion1 that there is 
no such principle1 or substance1 as     

phlogiston2 that metals and other       
inflammable bodies are simple           
substances1 which have an affinity to   
pure air2 and that combustion consists  
not in the separation of any thing from 
the inflammable substance1 but in the   
union of pure air with it4  ,they       
moreover say1 that water is not1 as has 
been commonly supposed1 a simple        
substance1 but that it consists of two  
elements1 viz4 pure air1 or oxygene1 and
 another1 to which they give the name of
 hydrogene1 which1 with the principle of
 heat1 called by them calorique1 is     
inflammable air4  ,the principal fact   
adduced by them to prove that metals do 
not lose any thing when they become     
calces1 but only gain something1 is1    
that mercury becomes a calx1 called     
precipitate per se1 by imbibing pure    
air1 and that it becomes running mercury
 again by parting with it4  ,this is    
acknowledged3 but it is almost the only 
case of any calx being revived without  
the help of some known phlogistic       

substance2 and in this particular case  
it is not absurd to suppose1 that the   
mercury1 in becoming precipitate per se1
 may retain all its phlogiston1 as well 
as imbibe pure air1 and therefore be    
revived by simply parting with that air4
 ,in many other cases the same metal1 in
 different states1 contains more or less
 phlogiston1 as cast iron1 malleable    
iron1 and steel4 ,also there is a calx  
of mercury made by the acid of vitriol1 
which cannot be revived without the help
 of inflammable air1 or some other      
substance supposed to contain           
phlogiston3 and that the inflammable air
 is really imbibed in these processes1  
is evident1 from its wholly             
disappearing1 and nothing being left in 
the vessel in which the process is made 
beside the metal that is revived by it4 
,if precipitate per se be revived in    
inflammable air1 the air will be        
imbibed1 so that running mercury may    
contain more or less phlogiston4  ,the  
antiphlogistians also say1 that the     

diminution of atmospherical air by the  
burning of phosphorus is a proof of     
their theory2 the pure air being imbibed
 by that substance1 and nothing emitted 
from it4 ,but there is the same proof of
 phosphorus containing phlogiston1 that 
there is of dry flesh containing it2    
since the produce of the solution of it 
in nitrous acid1 and its effect upon the
 acid1 are the same1 viz4 the production
 of phlogisticated air1 and the         
phlogistication of the acid4  ,their    
proof that water is decomposed1 is1 that
 in sending steam over hot iron1        
inflammable air 7which they suppose to  
be one constituent part of it7 is       
procured2 while the other part1 viz4 the
 oxygene1 unites with the iron1 and adds
 to its weight4 ,but it is replied1 that
 the inflammable air may be well        
supposed to be the phlogiston of the    
iron1 united to part of the water1 as   
its base1 while the remainder of the    
water is imbibed by the calx2 and that  
it is mere water1 and not pure air1 or  

oxygene1 that is retained in the iron1  
is evident1 from nothing but pure water 
being recovered when this calx of iron  
is revived in inflammable air1 in which 
case the inflammable air wholly         
disappears1 taking the place of the     
water1 by which it had been expelled4   
,in answer to this it is said1 that the 
pure air expelled from the calx uniting 
with the inflammable air in the vessel1 
recomposes the water found after this   
process4 ,but in every other case in    
which any substance containing pure air 
is heated in inflammable air1 though the
 inflammable air be in part imbibed1    
some fixed air is produced1 and this    
fixed air is composed of the pure air in
 the substance and part of the          
inflammable air in the vessel4 ,thus1 if
 minium1 which contains pure air1 and   
massicot1 which contains none1 be heated
 in inflammable air1 in both the cases  
lead will be revived by the absorption  
of inflammable air2 but in the former   
case only1 and not in the latter1 will  

fixed air be produced4 ,the calx of     
iron1 therefore1 having the same effect 
with massicot1 when treated in the same 
manner1 appears to contain no more pure 
air than massicot does4  ,besides this  
explanation of the facts on which the   
new theory is founded1 which shews it to
 be unnecessary1 the old hypothesis     
being sufficient for the purpose1 some  
facts are alledged1 as inconsistent with
 the new doctrine4  ,if the calx of iron
 made by water1 and charcoal made by the
 greatest degree of heat1 be mixed      
together1 a great quantity of           
inflammable air will be produced2       
though1 according to the new theory1    
neither of these substances contained   
any water1 which they maintain to be the
 only origin of it4 ,but this fact is   
easily explained upon the doctrine of   
phlogiston2 the water in this calx      
uniting with the phlogiston of the      
charcoal1 and then forming inflammable  
air2 and it is the same kind of         
inflammable air that is made from       

charcoal and water4  ,also the union of 
inflammable and pure air1 when they are 
fired together by means of the electric 
spark1 produces not pure water1 as1     
according to the new theory1 it ought to
 do1 but nitrous acid4  ,to this it has 
been objected1 that the acid thus       
produced came from the decomposition of 
phlogisticated air1 a small portion of  
which was at first contained in the     
mixture of the two kinds of air4 ,but   
when every particle of phlogisticated   
air is excluded1 the strongest acid is  
procured4  ,they find1 indeed1 that by  
the slow burning of inflammable air in  
pure air1 they get pure water4 ,but then
 it appears1 that whenever this is the  
case1 there is a production of          
phlogisticated air1 which contains the  
necessary element of nitrous acid2 and  
this is always the case when there is a 
little surplus of the inflammable air   
that is fired along with the pure air1  
as the acid is always procured when     
there is a redundancy of pure air4      

,that much water should be procured by  
the decomposition of these kinds of air1
 is easily accounted for1 by supposing  
that water1 or steam1 is the basis of   
these1 as well as of all other kinds of 
air4  ,since air something better than  
that of the atmosphere is constantly    
produced from water by converting it    
into vapour1 and also by removing the   
pressure of the atmosphere1 and these   
processes do not appear to have any     
limits2 it seems probable1 that water   
united to the principle of heat2        
constitutes atmospherical air2 and if   
so1 it must consist of the elements of  
both dephlogisticated and phlogisticated
 air2 which is a supposition very       
different from that of the ,french      
chemists4     ,,lecture ,,xxx4   ,of    
,heat4  ,heat is an affection of bodies 
well known by the sensation that it     
excites4 ,it is produced by friction or 
compression1 as by the striking of flint
 against steel1 and the hammering of    
iron1 by the reflection or refraction of

 light1 and by the combustion of        
inflammable substances4  ,it has been   
long disputed1 whether the cause of heat
 be properly a substance1 or some       
particular affection of the particles   
that compose the substance that is      
heated4 ,but be it a substance1 or a    
principle of any other kind1 it is      
capable of being transferred from one   
body to another1 and the communication  
of it is attended with the following    
circumstances4 ,all substances are      
expanded by heat1 but some in a greater 
degree than others2 as metals more than 
earthy substances1 and charcoal more    
than wood4 ,also some receive and       
transmit heat through their substance   
more readily than others2 metals more so
 than earths1 and of the metals1 copper 
more readily than iron4 ,instruments    
contrived to ascertain the expansion of 
substances by heat1 are called          
pyrometers1 and are of various          
constructions4  ,as a standard to       
measure the degrees of heat1 mercury is 

in general preferable to any other      
substance1 on account of its readily    
receiving1 and communicating1 heat      
through its whole mass4 ,thermometers1  
therefore1 or instruments to measure the
 degrees of heat1 are generally         
constructed of it1 though1 as it is     
subject to become solid in a great      
degree of cold1 ardent spirit1 which    
will not freeze at all1 is more proper  
in that particular case4  ,the          
graduation of thermometers is arbitrary4
 ,in that of ,fahrenheit1 which is      
chiefly used in ,england1 the freezing  
point of water is #cb deg41 and the     
boiling point #bab deg4 ,in that of     
,reaumur1 which is chiefly used abroad1 
the freezing point of water is #j1 and  
the boiling point #hj4 ,to measure the  
degrees of heat above ignition1 ,mr4    
,wedgwood has happily contrived to use  
pieces of clay1 which contract in the   
fire2 and he has also been able to find 
the coincidence of the degrees in       
mercurial thermometers with those of his

 own4  ,to measure the degrees of heat  
and cold during a person's absence1     
,lord ,george ,cavendish contrived an   
instrument1 in which a small bason      
received the mercury1 that was raised   
higher than the place for which it was  
regulated by heat or cold1 without a    
power of returning4 ,but ,mr4 ,six has  
lately hit upon a better method1 viz4   
introducing into the tube of his        
thermometer a small piece of iron1 which
 is raised by the ascent of the mercury1
 and prevented from descending by a     
small spring2 but which may be brought  
back to its former place by a magnet    
acting through the glass4  ,heat1 like  
light1 is propagated in right lines2 and
 what is more remarkable1 cold observes 
the same laws4 ,for if the substance    
emitting heat without light1 as iron    
below ignition1 be placed in the focus  
of a burning mirror1 a thermometer in   
the focus of a similar mirror1 placed   
parallel to it1 though at a considerable
 distance1 will be heated by it1 and if 

a piece of ice be placed there1 the     
mercury will fall4  ,heat assists the   
solvent power of almost all menstrua2 so
 that many substances will unite in a   
certain degree of heat1 which will form 
no union at all without it1 as          
dephlogisticated and inflammable air4   
,if substances be of the same kind1 they
 will receive heat from one another1 in 
proportion to their masses4 ,thus1 if a 
quantity of water heated to #dj deg4 be 
mixed with another equal quantity of    
water heated to #bj deg41 the whole mass
 will be heated to #cj deg4 ,but if the 
substances be of different kinds1 they  
will receive heat from each other in    
different proportions1 according to     
their capacity 7as it is called7 of     
receiving heat4 ,thus1 if a pint of     
mercury of the temperature of #acf be   
mixed with a pint of water of the       
temperature of #ej1 the temperature of  
the two after mixture will not be a     
medium between those two numbers1 viz4  
#ic1 but #gf2 consequently the mercury  

was cooled #fj deg41 while the water was
 heated only #bf2 so that #bf degrees of
 heat in water correspond to #fj in     
mercury4 ,but mercury is about #ac times
 specifically heavier than water1 so    
that an equal weight of mercury would   
contain only one thirtieth part of this 
heat2 and dividing #bf by #ac1 the      
quotient is #b4 ,if weight1 therefore1  
be considered1 the heat discovered by   
water should be reckoned as #b instead  
of #fj2 and consequently when water     
receives #b degrees of heat1 an equal   
weight of mercury will receive #fj deg42
 and dividing both the numbers by #b1 if
 the heat of water be #a1 that of the   
mercury will be #cj4 ,or since they     
receive equal degrees of heat1 whether  
they discover it or not 7and the less   
they discover1 the more they retain in a
 latent state7 a pound of mercury       
contains no more than one thirtieth part
 of the heat actually existing in a     
pound of water of the same temperature4 
,water1 therefore1 is said to have a    

greater capacity for receiving and      
retaining heat1 without discovering it1 
than mercury1 in the proportion of #cj  
to #a1 if weight be considered1 or of   
#fj to #bf1 that is of #cj to #ac2 if   
bulk be the standard1 though1 according 
to some1 it is as #c to #b4  ,the       
capacity of receiving heat in the       
substance is greatest in a state of     
vapour1 and least in that of a solid2 so
 that when ice is converted into water1 
heat is absorbed1 and more still when it
 is converted into vapour2 and on the   
contrary1 when vapour is converted into 
water1 it gives out the heat which it   
had imbibed1 and when it becomes ice it 
gives out still more4  ,if equal        
quantities of ice and water be exposed  
to heat at the temperature of #cb deg41 
the ice will only become water1 without 
receiving any additional sensible heat2 
but an equal quantity of water in the   
same situation would be raised to #agh  
deg41 so that #adf degrees of heat will 
be imbibed1 and remain in latent in the 

water1 in consequence of its passing    
from a state of ice3 and heat           
communicated by a given weight of vapour
 will raise an equal weight of a        
nonevaporable substance1 of the same    
capacity with water1 #idc degrees2 so   
that much more heat is latent in steam1 
than in the water from which it was     
formed4  ,this doctrine of latent heat  
explains a great variety of phaenomena  
in nature2 as that of cooling bodies by 
evaporation1 the vapour of water1 or any
 other fluid substance1 absorbing and   
carrying off the heat they had before4  
,water1 perfectly at rest1 will fall    
considerably below the freezing point1  
and yet continue fluid3 but on the      
slightest agitation1 the congelation of 
the whole1 or part of it1 takes place   
instantly1 and if the whole be not      
solid1 it will instantly rise to #cb    
deg41 the freezing point4 ,from whatever
 cause1 some motion seems necessary to  
the commencement of congelation1 at     
least in a moderate temperature2 but    

whenever any part of the water becomes  
solid1 it gives out some of the heat it 
had before1 and that heat which was     
before latent becoming sensible1 and    
being diffused through the whole mass1  
raises its temperature4  ,on the same   
principle1 when water heated higher than
 the boiling point in a digester is     
suddenly permitted to escape in the form
 of steam1 the remainder is instantly   
reduced to the common boiling point1 the
 heat above that point being carried off
 in a latent state by the steam4  ,had  
it not been for this wise provision in  
nature1 the whole of any quantity of    
water would1 in all cases of freezing1  
have become solid at once2 and also the 
whole of any quantity that was heated to
 the point of boiling1 would have been  
converted into steam at once2           
circumstances which would have been     
extremely inconvenient1 and often fatal4
  ,this doctrine also explains the      
effect of freezing mixtures1 as that of 
salt and snow4 ,these solid substances1 

on being mixed1 become fluid1 and that  
fluid absorbing much heat1 deprives all 
the neighbouring bodies of part of what 
they had4 ,but if the temperature at    
which the mixture is made be as low as  
that to which this mixture would have   
brought it1 it has no effect1 and in a  
lower temperature this new fluid would  
become solid2 for that mixture has only 
a certain determinate capacity for heat1
 and if the neighbouring bodies have    
less heat1 they will take from it4  ,it 
has been observed1 that the comparative 
heat of bodies containing phlogiston is 
increased by calcination or combustion2 
so that the calx of iron has a greater  
capacity for heat1 and therefore        
contains more latent heat1 than the     
metal4  ,in general it is not found1    
that the same substances have their     
capacity for receiving heat increased by
 an increase of temperature2 but this is
 said to be the case with a mixture of  
ardent spirit and water1 and also that  
of spirit of vitriol and water4  ,since 

all substances contain a greater or less
 quantity of heat1 and in consequence of
 being deprived of it become colder and 
colder1 it is a question of some        
curiosity to determine the extent to    
which this can go1 or at what degree in 
the scale of a thermometer any substance
 would be absolutely cold1 or deprived  
of all heat2 and an attempt has been    
made to solve this problem in the       
following manner4 ,comparing the        
capacity of water with that of ice1 by  
means of a third substance1 viz4        
mercury1 it has been found1 that if that
 of ice be #i deg41 that of water is #aj
 deg42 so that water in becoming ice    
gives out one tenth part of its whole   
quantity of heat4 ,but it has been      
shown1 that ice in becoming water       
absorbs #adf degrees of heat4 ,this1    
therefore1 being one tenth part of the  
whole heat of water1 it must have       
contained #adfj degrees2 so that taking 
#cb degrees1 which is the freezing      
point1 from that number1 the point of   

absolute cold will be #adbf below #j of 
,fahrenheit's scale4  ,by a computation1
 made by means of the heat of           
inflammable and dephlogisticated air1 at
 the temperature of #ej1 ,dr4 ,crawford 
finds1 that it contains nearly #aeej    
degrees of heat2 so that the point of   
absolute cold will be #aejj below #j4   
,but more experiments are wanted to     
solve this curious problem to entire    
satisfaction4     ,,lecture ,,xxxi4     
,of ,animal ,heat4  ,since all animals1 
and especially those that have red      
blood1 are much hotter than the medium  
in which they live1 the source of this  
heat has become the subject of much     
investigation2 and as the most probable 
theory is that of ,dr4 ,crawford1 ,i    
shall give a short detail of the reasons
 on which it is founded4  ,having1 with 
the most scrupulous attention1          
ascertained the latent1 or1 as he calls 
it1 the absolute heat of blood1 and also
 that of the aliments of which it is    
composed1 he finds that it contains more

 than could have been derived from them4
 ,also finding that the absolute heat of
 arterial blood exceeds that of venous  
blood1 in the proportion of #aa-a_/b to 
#aj1 he concludes that it derives its   
heat from the air respired in the lungs1
 and that it parts with this latent     
heat1 so that it becomes sensible1 in   
the course of its circulation1 in which 
it becomes loaded with phlogiston1 which
 it communicates to the air in the      
lungs4  ,that this heat is furnished by 
the air1 he proves1 by finding1 that    
that which we inspire contains more heat
 than that which we expire1 or than the 
aqueous humor which we expire along with
 it1 in a very considerable proportion2 
so that if the heat contained in the    
pure air did not become latent in the   
blood1 it would raise its temperature   
higher than that of red-hot iron4 ,and  
again1 if the venous blood1 in being    
converted into arterial blood1 did not  
receive a supply of latent heat from the
 air1 its temperature would fall from   

#if to #ajd below #j in ,fahrenheit's   
thermometer4  ,that the heat procured by
 combustion has the same source1 viz4   
the dephlogisticated air that is        
decomposed in the process1 is generally 
allowed2 and ,dr4 ,crawford finds1 that 
when equal portions of air are altered  
by the respiration of a ,guinea pig1 or 
by the burning of charcoal1 the quantity
 of heat communicated by the two        
processes is nearly equal4  ,the        
following facts are also alleged in     
favour of his theory4 ,whereas animals  
which have much red blood1 and respire  
much1 have the power of keeping         
themselves in a temperature considerably
 higher than that of the surrounding    
atmosphere1 other animals1 as frogs and 
serpents1 are nearly of the same        
temperature with it2 and those animals  
which have the largest respiratory      
organs1 as birds1 are the warmest2 also 
the degree of heat is in some measure   
proportionable to the quantity of air   
that is respired in a given time1 as in 

violent exercise4  ,it has been         
observed1 that animals in a medium      
hotter than the blood have a power of   
preserving themselves in the same       
temperature4 ,in this case the heat is  
probably carried off by perspiration1   
while the blood ceases to receive1 or   
give out1 any heat2 and ,dr4 ,crawford  
finds1 that when an animal is placed in 
a warm medium the colour of the venous  
blood approaches nearer to that of the  
arterial than when it is placed in a    
colder medium2 and also1 that it        
phlogisticates the air less than in the 
former case2 so that in these           
circumstances respiration has not the   
same effect that it has in a colder     
temperature1 in giving the body an      
additional quantity of heat2 which is an
 excellent provision in nature1 as the  
heat is not wanted1 but1 on the         
contrary1 would prove inconvenient4     
,,lecture ,,xxxii4   ,of ,light4        
,another most important agent in nature1
 and one that has a near connexion with 

heat1 is light1 being emitted by all    
bodies in a state of ignition1 and      
especially by the sun1 the great source 
of light and of heat to this habitable  
world4  ,whether light consists of      
particles of matter 7which is most      
probable7 or be the undulation of a     
peculiar fluid1 filling all space1 it is
 emitted from all luminous bodies in    
right lines4  ,falling upon other       
bodies1 part of the light is reflected  
at an angle equal to that of its        
incidence1 though not by impinging on   
the reflecting surface1 but by a power  
acting at a small distance from it4 ,but
 another part of the light enters the   
body1 and is refracted or bent towards1 
or from1 the perpendicular to the       
surface of the new medium1 if the       
incidence be oblique to it4 ,in general1
 rays of light falling obliquely on any 
medium are bent as if they were         
attracted by it1 when it has a greater  
density1 or contains more of the        
inflammable principle1 than the medium  

through which it was transmitted to it4 
,more of the rays are reflected when    
they fall upon a body with a small      
degree of obliquity to its surface1 and 
more of them are transmitted1 or enter  
the body1 when their incidence is nearer
 to a perpendicular4  ,the velocity with
 which light is emitted or reflected is 
the same1 and so great that it passes   
from the sun to the earth in about eight
 minutes and twelve seconds4  ,rays of  
light emitted or reflected from a body  
entering the pupil of the eye1 are so   
refracted by the humours of it1 as to be
 united at the surface of the retina1   
and so make images of the objects1 by   
means of which they are visible to us2  
and the magnifying power of telescopes  
or microscopes depends upon contriving1 
by means of reflections or refractions1 
that pencils of rays issuing from every 
point of any object shall first diverge1
 and then converge1 as they would have  
done from a much larger object1 or from 
one placed much nearer to the eye4      

,when a beam of light is bent out of its
 course by refraction1 all the rays of  
which it consists are not equally       
refracted1 but some of them more and    
others less2 and the colour which they  
are disposed to exhibit is connected    
invariably with the degree of their     
refrangibility2 the red-coloured rays   
being the least1 and the violet the most
 refrangible1 and the rest being more or
 less so in proportion to their nearness
 to these1 which are the extremes1 in   
the following order1 violet1 indigo1    
blue1 green1 yellow1 orange1 red4       
,these colours1 when separated as much  
possible1 are still contiguous2 and all 
the shades of each colour have likewise 
their separate and invariable degrees of
 refrangibility4 ,when separated as     
distinctly as possible1 they divide the 
whole space between them exactly as a   
musical chord is divided in order to    
found the several notes and half notes  
of an octave4  ,these                   
differently-coloured rays of light are  

also separated in passing through the   
transparent medium of air and water1 in 
consequence of which the sky appears    
blue and the sea green1 these rays being
 returned1 while the red ones proceed to
 a greater distance4 ,by this means also
 objects at the bottom of the sea appear
 to divers red1 and so do all objects   
enlightened by an evening sun4  ,the    
mixture of all the differently-coloured 
rays1 in the proportions in which they  
cover the coloured image above          
mentioned1 makes a white1 and the       
absence of all light is blackness4  ,by 
means of the different refrangibility of
 light1 the colours of the rainbow may  
be explained4  ,the distance to which   
the differently-coloured rays are       
separated from each other is not in     
proportion to the mean refractive power 
of the medium1 but depends upon the     
peculiar constitution of the substance  
by which they are refracted4 ,the       
dispersing power of glass1 into the     
composition of which lead enters1 is    

great in proportion to the mean         
refraction2 and it is proportionally    
little in that glass in which there is  
much alkaline salt4 ,the construction of
 achromatic telescopes depends upon this
 principle4  ,not only have different   
rays of light these different properties
 with respect to bodies1 so as to be    
more or less refracted1 or dispersed1 by
 them1 but different sides of the same  
rays seem to have different properties1 
for they are differently affected on    
entering a piece of island crystal4     
,with the same degree of incidence2 part
 of the pencil of rays1 consisting of   
all the colours1 proceeds in one        
direction1 and the rest in a different  
one2 so that objects seen through a     
piece of this substance appear double4  
,at the surface of all bodies rays of   
light are promiscuously reflected1 or   
transmitted4  ,but if the next surface  
be very near to it1 the rays of one     
colour chiefly are reflected1 and the   
rest transmitted1 and these places occur

 alternately for rays of each of the    
colours in passing from the thinnest to 
the thickest parts of the medium2 so    
that several series1 or orders1 of      
colours will be visible on the surface  
of the same thin transparent body4 ,on  
this principle coloured rings appear    
between a plane and a convex lens1 in a 
little oil on the surface of water1 and 
in bubbles made with soap and water4    
,when rays of light pass near to any    
body1 so as to come within the sphere of
 its attraction and repulsion1 an       
inflection takes place2 all the kinds of
 rays being bent towards1 or from1 the  
body1 and these powers affecting some   
rays more than others1 they are by this 
means also separated from each other1 so
 that coloured streaks appear both      
within the shadow1 and the outside of   
it1 the red rays being inflected at the 
greatest distance from the body4  ,part 
of the light which enters bodies is     
retained within them1 and proceeds no   
farther2 but so loosely in some kinds of

 bodies1 that a small degree of heat is 
sufficient to expel it again1 so as to  
make the body visible in the dark3 but  
the more heat is applied1 the sooner is 
all the light expelled4 ,this is a      
strong argument for the materiality of  
light4 ,bolognian phosphorus is a       
substance which has this property2 but a
 composition made by ,mr4 ,canton1 of   
calcined oyster-shells and sulphur1 in a
 much greater degree4 ,however1 white   
paper1 and most substances1 except the  
metals1 are possessed of this property  
in a small degree4  ,some bodies1       
especially phosphorus1 and animal       
substances tending to putrefaction1 emit
 light without being sensibly hot4  ,the
 colours of vegetables1 and likewise    
their taste and smell1 depend upon      
light4 ,it is also by means of light    
falling on the leaves and other green   
parts of plants1 that they emit         
dephlogisticated air1 which preserves   
the atmosphere fit for respiration4  ,it
 is light that imparts colour to the    

skins of men1 by means of the fluid     
immediately under them4 ,this is the    
cause of tanning1 of the copper colour  
of the ,north ,americans1 and the black 
of the ,negroes4 ,light also gives      
colour to several other substances1     
especially the solutions of mercury in  
acids4     ,,lecture ,,xxxiii4   ,of    
,magnetism4  ,magnetism is a property   
peculiar to iron1 or some ores of it4   
,the earth itself1 owing probably to the
 iron ores contained in it1 has the same
 property4 ,but though all iron is acted
 upon by magnetism1 steel only is       
capable of having the power communicated
 to it4  ,every magnet has two poles1   
denominated north and south1 each of    
which attracts the other1 and repels    
that of the same kind with itself4 ,if a
 magnet be cut into two parts1 between  
the two poles1 it will make two magnets1
 the parts that were contiguous becoming
 opposite poles4  ,though the poles of a
 magnet are denominated north and south1
 they do not constantly1 and in all     

parts of the earth1 point due north or  
south1 but in most places to the east or
 west of them1 and with a considerable  
variation in a course of time4 ,also a  
magnet exactly balanced at its center   
will have a declination from an         
horizontal position of about #gj        
degrees4 ,the former is called the      
variation1 and the latter the dipping of
 the magnetic needle4  ,a straight bar  
of iron which has been long fixed in a  
vertical position1 will become a magnet1
 the lower end becoming a north pole1   
and the upper end a south one2 for if it
 be suspended horizontally1 the lower   
end will point towards the north1 and   
the upper end towards the south4 ,also  
any bar of iron1 not magnetical1 held in
 a vertical position1 will become a     
temporary magnet1 the lower end becoming
 a north pole1 and the upper end a south
 one2 and a few strokes of a hammer will
 fix the poles for a short time1 though 
the position of the ends be changed4    
,magnetism may likewise be given to a   

bar of iron by placing it firmly in the 
position of the dipping-needle1 and     
rubbing it hard one way with a polished 
steel instrument4 ,iron will also become
 magnetical by ignition and quenching it
 in water in the position of the        
dipping-needle4  ,magnetism acts1       
without any diminution of its force1    
through any medium2 and iron not        
magnetical will have that power while it
 is in connexion with a magnet1 or      
rather the power of the magnet is       
extended through the iron4  ,steel      
filings gently thrown upon a magnet1    
adhere to it in a curious manner2 and   
the filings1 acquiring magnetism by the 
contact1 adhere together1 and form a    
number of small magnets1 which arrange  
themselves according to the attraction  
of the poles of the original magnet4    
,this experiment is made to the most    
advantage upon a piece of pasteboard1 or
 paper1 placed over the magnet4         
,magnetism is communicated by the       
friction1 or the near position1 of a    

magnet to a piece of steel of a size    
less than it4 ,for this reason a        
combination of magnetical bars will have
 a greater effect than a single one2 and
 in the following manner1 beginning     
without any magnetism at all1 the       
greatest quantity may be procured4 ,six 
bars of steel may be rendered slightly  
magnetical by fixing each of them       
successively to an upright poker1 and   
stroking it several times from the      
bottom to the top with the lower end of 
an old pair of tongs4 ,if then four of  
these bars be joined1 the magnetism of  
the remaining two will be much increased
 by a proper method of rubbing with     
them2 and by changing their places1     
joining the strongest1 and acting upon  
the weakest1 they may all be made as    
magnetical as they are capable of being4
  ,the strength of a natural magnet may 
be increased by covering its polar      
extremities with steel4 ,this is called 
the arming of the loadstone4  ,to       
account for the variation of the needle1

 ,dr4 ,halley supposed the earth to     
consist of two parts1 an external shell 
and an internal nucleus1 detached1 and  
having a revolution distinct from it2   
and that the action of the poles of the 
shell and of the nucleus would explain  
all the varieties in the position of the
 needle4 ,but others think that the     
cause of the magnetism of the earth is  
not within1 but without itself4 ,one    
reason for this opinion is1 that a      
magnet is liable to be affected by a    
strong aurora borealis2 and another is1 
that the variation of the needle        
proceeds in such manner as supposes that
 the motion of the nucleus must be      
quicker than that of the shell of the   
earth2 whereas1 since it is most natural
 to suppose that motion was communicated
 to the nucleus by the shell1 it would  
be slower4  ,some idea of the quantity  
and the progress of the variation of the
 needle may be formed from the following
 facts4--,at the ,cape of ,good ,hope1  
when it was discovered by the           

,portuguese1 in #adhf1 there was no     
variation1 the needle there pointing due
 north2 in #afbb it was about #b degrees
 westward1 in #afge it was #h deg4 ,w4  
in #agjj about #aa deg4 ,w4 in #agef    
about #ah deg4 ,w4 and in #aggd about   
#ba-a_/b deg4 ,w4 ,in ,london1 in #aehj1
 the variation was #aa degrees #ae      
seconds ,e42 in #afbb it was #f deg4 ,e4
 in #afcd it was #d deg4 #e min4 ,e4 in 
#afeg it was nothing at all2 in #afgb it
 was #b deg4 #cj min4 ,w4 in #afib it   
was #f deg4 ,w4 in #agec it was about   
#af ,w4 and at present it is about #ba  
,w4  ,the longitude may in some places  
be found by the variation of the needle2
 and ,mr4 ,churchman1 of ,america1      
having given much attention to the      
subject1 comparing the observations of  
others1 and many of his own1 thinks that
 he has found a method of determining   
the longitude to a great degree of      
certainty1 in most cases1 by this means4
  ,he says there are two magnetic poles 
of the earth1 one to the north and the  

other to the south1 at different        
distances from the poles of the earth1  
and revolving in different times2 and   
from the combined influence of these two
 poles he deduces rules for the position
 of the needle in all places of the     
earth1 and at all times1 past1 present1 
or to come4  ,the north magnetic pole1  
he says1 makes a complete revolution in 
#dbf years1 #gg days1 #i hours1 and the 
south pole in about #edei years4 ,in the
 beginning of the year #aggg the north  
magnetic pole was in #gf deg4 #d min4   
north latitude2 and in longitude from   
,greenwich #adj deg4 east2 and the south
 was in #gb deg4 south latitude1 and    
#adj deg4 east from ,greenwich4         
,,lecture ,,xxxiv4   ,of ,electricity4  
,electricity is a property belonging to1
 or capable of being communicated to1   
all substances whatever2 and whereas by 
some of them it is transmitted with     
great ease1 and by others with much     
difficulty1 they have been divided into 
two classes1 and denominated conductors 

or non-conductors of electricity4 ,also 
the latter receiving this power by      
friction1 and other means1 are termed   
electrics1 and the former non-electrics4
  ,metals of all kinds1 and water1 are  
conductors1 though in very different    
degrees2 so also is charcoal4 ,all other
 substances1 and also a perfect vacuum1 
are non-conductors of electricity4 ,but 
many of these substances1 when they are 
made very hot1 as glass1 resin1 baked   
wood1 and perhaps all the rest on which 
the experiment can be made in this      
state1 are conductors4  ,it is the      
property of all kinds of electrics1 when
 they are rubbed by bodies different    
from themselves1 to attract light       
substances of all kinds1 to exhibit an  
appearance of light1 attended with a    
particular sound1 on the approach of any
 conductor2 and if the nostrils are     
presented1 they are affected with a     
smell like that of phosphorus4 ,this    
attraction is most easily explained by  
supposing that electricity is produced  

by a fluid exceedingly elastic1 or      
repulsive of itself1 and attracted by   
all other substances4  ,an electric     
exhibiting the appearances above        
mentioned1 is said to be excited1 and   
some of them1 particularly the          
tourmaline1 are excited by heating and  
cooling1 as well as by friction4 ,it    
appears1 however1 that excitation       
consists in the mere transferring of    
electricity from one substance to       
another1 and that the great source of   
electricity is in the earth4 ,on this   
account it is necessary to the          
considerable excitation of any electric1
 that the substance against which it is 
rubbed 7hence termed the rubber7 have a 
communication with the earth1 by means  
of conductors2 for if the rubber be     
insulated1 that is cut off from all     
communication with the earth by means of
 electrics1 the friction has but little 
effect4  ,when insulated bodies have    
been attracted by1 and brought into     
contact with1 an excited electric1 they 

begin to be repelled by it1 and also to 
repel one another2 nor will they be     
attracted again till they have been     
brought into contact with some conductor
 communicating with the earth2 but after
 this they will be attracted as at      
first4  ,if conductors be insulated1    
electric powers may be communicated to  
them by the approach of excited         
electrics1 or the contact of other      
electrified bodies4 ,they will then     
attract light bodies1 and give sparks1  
c4 like the excited electrics           
themselves4  ,when electricity is       
strongly communicated to insulated      
animal bodies1 the pulse is quickened1  
and perspiration increased2 and if they 
receive1 or part with1 their electricity
 on a sudden1 a painful sensation is    
felt at the place of communication4 ,but
 what is more extraordinary1 is1 that   
the influence of the brain and nerves   
upon the muscles seems to be of an      
electric nature4  ,this is one of the   
last and most important of all          

philosophical discoveries4 ,i shall1    
therefore1 give the result of all the   
observations that have hitherto been    
made on the subject1 in a series of     
propositions1 drawn up by an intelligent
 friend1 who has given much more        
attention to it than ,i have done4  #a4 
,the nerve of the limb of an animal     
being laid bare1 and surrounded with a  
piece of sheet lead1 or of tinfoil1 if a
 communication be formed between the    
nerve thus armed and any of the         
neighbouring muscles1 by means of a     
piece of zinc1 strong contractions will 
be produced in the limb4  #b4 ,if a     
portion of the nerve which has been laid
 bare be armed as above1 contractions   
will be produced as powerfully1 by      
forming the communication between the   
armed and bare part of the nerve1 as    
between the armed part and muscle4  #c4 
,a similar effect is produced by arming 
a nerve and simply touching the armed   
part of the nerve with the metallic     
conductor4  #d4 ,contractions will take 

place if a muscle be armed1 and a       
communication be formed by means of the 
conductor between it and a neighbouring 
nerve4 ,the same effect will be produced
 if the communication be formed between 
the armed muscle and another muscle1    
which is contiguous to it4  #e4         
,contractions may be produced in the    
limb of an animal by bringing the pieces
 of metal into contact with each other  
at some distance from the limb1 provided
 the latter make part of a line of      
communication between the two metallic  
conductors4  ,the experiment which      
proves this is made in the following    
manner4 ,the amputated limb of an animal
 being placed upon a table1 let the     
operator hold with one hand the         
principal nerve1 previously laid bare1  
and in the other let him hold a piece of
 zinc2 let a small plate of lead or     
silver be then laid upon the table1 at  
some distance from the limb1 and a      
communication be formed1 by means of    
water1 between the limb and the part of 

the table where the metal is lying4 ,if 
the operator touch the piece of silver  
with the zinc1 contractions will be     
produced in the limb the moment that the
 metals come into contact with each     
other4 ,the same effect will be produced
 if the two pieces of metal be          
previously placed in contact1 and the   
operator touch one of them with his     
finger4 ,this fact was discovered by    
,mr4 ,william ,cruikshank4  #f4         
,contractions can be produced in the    
amputated leg of a frog1 by putting it  
into water1 and bringing the two metals 
into contact with each other at a small 
distance from the limb4  #g4 ,the       
influence which has passed through1 and 
excited contractions in1 one limb1 may  
be made to pass through1 and excite     
contractions in1 another limb4 ,in      
performing this experiment it is        
necessary to attend to the following    
circumstances3 let two amputated limbs  
of a frog be taken2 let one of them be  
laid upon a table1 and its foot be      

folded in a piece of silver2 let a      
person lift up the nerve of this limb   
with a silver probe1 and another person 
hold in his hand a piece of zinc1 with  
which he is to touch the silver         
including the foot2 let the person      
holding the zinc in one hand catch with 
the other the nerve of the second limb1 
and he who touches the nerve of the     
first limb is to hold in his other hand 
the foot of the second2 let the zinc now
 be applied to the silver including the 
foot of the first limb1 and contractions
 will immediately be excited in both    
limbs4  #h4 ,the heart is the only      
involuntary muscle in which contractions
 can be excited by these experiments4   
#i4 ,contractions are produced more     
strongly1 the farther the coating is    
placed from the origin of the nerve4    
#aj4 ,animals which were almost dead    
have been found to be considerably      
revived by exciting this influence4     
#aa4 ,when these experiments are        
repeated upon an animal that has been   

killed by opium1 or by the electric     
shock1 very slight contractions are     
produced2 and no contractions whatever  
will take place in an animal that has   
been killed by corrosive sublimate1 or  
that has been starved to death4  #ab4   
,zinc appears to be the best exciter    
when applied to gold1 silver1 molybdena1
 steel1 or copper4 ,the latter metals1  
however1 excite but feeble contractions 
when applied to each other4 ,next to    
zinc1 in contact with these metals1 tin 
and lead1 and silver and lead1 appear to
 be the most powerful exciters4  ,at    
least two kinds of fishes1 the torpedo  
and the electrical eel1 have a voluntary
 power of giving so strong a shock to   
the water in which they swim1 as to     
affect fishes and other animals which   
come near them2 and by a conducing      
communication between different parts of
 these fishes1 an electric shock may be 
given exactly like that of the ,leyden  
phial1 which will be described          
hereafter2 and if the communication be  

interrupted1 a flash of electric light  
will be perceived4  ,the growth of      
vegetables is also quickened by         
electricity4     ,,lecture ,,xxxv4      
,the same ,subject continued4  ,no      
electric can be excited without         
producing electric appearances in the   
body with which it is excited1 provided 
that body be insulated2 for this        
insulated rubber will attract light     
bodies1 give sparks1 and make a snapping
 noise1 upon the approach of a          
conductor1 as well as the excited       
electric4  ,if an insulated conductor be
 pointed1 or if a pointed conductor1    
communicating with the earth1 be held   
pretty near it1 little or no electric   
appearance will be exhibited1 only a    
light will appear at each of the points 
during the act of excitation1 and a     
current of air will be sensible from off
 them both4  ,the effect of pointed     
bodies is best explained on the         
supposition of the electric matter in   
one body repelling that in another2 and 

consequently the electricity belonging  
to a body with a large surface making a 
greater resistance to the entrance of   
foreign electricity than that belonging 
to a smaller4  ,these two electricities1
 viz4 that of the excited electric1 and 
that of the rubber1 though similar to1  
are the reverse of1 one another4 ,a body
 attracted by the one will be repelled  
by the other1 and they will attract1 and
 in all respects act upon1 one another  
more sensibly than upon other bodies2 so
 that two pieces of glass or silk       
possessed of contrary electricities will
 cohere firmly together1 and require a  
considerable force to separate them4    
,these two electricities having been    
first discovered by producing one of    
them from glass1 and the other from     
amber1 sealing-wax1 sulphur1 rosin1 c4  
first obtained the names of vitreous and
 resinous electricity2 and it being     
afterwards imagined that one of them was
 a redundancy1 and the other a          
deficiency1 of a supposed electric      

fluid1 the former has obtained the name 
of positive1 and the latter that of     
negative1 electricity2 and these terms  
are now principally in use4  ,positive  
and negative electricity may be         
distinguished from each other by the    
manner in which they appear at the      
points of bodies4 ,from a pointed body  
electrified positively1 there issues a  
stream of light1 divided into denser    
streams1 at the extremities2 whereas1   
when the point is electrified           
negatively1 the light is more minutely  
divided1 and diffused equally4 ,the     
former of these is called a brush1 and  
the latter a star4  ,if a conductor not 
insulated be brought within the         
atmosphere 7that is the sphere of       
action7 of any electrified body1 it     
acquires the electricity opposite to    
that of the electrified body1 and the   
nearer it is brought1 the stronger      
opposite electricity does it acquire1   
till the one receive a spark from the   
other1 and then the electricity of both 

will be discharged4  ,the electric      
substance which separates the two       
conductors possessing these two opposite
 kinds of electricity1 is said to be    
charged4 ,plates of glass are the most  
convenient for this purpose1 and the    
thinner the plate the greater is the    
charge it is capable of holding4 ,the   
conductors contiguous to each side of   
the glass are called their coating4     
,agreeably to the above-mentioned       
general principle1 it is necessary that 
one side of the charged glass have a    
communication with the rubber1 while the
 other receives the electricity from the
 conductor1 or with the conductor1 while
 the other receives from the rubber4    
,it follows also1 that the two sides of 
the plate thus charged are always       
possessed of the two opposite           
electricities2 that side which          
communicates with the excited electric  
having the electricity of the electric1 
and that which communicates with the    
rubber1 that of the rubber4  ,there is1 

consequently1 a very eager attraction   
between these two electricities with    
which the different sides of the plate  
are charged1 and when a proper          
communication is made by means of       
conductors1 a flash of electric light1  
attended with a report 7which is greater
 or less in proportion to the quantity  
of electricity communicated to them1 and
 the goodness of the conductors7 is     
perceived between them1 and the         
electricity of both sides is thereby    
discharged4  ,the substance of the glass
 itself in1 or upon1 which these        
electricities exist1 is impervious to   
electricity1 and does not permit them to
 unite2 but if they be very strong1 and 
the plate of glass very thin1 they will 
force a passage through the glass4      
,this1 however1 always breaks the glass1
 and renders it incapable of another    
charge4  ,the flash of light1 together  
with the explosion between the two      
opposite sides of a charged electric1 is
 generally called the electric shock1 on

 account of the disagreeable sensation  
it gives any animal whose body is made  
use of to form the communication been   
them4  ,the electric shock is always    
found to perform the circuit from one   
side of the charged glass to the other  
by the shortest passage through the best
 conductors4 ,common communicated       
electricity also observes the same rule 
in its transmission from one body to    
another4  ,it has not been found1 that  
the electric shock takes up any sensible
 space of time in being transmitted to  
the greatest distances4  ,the electric  
shock1 as also the common electric      
spark1 displaces the air through which  
it passes2 and if its passage from      
conductor to conductor be interrupted by
 non-conductors of a moderate thickness1
 it will rend and tear them in its      
passage1 in such a manner as to exhibit 
the appearance of a sudden expansion of 
the air about the center of the shock4  
,if the electric circuit be interrupted1
 the electric matter1 during the        

discharge1 will pass to any other body  
that lies near its path1 and instantly  
return4 ,this may be called the lateral 
explosion4 ,the effect of this lateral  
explosion through a brass chain1 when   
the quantity of electricity is very     
great1 will be the discolouring and     
partial burning of the paper on which it
 lies4  ,if a great quantity of         
electricity be accumulated1 as in a     
battery1 the explosion will pass over   
the surfaces of imperfect conductors    
without entering them1 and the effect   
will be a strong concussion of the      
substance4 ,also the electric matter    
thus accumulated and condensed will1 by 
its repulsion1 form concentric circles1 
which will appear by melting the surface
 of a flat piece of metal on which the  
explosion is received4  ,if an electric 
shock1 or strong spark1 be made to pass 
through1 or over1 the belly of a muscle1
 it forces it to contract1 as in a      
convulsion4  ,if a strong shock be sent 
through a small animal body1 it will    

often deprive it instantly of life4     
,when the electric shock is very strong1
 it will give polarity to magnetic      
needles1 and sometimes it reverses their
 poles4  ,great shocks1 by which animals
 are killed1 are said to hasten         
putrefaction4  ,electricity and         
lightning are in all respects the same  
thing2 since every effect of lightning  
may be imitated by electricity1 and     
every experiment in electricity may be  
made with lightning1 brought down from  
the clouds by means of insulated pointed
 rods of metal4     ,,lecture ,,xxxvi4  
,the same ,subject continued4  ,three   
curious and important instruments1 which
 are among the latest improvements in   
electricity1 deserve a particular       
explanation1 and in all of them the     
effect depends upon the general         
principles mentioned above1 viz4 that   
bodies placed within the influence1 or1 
as it is usually termed1 within the     
atmosphere1 of an electrified body1 are 
affected by a contrary electricity1 and 

that these two electricities mutually   
attract each other4 ,these instruments  
are the electrophorus1 the condenser of 
electricity1 and the doubler of it4     
,the electrophorus consists of an       
insulated conducting plate applied to an
 insulated electric4 ,if the latter have
 any electricity communicated to it1 for
 example the negative1 the positive     
electricity of the former will be       
attracted by it1 and consequently the   
plate will be capable of receiving      
electricity from any body communicating 
with the earth2 being1 in this          
situation1 capable of containing more   
electricity than its natural quantity4  
,consequently1 when it is removed from  
the lower plate1 and the whole of its   
electricity equally diffused through it1
 it will appear to have a redundance1   
and therefore will give a spark to any  
body communicating with the earth4      
,being then replaced upon the electric1 
and touched by any body communicating   
with the earth1 it will be again        

affected as before1 and give a spark on 
being raised2 and this process may be   
continued at pleasure1 the electrophorus
 supplying the place of any other       
electrical machine4  ,if the conducting 
plate of the electrophorus be applied to
 a piece of dry wood1 marble1 or any    
other substance through which           
electricity can pass but very slowly1 or
 if the insulated conducting plate be   
covered with a piece of thin silk1 which
 will make some resistance to the       
passage of electricity1 and it be then  
applied to another plate communicating  
with the earth2 and if1 in either of    
these cases1 a body with a large surface
 possessed of a weak electricity be     
applied to the conducting plate1 the    
weak electricity not being able to      
overcome the obstruction presented to   
it1 so as to be communicated to the     
other plate1 will affect it with the    
contrary electricity1 and this reacting 
on the first plate1 will condense its   
electricity on that part of the plate to

 which it is contiguous2 in consequence 
of which its capacity of receiving      
electricity will be increased2 so that  
on the separation of the two plates1    
that electricity which was before       
condensed1 being equally diffused       
through the whole plate1 will have a    
greater intensity than it had before1   
attracting light bodies1 or even giving 
a spark1 when the body from which it    
received its electricity was incapable  
of it4 ,for though it contained a great 
quantity of electricity1 it was diffused
 through so large a space that its      
intensity was very small4 ,this         
instrument is therefore called a        
condenser of electricity4  ,if an       
insulated plate of metal possessing the 
smallest degree of electricity be       
presented very near to another plate    
communicating with the earth1 it will   
affect this plate with the opposite     
electricity2 and this being1 in the same
 manner1 applied to a third plate1 will 
put it into the same state with the     

first4 ,if then these two plates be     
joined1 and the first plate be presented
 to either of them1 its own electricity 
being attracted by that of the plate    
presented1 that of the other will be    
drawn into it1 so that its quantity will
 be doubled4 ,the same process being    
repeated1 will again double the         
electricity of this plate1 till1 from   
being quite insensible to the most      
exquisite electrometer1 it will become  
very conspicuous1 or even give sparks4  
,this instrument is therefore called a  
doubler of electricity1 of excellent use
 in ascertaining the quality of         
atmospherical electricity when ever so  
small4 ,if this instrument be so        
constructed that these three plates can 
be successively presented to one another
 by the revolution of one of them on an 
axis1 it is called the revolving        
doubler2 and in this form it is most    
convenient for use4   ,,the ,,end4      
,transcriber's ,note3 ,details of       
corrections      ,position              

,original     ,correction               
,lecture ,i1 first paragraph            
limestone    lime-stone         ,lecture
 ,i1 last paragraph           attraction
 attraction1      ,lecture ,,iii1 first 
paragraph        viz          viz4      
,lecture ,,iii1 last paragraph          
#a4           #a                        
,lecture ,,xvii1 penultimate paragraph  
dissoved     dissolved          ,lecture
 ,,xix1 ,of ,calcareous ,earth  hundreth
     hundredth          ,lecture ,,xxvi1
 ,of ,semi-metals      ignates          
ignites            ,lecture ,,xxviii1   
first paragraph     animony             
antimony