,,the ,,chemical ,,history ,,of ,a ,,candle ,a ,,course ,,of ,,lectures ,,delivered ,,before ,a ,,juvenile ,,audience ,,at ,,the ,,royal ,,institution ,,by ,,michael ,,faraday1 ,d4,c4,l41 ,f4,r4,s4 ,,edited ,,by ,,william ,,crookes1 ,f4,c4,s4 ,a ,,new ,,impression1 ,,with ,,illustrations ,,london ,,chatto ,,windus #aijh ,,preface ,from the primitive pine-torch to the paraffin candle1 how wide an interval6 between them how vast a contrast6 ,the means adopted by man to illuminate his home at night1 stamp at once his position in the scale of civilisation4 ,the fluid bitumen of the far ,east1 blazing in rude vessels of baked earth2 the ,etruscan lamp1 exquisite in form1 yet ill adapted to its office2 the whale1 seal1 or bear fat1 filling the hut of the ,esquimaux or ,lap with odour rather than light2 the huge wax candle on the glittering altar1 the range of gas lamps in our streets1--all have their stories to tell4 ,all1 if they could speak 7and1 after their own manner1 they can71 might warm our hearts in telling1 how they have ministered to man's comfort1 love of home1 toil1 and devotion4 ,surely1 among the millions of fire-worshippers and fire-users who have passed away in earlier ages1 some have pondered over the mystery of fire2 perhaps some clear minds have guessed shrewdly near the truth4 ,think of the time man has lived in hopeless ignorance3 think that only during a period which might be spanned by the life of one man1 has the truth been known4 ,atom by atom1 link by link1 has the reasoning chain been forged4 ,some links1 too quickly and too slightly made1 have given way1 and been replaced by better work2 but now the great phenomena are known--the outline is correctly and firmly drawn--cunning artists are filling in the rest1 and the child who masters these ,lectures knows more of fire than ,aristotle did4 ,the candle itself is now made to light up the dark places of nature2 the blowpipe and the prism are adding to our knowledge of the earth's crust2 but the torch must come first4 ,among the readers of this book some few may devote themselves to increasing the stores of knowledge3 the ,lamp of ,science must burn4 8,alere flammam40 ,w4 ,,crookes4 ,,contents4 ,,lecture ,i4 ,a ,,candle3 ,,the ,,flame--,,its ,,sources--,,structure--,,mobility--,,br ightness ,,lecture ,,ii4 ,,brightness ,,of ,,the ,,flame--,,air ,,necessary ,,for ,,combustion--,,production ,,of ,,water ,,lecture ,,iii4 ,,products3 ,,water ,,from ,,the ,,combustion--,,nature ,,of ,,water--,a ,,compound--,,hydrogen ,,lecture ,,iv4 ,,hydrogen ,,in ,,the ,,candle--,,burns ,,into ,,water--,,the ,,other ,,part ,,of ,,water--,,oxygen ,,lecture ,v4 ,,oxygen ,,present ,,in ,,the ,,air--,,nature ,,of ,,the ,,atmosphere--,,its ,,properties--,,other ,,products ,,from ,,the ,,candle--,,carbonic ,,acid--,,its ,,properties ,,lecture ,,vi4 ,,carbon ,,or ,,charcoal--,,coal-,,gas--,,respiration ,,and ,,its ,,analogy ,,to ,,the ,,burning ,,op ,a ,,candle--,,conclusion ,,lecture ,,on ,,platinum4 ,,notes4 ,,the ,,chemical ,,history ,,of ,a ,,candle ,,lecture ,i4 ,a ,,candle3 ,,the ,,flame--,,its ,,sources--,,structure--,,mobility--,,br ightness4 ,i purpose1 in return for the honour you do us by coming to see what are our proceedings here1 to bring before you1 in the course of these lectures1 the ,chemical ,history of a ,candle4 ,i have taken this subject on a former occasion2 and were it left to my own will1 ,i should prefer to repeat it almost every year--so abundant is the interest that attaches itself to the subject1 so wonderful are the varieties of outlet which it offers into the various departments of philosophy4 ,there is not a law under which any part of this universe is governed which does not come into play1 and is touched upon in these phenomena4 ,there is no better1 there is no more open door by which you can enter into the study of natural philosophy1 than by considering the physical phenomena of a candle4 ,i trust1 therefore1 ,i shall not disappoint you in choosing this for my subject rather than any newer topic1 which could not be better1 were it even so good4 ,and before proceeding1 let me say this also--that though our subject be so great1 and our intention that of treating it honestly1 seriously1 and philosophically1 yet ,i mean to pass away from all those who are seniors amongst us4 ,i claim the privilege of speaking to juveniles as a juvenile myself4 ,i have done so on former occasions--and1 if you please1 ,i shall do so again4 ,and though ,i stand here with the knowledge of having the words ,i utter given to the world1 yet that shall not deter me from speaking in the same familiar way to those whom ,i esteem nearest to me on this occasion4 ,and now1 my boys and girls1 ,i must first tell you of what candles are made4 ,some are great curiosities4 ,i have here some bits of timber1 branches of trees particularly famous for their burning4 ,and here you see a piece of that very curious substance taken out of some of the bogs in ,ireland1 called candle-wood1--a hard1 strong1 excellent wood1 evidently fitted for good work as a resister of force1 and yet withal burning so well that where it is found they make splinters of it1 and torches1 since it burns like a candle1 and gives a very good light indeed4 ,and in this wood we have one of the most beautiful illustrations of the general nature of a candle that ,i can possibly give4 ,the fuel provided1 the means of bringing that fuel to the place of chemical action1 the regular and gradual supply of air to that place of action--heat and light--all produced by a little piece of wood of this kind1 forming1 in fact1 a natural candle4 ,but we must speak of candles as they are in commerce4 ,here are a couple of candles commonly called dips4 ,they are made of lengths of cotton cut off1 hung up by a loop1 dipped into melted tallow1 taken out again and cooled1 then re-dipped until there is an accumulation of tallow round the cotton4 ,in order that you may have an idea of the various characters of these candles1 you see these which ,i hold in my hand--they are very small1 and very curious4 ,they are1 or were1 the candles used by the miners in coal mines4 ,in olden times the miner had to find his own candles2 and it was supposed that a small candle would not so soon set fire to the fire-damp in the coal mines as a large one2 and for that reason1 as well as for economy's sake1 he had candles made of this sort--#bj1 #cj1 #dj1 or #fj to the pound4 ,they have been replaced since then by the steel-mill1 and then by the ,davy-lamp1 and other safety-lamps of various kinds4 ,i have here a candle that was taken out of the ,royal ,george#a1 it is said1 by ,colonel ,pasley4 ,it has been sunk in the sea for many years1 subject to the action of salt water4 ,it shews you how well candles may be preserved2 for though it is cracked about and broken a good deal1 yet1 when lighted1 it goes on burning regularly1 and the tallow resumes its natural condition as soon as it is fused4 ,mr4 ,field1 of ,lambeth1 has supplied me abundantly with beautiful illustrations of the candle and its materials4 ,i shall therefore now refer to them4 ,and1 first1 there is the suet--the fat of the ox--,russian tallow1 ,i believe1 employed in the manufacture of these dips1 which ,gay ,lussac1 or some one who entrusted him with his knowledge1 converted into that beautiful substance1 stearin1 which you see lying beside it4 ,a candle1 you know1 is not now a greasy thing like an ordinary tallow candle1 but a clean thing1 and you may almost scrape off and pulverise the drops which fall from it without soiling anything4 ,this is the process he adopted#b3--,the fat or tallow is first boiled with quick-lime1 and made into a soap1 and then the soap is decomposed by sulphuric acid1 which takes away the lime1 and leaves the fat re-arranged as stearic acid1 whilst a quantity of glycerin is produced at the same time4 ,glycerin--absolutely a sugar1 or a substance similar to sugar--comes out of the tallow in this chemical change4 ,the oil is then pressed out of it2 and you see here this series of pressed cakes1 shewing how beautifully the impurities are carried out by the oily part as the pressure goes on increasing1 and at last you have left that substance which is melted1 and cast into candles as here represented4 ,the candle ,i have in my hand is a stearin candle1 made of stearin from tallow in the way ,i have told you4 ,then here is a sperm candle1 which comes from the purified oil of the spermaceti whale4 ,here also are yellow bees-wax and refined bees-wax1 from which candles are made4 ,here1 too1 is that curious substance called paraffin1 and some paraffin candles made of paraffin obtained from the bogs of ,ireland4 ,i have here also a substance brought from ,japan1 since we have forced an entrance into that out-of-the-way place--a sort of wax which a kind friend has sent me1 and which forms a new material for the manufacture of candles4 ,and how are these candles made8 ,i have told you about dips1 and ,i will shew you how moulds are made4 ,let us imagine any of these candles to be made of materials which can be cast4 8,cast60 you say4 8,why1 a candle is a thing that melts2 and surely if you can melt it1 you can cast it40 ,not so4 ,it is wonderful1 in the progress of manufacture1 and in the consideration of the means best fitted to produce the required result1 how things turn up which one would not expect beforehand4 ,candles cannot always be cast4 ,a wax candle can never be cast4 ,it is made by a particular process1 which ,i can illustrate in a minute or two3 but ,i must not spend much time on it4 ,wax is a thing which1 burning so well1 and melting so easily in a candle1 cannot be cast4 ,however1 let us take a material that can be cast4 ,here is a frame1 with a number of moulds fastened in it4 ,the first thing to be done is to put a wick through them4 ,here is one--a plaited wick1 which does not require snuffing#c--supported by a little wire4 ,it goes to the bottom1 where it is pegged in--the little peg holding the cotton tight1 and stopping the aperture1 so that nothing fluid shall run out4 ,at the upper part there is a little bar placed across1 which stretches the cotton and holds it in the mould4 ,the tallow is then melted1 and the moulds are filled4 ,after a certain time1 when the moulds are cool1 the excess of tallow is poured off at one corner1 and then cleaned off altogether1 and the ends of the wick cut away4 ,the candles alone then remain in the mould1 and you have only to upset them1 as ,i am doing1 when out they tumble1 for the candles are made in the form of cones1 being narrower at the top than at the bottom2 so that what with their form and their own shrinking1 they only need a little shaking1 and out they fall4 ,in the same way are made these candles of stearin and of paraffin4 ,it is a curious thing to see how wax candles are made4 ,a lot of cottons are hung upon frames1 as you see here1 and covered with metal tags at the ends to keep the wax from covering the cotton in those places4 ,these are carried to a heater1 where the wax is melted4 ,as you see1 the frames can turn round2 and as they turn1 a man takes a vessel of wax and pours it first down one1 and then the next and the next1 and so on4 ,when he has gone once round1 if it is sufficiently cool1 he gives the first a second coat1 and so on until they are all of the required thickness4 ,when they have been thus clothed1 or fed1 or made up to that thickness1 they are taken off1 and placed elsewhere4 ,i have here1 by the kindness of ,mr4 ,field1 several specimens of these candles4 ,here is one only half-finished4 ,they are then taken down1 and well rolled upon a fine stone slab1 and the conical top is moulded by properly shaped tubes1 and the bottoms cut off and trimmed4 ,this is done so beautifully that they can make candles in this way weighing exactly four1 or six1 to the pound1 or any number they please4 ,we must not1 however1 take up more time about the mere manufacture1 but go a little further into the matter4 ,i have not yet referred you to luxuries in candles 7for there is such a thing as luxury in candles74 ,see how beautifully these are coloured3 you see here mauve1 magenta1 and all the chemical colours recently introduced1 applied to candles4 ,you observe1 also1 different forms employed4 ,here is a fluted pillar most beautifully shaped2 and ,i have also here some candles sent me by ,mr4 ,pearsall1 which are ornamented with designs upon them1 so that as they burn you have as it were a glowing sun above1 and a bouquet of flowers beneath4 ,all1 however1 that is fine and beautiful is not useful4 ,these fluted candles1 pretty as they are1 are bad candles2 they are bad because of their external shape4 ,nevertheless1 ,i shew you these specimens sent to me from kind friends on all sides1 that you may see what is done1 and what may be done in this or that direction2 although1 as ,i have said1 when we come to these refinements1 we are obliged to sacrifice a little in utility4 ,now1 as to the light of the candle4 ,we will light one or two1 and set them at work in the performance of their proper functions4 ,you observe a candle is a very different thing from a lamp4 ,with a lamp you take a little oil1 fill your vessel1 put in a little moss or some cotton prepared by artificial means1 and then light the top of the wick4 ,when the flame runs down the cotton to the oil1 it gets extinguished1 but it goes on burning in the part above4 ,now1 ,i have no doubt you will ask1 how is it that the oil1 which will not burn of itself1 gets up to the top of the cotton1 where it will burn8 ,we shall presently examine that2 but there is a much more wonderful thing about the burning of a candle than this4 ,you have here a solid substance with no vessel to contain it2 and how is it that this solid substance can get up to the place where the flame is8 ,how is it that this solid gets there1 it not being a fluid8 or1 when it is made a fluid1 then how is it that it keeps together8 ,this is a wonderful thing about a candle4 ,we have here a good deal of wind1 which will help us in some of our illustrations1 but tease us in others2 for the sake1 therefore1 of a little regularity1 and to simplify the matter1 ,i shall make a quiet flame--for who can study a subject when there are difficulties in the way not belonging to it8 ,here is a clever invention of some costermonger or street stander in the market-place for the shading of their candles on ,saturday nights1 when they are selling their greens1 or potatoes1 or fish4 ,i have very often admired it4 ,they put a lamp-glass round the candle1 supported on a kind of gallery1 which clasps it1 and it can be slipped up and down as required4 ,by the use of this lamp-glass1 employed in the same way1 you have a steady flame1 which you can look at1 and carefully examine1 as ,i hope you will do1 at home4 ,you see1 then1 in the first instance1 that a beautiful cup is formed4 ,as the air comes to the candle it moves upwards by the force of the current which the heat of the candle produces1 and it so cools all the sides of the wax1 tallow1 or fuel1 as to keep the edge much cooler than the part within2 the part within melts by the flame that runs down the wick as far as it can go before it is extinguished1 but the part on the outside does not melt4 ,if ,i made a current in one direction1 my cup would be lop-sided1 and the fluid would consequently run over1--for the same force of gravity which holds worlds together holds this fluid in a horizontal position1 and if the cup be not horizontal1 of course the fluid will run away in guttering4 ,you see1 therefore1 that the cup is formed by this beautifully regular ascending current of air playing upon all sides1 which keeps the exterior of the candle cool4 ,no fuel would serve for a candle which has not the property of giving this cup1 except such fuel as the ,irish bogwood1 where the material itself is like a sponge1 and holds its own fuel4 ,you see now why you would have had such a bad result if you were to burn these beautiful candles that ,i have shewn you1 which are irregular1 intermittent in their shape1 and cannot therefore have that nicely-formed edge to the cup which is the great beauty in a candle4 ,i hope you will now see that the perfection of a process--that is1 its utility--is the better point of beauty about it4 ,it is not the best looking thing1 but the best acting thing1 which is the most advantageous to us4 ,this good-looking candle is a bad burning one4 ,there will be a guttering round about it because of the irregularity of the stream of air and the badness of the cup which is formed thereby4 ,you may see some pretty examples 7and ,i trust you will notice these instances7 of the action of the ascending current when you have ,a little gutter run down the side of a candle1 making it thicker there than it is elsewhere4 ,as the candle goes on burning1 that keeps its place and forms a little pillar sticking up by the side1 because1 as it rises higher above the rest of the wax or fuel1 the air gets better round it1 and it is more cooled and better able to resist the action of the heat at a little distance4 ,now1 the greatest mistakes and faults with regard to candles1 as in many other things1 often bring with them instruction which we should not receive if they had not occurred4 ,we come here to be philosophers2 and ,i hope you will always remember that whenever a result happens1 especially if it be new1 you should say1 8,what is the cause8 ,why does it occur80 and you will in the course of time find out the reason4 ,then1 there is another point about these candles which will answer a question1--that is1 as to the way in which this fluid gets out of the cup1 up the wick1 and into the place of combustion4 ,you know that the flames on these burning wicks in candles made of bees-wax1 stearin1 or spermaceti1 do not run down to the wax or other matter1 and melt it all away1 but keep to their own right place4 ,they are fenced off from the fluid below1 and do not encroach on the cup at the sides4 ,i cannot imagine a more beautiful example than the condition of adjustment under which a candle makes one part subserve to the other to the very end of its action4 ,a combustible thing like that1 burning away gradually1 never being intruded upon by the flame1 is a very beautiful sight2 especially when you come to learn what a vigorous thing flame is--what power it has of destroying the wax itself when it gets hold of it1 and of disturbing its proper form if it come only too near4 ,but how does the flame get hold of the fuel8 ,there is a beautiful point about that--capillary attraction#d4 8,capillary attraction60 you say1--8the attraction of hairs40 ,well1 never mind the name3 it was given in old times1 before we had a good understanding of what the real power was4 ,it is by what is called capillary attraction that the fuel is conveyed to the part where combustion goes on1 and is deposited there1 not in a careless way1 but very beautifully in the very midst of the centre of action which takes place around it4 ,now1 ,i am going to give you one or two instances of capillary attraction4 ,it is that kind of action or attraction which makes two things that do not dissolve in each other still hold together4 ,when you wash your hands1 you wet them thoroughly2 you take a little soap to make the adhesion better1 and you find your hand remains wet4 ,this is by that kind of attraction of which ,i am about to speak4 ,and1 what is more1 if your hands are not soiled 7as they almost always are by the usages of life71 if you put your finger into a little warm water1 the water will creep a little way up the finger1 though you may not stop to examine it4 ,i have here a substance which is rather porous--a column of salt--and ,i will pour into the plate at the bottom1 not water1 as it appears1 but a saturated solution of salt which cannot absorb more2 so that the action which you see will not be due to its dissolving anything4 ,we may consider the plate to be the candle1 and the salt the wick1 and this solution the melted tallow4 7,i have coloured the fluid1 that you may see the action better47 ,you observe that1 now ,i pour in the fluid1 it rises and gradually creeps up the salt higher and higher2 and provided the column does not tumble over1 it will go to the top4 ,illustration3 ,fig4 #a4 ,if this blue solution were combustible1 and we were to place a wick at the top of the salt1 it would burn as it entered into the wick4 ,it is a most curious thing to see this kind of action taking place1 and to observe how singular some of the circumstances are about it4 ,when you wash your hands1 you take a towel to wipe off the water2 and it is by that kind of wetting1 or that kind of attraction which makes the towel become wet with water1 that the wick is made wet with the tallow4 ,i have known some careless boys and girls 7indeed1 ,i have known it happen to careful people as well7 who1 having washed their hands and wiped them with a towel1 have thrown the towel over the side of the basin1 and before long it has drawn all the water out of the basin and conveyed it to the floor1 because it happened to be thrown over the side in such a way as to serve the purpose of a syphon4#e ,that you may the better see the way in which the substances act one upon another1 ,i have here a vessel made of wire gauze filled with water1 and you may compare it in its action to the cotton in one respect1 or to a piece of calico in the other4 ,in fact1 wicks are sometimes made of a kind of wire gauze4 ,you will observe that this vessel is a porous thing2 for if ,i pour a little water on to the top1 it will run out at the bottom4 ,you would be puzzled for a good while if ,i asked you what the state of this vessel is1 what is inside it1 and why it is there8 ,the vessel is full of water1 and yet you see the water goes in and runs out as if it were empty4 ,in order to prove this to you1 ,i have only to empty it4 ,the reason is this1--the wire1 being once wetted1 remains wet2 the meshes are so small that the fluid is attracted so strongly from the one side to the other1 as to remain in the vessel although it is porous4 ,in like manner the particles of melted tallow ascend the cotton and get to the top2 other particles then follow by their mutual attraction for each other1 and as they reach the flame they are gradually burned4 ,here is another application of the same principle4 ,you see this bit of cane4 ,i have seen boys about the streets1 who are very anxious to appear like men1 take a piece of cane1 and light it and smoke it1 as an imitation of a cigar4 ,they are enabled to do so by the permeability of the cane in one direction1 and by its capillarity4 ,if ,i place this piece of cane on a plate containing some camphine 7which is very much like paraffin in its general character71 exactly in the same manner as the blue fluid rose through the salt will this fluid rise through the piece of cane4 ,there being no pores at the side1 the fluid cannot go in that direction1 but must pass through its length4 ,already the fluid is at the top of the cane3 now ,i can light it and make it serve as a candle4 ,the fluid has risen by the capillary attraction of the piece of cane1 just as it does through the cotton in the candle4 ,now1 the only reason why the candle does not burn all down the side of the wick is1 that the melted tallow extinguishes the flame4 ,you know that a candle1 if turned upside-down1 so as to allow the fuel to run upon the wick1 will be put out4 ,the reason is1 that the flame has not had time to make the fuel hot enough to burn1 as it does above1 where it is carried in small quantities into the wick1 and has all the effect of the heat exercised upon it4 ,there is another condition which you must learn as regards the candle1 without which you would not be able fully to understand the philosophy of it1 and that is the vaporous condition of the fuel4 ,in order that you may understand that1 let me shew you a very pretty1 but very common-place experiment4 ,if you blow a candle out cleverly1 you will see the vapour rise from it4 ,you have1 ,i know1 often smelt the vapour of a blown-out candle--and a very bad smell it is2 but if you blow it out cleverly1 you will be able to see pretty well the vapour into which this solid matter is transformed4 ,i will blow out one of these candles in such a way as not to disturb the air around it1 by the continuing action of my breath2 and now1 if ,i hold a lighted taper two or three inches from the wick1 you will observe a train of fire going through the air till it reaches the candle4 ,i am obliged to be quick and ready1 because1 if ,i allow the vapour time to cool1 it becomes condensed into a liquid or solid1 or the stream of combustible matter gets disturbed4 ,now1 as to the shape or form of the flame4 ,it concerns us much to know about the condition which the matter of the candle finally assumes at the top of the wick--where you have such beauty and brightness as nothing but combustion or flame can produce4 ,illustration3 ,fig4 #b4 ,you have the glittering beauty of gold and silver1 and the still higher lustre of jewels1 like the ruby and diamond2 but none of these rival the brilliancy and beauty of flame4 ,what diamond can shine like flame8 ,it owes its lustre at night-time to the very flame shining upon it4 ,the flame shines in darkness1 but the light which the diamond has is as nothing until the flame shine upon it1 when it is brilliant again4 ,the candle alone shines by itself1 and for itself1 or for those who have arranged the materials4 ,now1 let us look a little at the form of the flame as you see it under the glass shade4 ,it is steady and equal2 and its general form is that which is represented in the diagram1 varying with atmospheric disturbances1 and also varying according to the size of the candle4 ,it is a bright oblong--brighter at the top than towards the bottom--with the wick in the middle1 and besides the wick in the middle1 certain darker parts towards the bottom1 where the ignition is not so perfect as in the part above4 ,illustration3 ,fig4 #c4 ,i have a drawing here1 sketched many years ago by ,hooke1 when he made his investigations4 ,it is the drawing of the flame of a lamp1 but it will apply to the flame of a candle4 ,the cup of the candle is the vessel or lamp1 the melted spermaceti is the oil1 and the wick is common to both4 ,upon that he sets this little flame1 and then he represents what is true--a certain quantity of matter rising about it which you do not see1 and which1 if you have not been here before1 or are not familiar with the subject1 you will not know of4 ,he has here represented the parts of the surrounding atmosphere that are very essential to the flame1 and that are always present with it4 ,there is a current formed1 which draws the flame out--for the flame which you see is really drawn out by the current1 and drawn upward to a great height--just as ,hooke has here shewn you by that prolongation of the current in the diagram4 ,you may see this by taking a lighted candle1 and putting it in the sun so as to get its shadow thrown on a piece of paper4 ,how remarkable it is that that thing which is light enough to produce shadows of other objects1 can be made to throw its own shadow on a piece of white paper or card1 so that you can actually see streaming round the flame something which is not part of the flame1 but is ascending and drawing the flame upwards4 ,now1 ,i am going to imitate the sunlight1 by applying the voltaic battery to the electric lamp4 ,you now see our sun1 and its great luminosity2 and by placing a candle between it and the screen1 we get the shadow of the flame4 ,illustration3 ,fig4 #d4 ,you observe the shadow of the candle and of the wick2 then there is a darkish part1 as represented in the diagram1 and then a part which is more distinct4 ,curiously enough1 however1 what we see in the shadow as the darkest part of the flame is1 in reality1 the brightest part2 and here you see streaming upwards the ascending current of hot air1 as shewn by ,hooke1 which draws out the flame1 supplies it with air1 and cools the sides of the cup of melted fuel4 ,i can give you here a little further illustration1 for the purpose of shewing you how flame goes up or down2 according to the current4 ,i have here a flame--it is not a candle-flame--but you can1 no doubt1 by this time1 generalise enough to be able to compare one thing with another4 ,what ,i am about to do is to change the ascending current that takes the flame upwards into a descending current4 ,this ,i can easily do by the little apparatus you see before me4 ,the flame1 as ,i have said1 is not a candle flame1 but it is produced by alcohol1 so that it shall not smoke too much4 ,i will also colour the flame with another substance#f1 so that you may trace its course2 for with the spirit alone you could hardly see well enough to have the opportunity of tracing its direction4 ,by lighting this spirit-of-wine1 we have then a flame produced2 and you observe that when held in the air1 it naturally goes upwards4 ,illustration3 ,fig4 #e ,you understand now easily enough why flames go up under ordinary circumstances--it is because of the draught of air by which the combustion is formed4 ,but now1 by blowing the flame down1 you see ,i am enabled to make it go downwards into this little chimney--the direction of the current being changed4 ,before we have concluded this course of lectures1 we shall shew you a lamp in which the flame goes up and the smoke goes down1 or the flame goes down and the smoke goes up4 ,you see1 then1 that we have the power in this way of varying the flame in different directions4 ,there are now some other points that ,i must bring before you4 ,many of the flames you see here vary very much in their shape by the currents of air blowing around them in different directions2 but we can1 if we like1 make flames so that they will look like fixtures1 and we can photograph them--indeed1 we have to photograph them--so that they become fixed to us1 if we wish to find out everything concerning them4 ,that1 however1 is not the only thing ,i wish to mention4 ,if ,i take a flame sufficiently large1 it does not keep that homogeneous1 that uniform condition of shape1 but it breaks out with a power of life which is quite wonderful4 ,i am about to use another kind of fuel1 but one which is truly and fairly a representative of the wax or tallow of a candle4 ,i have here a large ball of cotton1 which will serve as a wick4 ,and1 now that ,i have immersed it in spirit and applied a light to it1 in what way does it differ from an ordinary candle8 ,why1 it differs very much in one respect1 that we have a vivacity and power about it1 a beauty and a life entirely different from the light presented by a candle4 ,you see those fine tongues of flame rising up4 ,you have the same general disposition of the mass of the flame from below upwards2 but1 in addition to that1 you have this remarkable breaking out into tongues which you do not perceive in the case of a candle4 ,now1 why is this8 ,i must explain it to you1 because when you understand that perfectly1 you will be able to follow me better in what ,i have to say hereafter4 ,i suppose some here will have made for themselves the experiment ,i am going to shew you4 ,am ,i right in supposing that anybody here has played at snapdragon8 ,i do not know a more beautiful illustration of the philosophy of flame1 as to a certain part of its history1 than the game of snapdragon4 ,first1 here is the dish2 and let me say1 that when you play snapdragon properly1 you ought to have the dish well-warmed2 you ought also to have warm plums and warm brandy1 which1 however1 ,i have not got4 ,when you have put the spirit into the dish1 you have the cup and the fuel2 and are not the raisins acting like the wicks8 ,i now throw the plums into the dish1 and light the spirit1 and you see those beautiful tongues of flame that ,i refer to4 ,you have the air creeping in over the edge of the dish forming these tongues4 ,why8 ,because1 through the force of the current and the irregularity of the action of the flame1 it cannot flow in one uniform stream4 ,the air flows in so irregularly that you have what would otherwise be a single image1 broken up into a variety of forms1 and each of these little tongues has an independent existence of its own4 ,indeed1 ,i might say1 you have here a multitude of independent candles4 ,you must not imagine1 because you see these tongues all at once1 that the flame is of this particular shape4 ,a flame of that shape is never so at any one time4 ,never is a body of flame1 like that which you just saw rising from the ball1 of the shape it appears to you4 ,it consists of a multitude of different shapes1 succeeding each other so fast that the eye is only able to take cognisance of them all at once4 ,in former times1 ,i purposely analysed a flame of that general character1 and the diagram shews you the different parts of which it is composed4 ,they do not occur all at once3 it is only because we see these shapes in such rapid succession1 that they seem to us to exist all at one time4 ,illustration3 ,fig4 #f4 ,it is too bad that we have not got further than my game of snapdragon2 but we must not1 under any circumstances1 keep you beyond your time4 ,it will be a lesson to me in future to hold you more strictly to the philosophy of the thing1 than to take up your time so much with these illustrations4 ,,lecture ,,ii4 ,a ,,candle3 ,,brightness ,,of ,,the ,,flame--,,air ,,necessary ,,for ,,combustion--,,production ,,of ,,water4 ,we were occupied the last time we met in considering the general character and arrangement as regards the fluid portion of a candle1 and the way in which that fluid got into the place of combustion4 ,you see1 when we have a candle burning fairly in a regular1 steady atmosphere1 it will have a shape something like the one shewn in the diagram1 and will look pretty uniform1 although very curious in its character4 ,and now1 ,i have to ask your attention to the means by which we are enabled to ascertain what happens in any particular part of the flame--why it happens1 what it does in happening1 and where1 after all1 the whole candle goes to3 because1 as you know very well1 a candle being brought before us and burned1 disappears1 if burned properly1 without the least trace of dirt in the candlestick--and this is a very curious circumstance4 ,in order1 then1 to examine this candle carefully1 ,i have arranged certain apparatus1 the use of which you will see as ,i go on4 ,here is a candle3 ,i am about to put the end of this glass tube into the middle of the flame--into that part which old ,hooke has represented in the diagram as being rather dark1 and which you can see at any time1 if you will look at a candle carefully1 without blowing it about4 ,we will examine this dark part first4 ,illustration3 ,fig4 #g4 ,now1 ,i take this bent glass tube1 and introduce one end into that part of the flame1 and you see at once that something is coming from the flame1 out at the other end of the tube2 and if ,i put a flask there1 and leave it for a little while1 you will see that something from the middle part of the flame is gradually drawn out1 and goes through the tube and into that flask1 and there behaves very differently from what it does in the open air4 ,it not only escapes from the end of the tube1 but falls down to the bottom of the flask like a heavy substance1 as indeed it is4 ,we find that this is the wax of the candle made into a vaporous fluid--not a gas4 7,you must learn the difference between a gas and a vapour3 a gas remains permanent1 a vapour is something that will condense47 ,if you blow out a candle1 you perceive a very nasty smell1 resulting from the condensation of this vapour4 ,that is very different from what you have outside the flame2 and1 in order to make that more clear to you1 ,i am about to produce and set fire to a larger portion of this vapour--for what we have in the small way in a candle1 to understand thoroughly1 we must1 as philosophers1 produce in a larger way1 if needful1 that we may examine the different parts4 ,and now ,mr4 ,anderson will give me a source of heat1 and ,i am about to shew you what that vapour is4 ,here is some wax in a glass flask1 and ,i am going to make it hot1 as the inside of that candle-flame is hot1 and the matter about the wick is hot4 ,the ,lecturer placed some wax in a glass flask1 and heated it over a lamp4 ,now1 ,i dare say that is hot enough for me4 ,you see that the wax ,i put in it has become fluid1 and there is a little smoke coming from it4 ,we shall very soon have the vapour rising up4 ,i will make it still hotter1 and now we get more of it1 so that ,i can actually pour the vapour out of the flask into that basin1 and set it on fire there4 ,this1 then1 is exactly the same kind of vapour as we have in the middle of the candle2 and that you may be sure this is the case1 let us try whether we have not got here1 in this flask1 a real combustible vapour out of the middle of the candle4 ,taking the flask into which the tube from the candle proceeded1 and introducing a lighted taper4 ,see how it burns4 ,now1 this is the vapour from the middle of the candle1 produced by its own heat2 and that is one of the first things you have to consider with respect to the progress of the wax in the course of its combustion1 and as regards the changes it undergoes4 ,i will arrange another tube carefully in the flame1 and ,i should not wonder if we were able1 by a little care1 to get that vapour to pass through the tube to the other extremity1 where we will light it1 and obtain absolutely the flame of the candle at a place distant from it4 ,now1 look at that4 ,is not that a very pretty experiment8 ,talk about laying on gas--why1 we can actually lay on a candle6 ,and you see from this that there are clearly two different kinds of action--one the production of the vapour1 and the other the combustion of it--both of which take place in particular parts of the candle4 ,illustration3 ,fig4 #h ,i shall get no vapour from that part which is already burnt4 ,if ,i raise the tube 7fig4 #g7 to the upper part of the flame1 so soon as the vapour has been swept out1 what comes away will be no longer combustible3 ,it is already burned4 ,how burned8 ,why1 burned thus3--,in the middle of the flame1 where the wick is1 there is this combustible vapour2 on the outside of the flame is the air which we shall find necessary for the burning of the candle2 between the two1 intense chemical action takes place1 whereby the air and the fuel act upon each other1 and at the very same time that we obtain light the vapour inside is destroyed4 ,if you examine where the heat of a candle is1 you will find it very curiously arranged4 ,suppose ,i take this candle1 and hold a piece of paper close upon the flame1 where is the heat of that flame8 ,do you not see that it is not in the inside8 ,it is in a ring1 exactly in the place where ,i told you the chemical action was2 and even in my irregular mode of making the experiment1 if there is not too much disturbance1 there will always be a ring4 ,this is a good experiment for you to make at home4 ,take a strip of paper1 have the air in the room quiet1 and put the piece of paper right across the middle of the flame 7,i must not talk while ,i make the experiment71 and you will find that it is burnt in two places1 and that it is not burnt1 or very little so1 in the middle2 and when you have tried the experiment once or twice1 so as to make it nicely1 you will be very interested to see where the heat is1 and to find that it is where the air and the fuel come together4 ,this is most important for us as we proceed with our subject4 ,air is absolutely necessary for combustion2 and1 what is more1 ,i must have you understand that fresh air is necessary1 or else we should be imperfect in our reasoning and our experiments4 ,here is a jar of air4 ,i place it over a candle1 and it burns very nicely in it at first1 shewing that what ,i have said about it is true2 but there will soon be a change4 ,see how the flame is drawing upwards1 presently fading1 and at last going out4 ,and going out1 why8 ,not because it wants air merely1 for the jar is as full now as it was before2 but it wants pure1 fresh air4 ,the jar is full of air1 partly changed1 partly not changed2 but it does not contain sufficient of the fresh air which is necessary for the combustion of a candle4 ,these are all points which we1 as young chemists1 have to gather up2 and if we look a little more closely into this kind of action1 we shall find certain steps of reasoning extremely interesting4 ,for instance1 here is the oil-lamp ,i shewed you--an excellent lamp for our experiments--the old ,argand lamp4 ,i now make it like a candle obstructing the passage of air into the centre of the flame2 there is the cotton2 there is the oil rising up it2 and there is the conical flame4 ,it burns poorly1 because there is a partial restraint of air4 ,i have allowed no air to get to it1 save round the outside of the flame1 and it does not burn well4 ,i cannot admit more air from the outside1 because the wick is large2 but if1 as ,argand did so cleverly1 ,i open a passage to the middle of the flame1 and so let air come in there1 you will see how much more beautifully it burns4 ,if ,i shut the air off1 look how it smokes2 and why8 ,we have now some very interesting points to study4 ,we have the case of the combustion of a candle2 we have the case of a candle being put out by the want of air2 and we have now the case of imperfect combustion2 and this is to us so interesting1 that ,i want you to understand it as thoroughly as you do the case of a candle burning in its best possible manner4 ,i will now make a great flame1 because we need the largest possible illustrations4 ,here is a larger wick burning turpentine on a ball of cotton4 ,all these things are the same as candles1 after all4 ,if we have larger wicks1 we must have a larger supply of air1 or we shall have less perfect combustion4 ,look now at this black substance going up into the atmosphere2 there is a regular stream of it4 ,i have provided means to carry off the imperfectly burned part1 lest it should annoy you4 ,look at the soots that fly off from the flame3 see what an imperfect combustion it is1 because it cannot get enough air4 ,what1 then1 is happening8 ,why1 certain things which are necessary to the combustion of a candle are absent1 and very bad results are accordingly produced2 but we see what happens to a candle when it is burnt in a pure and proper state of air4 ,at the time when ,i shewed you this charring by the ring of flame on the one side of the paper1 ,i might have also shewn you1 by turning to the other side1 that the burning of a candle produces the same kind of soot--charcoal or carbon4 ,but1 before ,i shew that1 let me explain to you--as it is quite necessary for our purpose--that1 though ,i take a candle and give you1 as the general result1 its combustion in the form of a flame1 we must see whether combustion is always in this condition1 or whether there are other conditions of flame2 and we shall soon discover that there are1 and that they are most important to us4 ,i think1 perhaps1 the best illustration of such a point to us1 as juveniles1 is to shew the result of strong contrast4 ,here is a little gunpowder4 ,you know that gunpowder burns with flame--we may fairly call it flame4 ,it contains carbon and other materials1 which altogether cause it to burn with a flame4 ,and here is some pulverised iron1 or iron filings4 ,now1 ,i purpose burning these two things together4 ,i have a little mortar in which ,i will mix them4 7,before ,i go into these experiments1 let me hope that none of you1 by trying to repeat them1 for fun's sake1 will do any harm4 ,these things may all be very properly used if you take care2 but without that1 much mischief will be done47 ,well1 then1 here is a little gunpowder1 which ,i put at the bottom of that little wooden vessel1 and mix the iron filings up with it1 my object being to make the gunpowder set fire to the filings and burn them in the air1 and thereby shew the difference between substances burning with flame and not with flame4 ,here is the mixture2 and when ,i set fire to it1 you must watch the combustion1 and you will see that it is of two kinds4 ,you will see the gunpowder burning with a flame1 and the filings thrown up4 ,you will see them burning too1 but without the production of flame4 ,they will each burn separately4 ,the ,lecturer then ignited the mixture4 ,there is the gunpowder1 which burns with a flame2 and there are the filings--they burn with a different kind of combustion4 ,you see1 then1 these two great distinctions2 and upon these differences depend all the utility and all the beauty of flame which we use for the purpose of giving out light4 ,when we use oil1 or gas1 or candle1 for the purpose of illumination1 their fitness all depends upon these different kinds of combustion4 ,there are such curious conditions of flame1 that it requires some cleverness and nicety of discrimination to distinguish the kinds of combustion one from another4 ,for instance1 here is a powder which is very combustible1 consisting1 as you see1 of separate little particles4 ,it is called lycopodium#g1 and each of these particles can produce a vapour1 and produce its own flame2 but1 to see them burning1 you would imagine it was all one flame4 ,i will now set fire to a quantity1 and you will see the effect4 ,we saw a cloud of flame1 apparently in one body2 but that rushing noise referring to the sound produced by the burning was a proof that the combustion was not a continuous or regular one4 ,this is the lightning of the pantomimes1 and a very good imitation4 ,the experiment was twice repeated by blowing lycopodium from a glass tube through a spirit-flame4 ,this is not an example of combustion like that of the filings ,i have been speaking of1 to which we must now return4 ,suppose ,i take a candle1 and examine that part of it which appears brightest to our eyes4 ,why1 there ,i get these black particles1 which already you have seen many times evolved from the flame1 and which ,i am now about to evolve in a different way4 ,i will take this candle and clear away the gutterage1 which occurs by reason of the currents of air2 and if ,i now arrange a glass tube so as just to dip into this luminous part1 as in our first experiment1 only higher1 you see the result4 ,in place of having the same white vapour that you had before1 you will now have a black vapour4 ,there it goes1 as black as ink4 ,it is certainly very different from the white vapour2 and when we put a light to it1 we shall find that it does not burn1 but that it puts the light out4 ,well1 these particles1 as ,i said before1 are just the smoke of the candle2 and this brings to mind that old employment which ,dean ,swift recommended to servants for their amusement1 namely1 writing on the ceiling of a room with a candle4 ,but what is that black substance8 ,why1 it is the same carbon which exists in the candle4 ,how comes it out of the candle8 ,it evidently existed in the candle1 or else we should not have had it here4 ,and now ,i want you to follow me in this explanation4 ,you would hardly think that all those substances which fly about ,london1 in the form of soots and blacks1 are the very beauty and life of the flame1 and which are burned in it as those iron filings were burned here4 ,here is a piece of wire gauze1 which will not let the flame go through it2 and ,i think you will see1 almost immediately1 that when ,i bring it low enough to touch that part of the flame which is otherwise so bright1 that it quells and quenches it at once1 and allows a volume of smoke to rise up4 ,i want you now to follow me in this point1--that whenever a substance burns1 as the iron filings burnt in the flame of gunpowder1 without assuming the vaporous state 7whether it becomes liquid or remains solid71 it becomes exceedingly luminous4 ,i have here taken three or four examples apart from the candle1 on purpose to illustrate this point to you2 because what ,i have to say is applicable to all substances1 whether they burn or whether they do not burn1--that they are exceedingly bright if they retain their solid state1 and that it is to this presence of solid particles in the candle-flame that it owes its brilliancy4 ,here is a platinum-wire1 a body which does not change by heat4 ,if ,i heat it in this flame1 see how exceedingly luminous it becomes4 ,i will make the flame dim1 for the purpose of giving a little light only1 and yet you will see that the heat which it can give to that platinum-wire1 though far less than the heat it has itself1 is able to raise the platinum-wire to a far higher state of effulgence4 ,this flame has carbon in it2 but ,i will take one that has no carbon in it4 ,there is a material1 a kind of fuel--a vapour1 or gas1 whichever you like to call it--in that vessel1 and it has no solid particles in it2 so ,i take that because it is an example of flame itself burning without any solid matter whatever2 and if ,i now put this solid substance in it1 you see what an intense heat it has1 and how brightly it causes the solid body to glow4 ,this is the pipe through which we convey this particular gas1 which we call hydrogen1 and which you shall know all about next time we meet4 ,and here is a substance called oxygen1 by means of which this hydrogen can burn2 and although we produce1 by their mixture1 far greater heat#h than you can obtain from the candle1 yet there is very little light4 ,if1 however1 ,i take a solid substance1 and put that into it1 we produce an intense light ,if ,i take a piece of lime1 a substance which will not burn1 and which will not vaporise by the heat 7and because it does not vaporise1 remains solid1 and remains heated71 you will soon observe what happens as to its glowing4 ,i have here a most intense heat1 produced by the burning of hydrogen in contact with the oxygen2 but there is as yet very little light--not for want of heat1 but for want of particles which can retain their solid state2 but when ,i hold this piece of lime in the flame of the hydrogen as it burns in the oxygen1 see how it glows6 ,this is the glorious lime-light1 which rivals the voltaic-light1 and which is almost equal to sunlight4 ,i have here a piece of carbon or charcoal1 which will burn and give us light exactly in the same manner as if it were burnt as part of a candle4 ,the heat that is in the flame of a candle decomposes the vapour of the wax1 and sets free the carbon particles--they rise up heated and glowing as this now glows1 and then enter into the air4 ,but the particles when burnt never pass off from a candle in the form of carbon4 ,they go off into the air as a perfectly invisible substance1 about which we shall know hereafter4 ,is it not beautiful to think that such a process is going on1 and that such a dirty thing as charcoal can become so incandescent8 ,you see it comes to this--that all bright flames contain these solid particles2 all things that burn and produce solid particles1 either during the time they are burning1 as in the candle1 or immediately after being burnt1 as in the case of the gunpowder and iron-filings1--all these things give us this glorious and beautiful light4 ,i will give you a few illustrations4 ,here is a piece of phosphorus1 which burns with a bright flame4 ,very well2 we may now conclude that phosphorus will produce1 either at the moment that it is burning or afterwards1 these solid particles4 ,here is the phosphorus lighted1 and ,i cover it over with this glass for the purpose of keeping in what is produced4 ,what is all that smoke8 ,that smoke consists of those very particles which are produced by the combustion of the phosphorus4 ,here1 again1 are two substances4 ,this is chlorate of potassa1 and this other sulphuret of antimony4 ,i shall mix these together a little1 and then they may be burnt in many ways4 ,i shall touch them with a drop of sulphuric acid1 for the purpose of giving you an illustration of chemical action1 and they will instantly burn#i4 ,the ,lecturer then ignited the mixture by means of sulphuric acid4 ,now1 from the appearance of things1 you can judge for yourselves whether they produce solid matter in burning4 ,i have given you the train of reasoning which will enable you to say whether they do or do not2 for what is this bright flame but the solid particles passing off8 ,illustration3 ,fig4 #i4 ,mr4 ,anderson has in the furnace a very hot crucible1--,i am about to throw into it some zinc filings1 and they will burn with a flame like gunpowder4 ,i make this experiment because you can make it well at home4 ,now1 ,i want you to see what will be the result of the combustion of this zinc4 ,here it is burning--burning beautifully like a candle1 ,i may say4 ,but what is all that smoke1 and what are those little clouds of wool which will come to you if you cannot come to them1 and make themselves sensible to you in the form of the old philosophic wool1 as it was called8 ,we shall have left in that crucible1 also1 a quantity of this woolly matter4 ,but ,i will take a piece of this same zinc and make an experiment a little more closely at home1 as it were4 ,you will have here the same thing happening4 ,here is the piece of zinc1 there pointing to a jet of hydrogen is the furnace1 and we will set to work and try and burn the metal4 ,it glows1 you see3 there is the combustion1 and there is the white substance into which it burns4 ,and so1 if ,i take that flame of hydrogen as the representative of a candle1 and shew you a substance like zinc burning in the flame1 you will see that it was merely during the action of combustion that this substance glowed--while it was kept hot2 and if ,i take a flame of hydrogen1 and put this white substance from the zinc into it1 look how beautifully it glows1 and just because it is a solid substance4 ,i will now take such a flame as ,i had a moment since1 and set free from it the particles of carbon4 ,here is some camphine1 which will burn with a smoke2 but if ,i send these particles of smoke through this pipe into the hydrogen flame1 you will see they will burn and become luminous1 because we heat them a second time4 ,there they are4 ,those are the particles of carbon re-ignited a second time4 ,they are those particles which you can easily see by holding a piece of paper behind them1 and which1 whilst they are in the flame1 are ignited by the heat produced1 and1 when so ignited1 produce this brightness4 ,when the particles are not separated1 you get no brightness4 ,the flame of coal-gas owes its brightness to the separation1 during combustion1 of these particles of carbon1 which are equally in that as in a candle4 ,i can very quickly alter that arrangement4 ,here1 for instance1 is a bright flame of gas4 ,supposing ,i add so much air to the flame as to cause it all to burn before those particles are set free1 ,i shall not have this brightness2 and ,i can do that in this way3--,if ,i place over the jet this wire-gauze cap1 as you see1 and then light the gas over it1 it burns with a non-luminous flame1 owing to its having plenty of air mixed with it before it burns2 and if ,i raise the gauze1 you see it does not burn below#aj4 ,there is plenty of carbon in the gas2 but1 because the atmosphere can get to it1 and mix with it before it burns1 you see how pale and blue the flame is4 ,and if ,i blow upon a bright gas-flame1 so as to consume all this carbon before it gets heated to the glowing point1 it will also burn blue3 ,the ,lecturer illustrated his remarks by blowing on the gas-light4 ,the only reason why ,i have not the same bright light when ,i thus blow upon the flame is1 that the carbon meets with sufficient air to burn it before it gets separated in the flame in a free state4 ,the difference is solely due to the solid particles not being separated before the gas is burnt4 ,you observe that there are certain products as the result of the combustion of a candle1 and that of these products one portion may be considered as charcoal1 or soot2 that charcoal1 when afterwards burnt1 produces some other product2 and it concerns us very much now to ascertain what that other product is4 ,we shewed that something was going away2 and ,i want you now to understand how much is going up into the air2 and for that purpose we will have combustion on a little larger scale4 ,from that candle ascends heated air1 and two or three experiments will shew you the ascending current2 but1 in order to give you a notion of the quantity of matter which ascends in this way1 ,i will make an experiment by which ,i shall try to imprison some of the products of this combustion4 ,for this purpose ,i have here what boys call a fire-balloon4 ,i use this fire-balloon merely as a sort of measure of the result of the combustion we are considering2 and ,i am about to make a flame in such an easy and simple manner as shall best serve my present purpose4 ,this plate shall be the 8cup10 we will so say1 of the candle2 this spirit shall be our fuel2 and ,i am about to place this chimney over it1 because it is better for me to do so than to let things proceed at random4 ,illustration3 ,fig4 #aj4 ,mr4 ,anderson will now light the fuel1 and here at the top we shall get the results of the combustion4 ,what we get at the top of that tube is exactly the same1 generally speaking1 as you get from the combustion of a candle2 but we do not get a luminous flame here1 because we use a substance which is feeble in carbon4 ,i am about to put this balloon--not into action1 because that is not my object--but to shew you the effect which results from the action of those products which arise from the candle1 as they arise here from the furnace4 ,the balloon was held over the chimney1 when it immediately commenced to fill4 ,you see how it is disposed to ascend2 but we must not let it up1 because it might come in contact with those upper gas-lights1 and that would be very inconvenient4 ,the upper gas-lights were turned out1 at the request of the ,lecturer1 and the balloon was allowed to ascend4 ,does not that shew you what a large bulk of matter is being evolved8 ,now1 there is going through this tube placing a large glass tube over a candle all the products of that candle1 and you will presently see that the tube will become quite opaque4 ,suppose ,i take another candle1 and place it under a jar1 and then put a light on the other side1 just to shew you what is going on4 ,you see that the sides of the jar become cloudy1 and the light begins to burn feebly4 ,it is the products1 you see1 which make the light so dim1 and this is the same thing which makes the sides of the jar so opaque4 ,if you go home and take a spoon that has been in the cold air1 and hold it over a candle--not so as to soot it--you will find that it becomes dim1 just as that jar is dim4 ,if you can get a silver dish1 or something of that kind1 you will make the experiment still better4 ,and now1 just to carry your thoughts forward to the time we shall next meet1 let me tell you that it is water which causes the dimness2 and when we next meet4 ,i will shew you that we can make it1 without difficulty1 assume the form of a liquid4 ,,lecture ,,iii4 ,,products3 ,,water ,,from ,,the ,,combustion--,,nature ,,of ,,water--,a ,,compound--,,hydrogen4 ,i dare say you will remember that when we parted we had just mentioned the word 8products0 from the candle4 ,for when a candle burns we found we were able1 by nice adjustment1 to get various products from it4 ,there was one substance which was not obtained when the candle was burning properly1 which was charcoal or smoke2 and there was some other substance that went upwards from the flame which did not appear as smoke1 but took some other form1 and made part of that general current which1 ascending from the candle upwards1 becomes invisible1 and escapes4 ,there were also other products to mention4 ,you remember that in that rising current having its origin at the candle1 we found that one part was condensable against a cold spoon1 or against a clean plate1 or any other cold thing1 and another part was incondensable4 ,we will first take the condensable part1 and examine it2 and1 strange to say1 we find that that part of the product is just water--nothing but water4 ,on the last occasion ,i spoke of it incidentally1 merely saying that water was produced among the condensable products of the candle2 but to-day ,i wish to draw your attention to water1 that we may examine it carefully1 especially in relation to this subject1 and also with respect to its general existence on the surface of the globe4 ,now1 having previously arranged an experiment for the purpose of condensing water from the products of the candle1 my next point will be to shew you this water2 and perhaps one of the best means that ,i can adopt for shewing its presence to so many at once1 is to exhibit a very visible action of water1 and then to apply that test to what is collected as a drop at the bottom of that vessel4 ,i have here a chemical substance1 discovered by ,sir ,humphrey ,davy1 which has a very energetic action upon water1 which ,i shall use as a test of the presence of water4 ,if ,i take a little piece of it--it is called potassium1 as coming from potash1--if ,i take a little piece of it1 and throw it into that basin1 you see how it shews the presence of water by lighting up and floating about1 burning with a violent flame4 ,i am now going to take away the candle which has been burning beneath the vessel containing ice and salt1 and you see a drop of water--a condensed product of the candle--hanging from under the surface of the dish4 ,illustration3 ,fig4 #aa4 ,i will shew you that potassium has the same action upon it as upon the water in that basin in the experiment we have just tried4 ,see1 it takes fire1 and burns in just the same manner4 ,i will take another drop upon this glass slab1 and when ,i put the potassium on to it1 you see at once1 from its taking fire1 that there is water present4 ,now1 that water was produced by the candle4 ,in the same manner1 if ,i put this spirit-lamp under that jar1 you will soon see the latter become damp1 from the dew which is deposited upon it--that dew being the result of combustion2 and ,i have no doubt you will shortly see by the drops of water which fall upon the paper below1 that there is a good deal of water produced from the combustion of the lamp4 ,i will let it remain1 and you can afterwards see how much water has been collected4 ,so1 if ,i take a gas-lamp1 and put any cooling arrangement over it1 ,i shall get water--water being likewise produced from the combustion of gas4 ,here1 in this bottle1 is a quantity of water--perfectly pure1 distilled water1 produced from the combustion of a gas-lamp--in no point different from the water that you distil from the river1 or ocean1 or spring1 but exactly the same thing4 ,water is one individual thing--it never changes4 ,we can add to it by careful adjustment1 for a little while1 or we can take it apart1 and get other things from it2 but water1 as water1 remains always the same1 either in a solid1 liquid1 or fluid state4 ,here1 again holding another bottle1 is some water produced by the combustion of an oil-lamp4 ,a pint of oil1 when burnt fairly and properly1 produces rather more than a pint of water4 ,here1 again1 is some water1 produced by a rather long experiment from a wax candle4 ,and so we can go on with almost all combustible substances1 and find that if they burn with a flame1 as a candle1 they produce water4 ,you may make these experiments yourselves4 ,the head of a poker is a very good thing to try with1 and if it remains cold long enough over the candle1 you may get water condensed in drops on it2 or a spoon or ladle1 or anything else may be used1 provided it be clean1 and can carry off the heat1 and so condense the water4 ,and now--to go into the history of this wonderful production of water from combustibles1 and by combustion--,i must first of all tell you that this water may exist in different conditions2 and although you may now be acquainted with all its forms1 they still require us to give a little attention to them for the present1 so that we may perceive how the water1 whilst it goes through its ,protean changes1 is entirely and absolutely the same thing1 whether it is produced from a candle1 by combustion1 or from the rivers or ocean4 ,first of all1 water1 when at the coldest1 is ice4 ,now1 we philosophers--,i hope that ,i may class you and myself together in this case--speak of water as water1 whether it be in its solid1 or liquid1 or gaseous state1--we speak of it chemically as water4 ,water is a thing compounded of two substances1 one of which we have derived from the candle1 and the other we shall find elsewhere4 ,water may occur as ice2 and you have had most excellent opportunities lately of seeing this4 ,ice changes back into water--for we had on our last ,sabbath a strong instance of this change1 by the sad catastrophe which occurred in our own house1 as well as in the houses of many of our friends1--ice changes back into water when the temperature is raised3 water also changes into steam when it is warmed enough4 ,the water which we have here before us is in its densest state#aa1 and although it changes in weight1 in condition1 in form1 and in many other qualities1 it still is water2 and whether we alter it into ice by cooling1 or whether we change it into steam by heat1 it increases in volume1--in the one case very strangely and powerfully1 and in the other case very largely and wonderfully4 ,for instance1 ,i will now take this tin cylinder1 and pour a little water into it2 and seeing how much water ,i pour in1 you may easily estimate for yourselves how high it will rise in the vessel3 it will cover the bottom about two inches4 ,i am now about to convert the water into steam1 for the purpose of shewing to you the different volumes which water occupies in its different states of water and steam4 ,let us now take the case of water changing into ice3 we can effect that by cooling it in a mixture of salt and pounded ice#ab2 and ,i shall do so to shew you the expansion of water into a thing of larger bulk when it is so changed4 ,these bottles holding one are made of strong cast iron1 very strong and very thick--,i suppose they are the third of an inch in thickness2 they are very carefully filled with water1 so as to exclude all air1 and then they are screwed down tight4 ,we shall see that when we freeze the water in these iron vessels1 they will not be able to hold the ice1 and the expansion within them will break them in pieces as these pointing to some fragments are broken1 which have been bottles of exactly the same kind4 ,i am about to put these two bottles into that mixture of ice and salt1 for the purpose of shewing that when water becomes ice1 it changes in volume in this extraordinary way4 ,in the mean time look at the change which has taken place in the water to which we have applied heat--it is losing its fluid state4 ,you may tell this by two or three circumstances4 ,i have covered the mouth of this glass flask1 in which water is boiling1 with a watch-glass4 ,do you see what happens8 ,it rattles away like a valve chattering1 because the steam rising from the boiling water sends the valve up and down1 and forces itself out1 and so makes it clatter4 ,you can very easily perceive that the flask is quite full of steam1 or else it would not force its way out4 ,you see1 also1 that the flask contains a substance very much larger than the water1 for it fills the whole of the flask over and over again1 and there it is blowing away into the air2 and yet you cannot observe any great diminution in the bulk of the water1 which shews you that its change of bulk is very great when it becomes steam4 ,i have put our iron bottles containing water into this freezing mixture1 that you may see what happens4 ,no communication will take place1 you observe1 between the water in the bottles and the ice in the outer vessel4 ,but there will be a conveyance of heat from the one to the other2 and if we are successful--we are making our experiment in very great haste--,i expect you will by-and-by1 so soon as the cold has taken possession of the bottles and their contents1 hear a pop on the occasion of the bursting of the one bottle or the other2 and1 when we come to examine the bottles1 we shall find their contents masses of ice1 partly enclosed by the covering of iron which is too small for them1 because the ice is larger in bulk than the water4 ,you know very well that ice floats upon water3 if a boy falls through a hole into the water1 he tries to get on the ice again to float him up4 ,why does the ice float8--think of that1 and philosophise4 ,because the ice is larger than the quantity of water which can produce it2 and therefore the ice weighs the lighter1 and the water is the heavier4 ,to return now to the action of heat on water4 ,see what a stream of vapour is issuing from this tin vessel6 ,you observe1 we must have made it quite full of steam to have it sent out in that great quantity4 ,and now1 as we can convert the water into steam by heat1 we convert it back into liquid water by the application of cold4 ,and if we take a glass1 or any other cold thing1 and hold it over this steam1 see how soon it gets damp with water2 it will condense it until the glass is warm--it condenses the water which is now running down the sides of it4 ,i have here another experiment to shew the condensation of water from a vaporous state back into a liquid state1 in the same way as the vapour1 one of the products of the candle1 was condensed against the bottom of the dish1 and obtained in the form of water2 and to shew you how truly and thoroughly these changes take place1 ,i will take this tin flask1 which is now full of steam1 and close the top4 ,we shall see what takes place when we cause this water or steam to return back to the fluid state by pouring some cold water on the outside4 ,the ,lecturer poured the cold water over the vessel1 when it immediately collapsed4 ,you see what has happened4 ,if ,i had closed the stopper1 and still kept the heat applied to it1 it would have burst the vessel2 yet1 when the steam returns to the state of water1 the vessel collapses1 there being a vacuum produced inside by the condensation of the steam4 ,i shew you these experiments for the purpose of pointing out that in all these occurrences there is nothing that changes the water into any other thing--it still remains water2 and so the vessel is obliged to give way1 and is crushed inwards1 as in the other case1 by the further application of heat1 it would have been blown outwards4 ,illustration3 ,fig4 #ab4 ,and what do you think the bulk of that water is when it assumes the vaporous condition8 ,you see that cube pointing to a cubic foot4 ,there1 by its side1 is a cubic inch1 exactly the same shape as the cubic foot1 and that bulk of water the cubic inch is sufficient to expand into that bulk the cubic foot of steam2 and1 on the contrary1 the application of cold will contract that large quantity of steam into this small quantity of water4 ,illustration3 ,fig4 #ac4 ,one of the iron bottles burst at that moment4 ,ah6 ,there is one of our bottles burst1 and here you see is a crack down one side an eighth of an inch in width4 ,the other now exploded1 sending the freezing mixture in all directions4 ,this other bottle is also broken2 although the iron was nearly half-an-inch thick1 the ice has burst it asunder4 ,these changes always take place in water3 they do not require to be always produced by artificial means1--we only use them here because we want to produce a small winter round that little bottle1 instead of a long and severe one4 ,but if you go to ,canada1 or to the ,north1 you will find the temperature there out of doors will do the same thing as has been done here by the freezing mixture4 ,to return to our quiet philosophy4 ,we shall not in future be deceived1 therefore1 by any changes that are produced in water4 ,water is the same everywhere1 whether produced from the ocean or from the flame of the candle4 ,where1 then1 is this water which we get from a candle8 ,i must anticipate a little1 and tell you4 ,it evidently comes1 as to part of it1 from the candle2 but is it within the candle beforehand8 ,no4 ,it is not in the candle2 and it is not in the air round about the candle which is necessary for its combustion4 ,it is neither in one nor the other1 but it comes from their conjoint action1 a part from the candle1 a part from the air2 and this we have now to trace1 so that we may understand thoroughly what is the chemical history of a candle when we have it burning on our table4 ,how shall we get at this8 ,i myself know plenty of ways1 but ,i want you to get at it from the association in your own minds of what ,i have already told you4 ,i think you can see a little in this way4 ,we had just now the case of a substance which acted upon the water in the way that ,sir ,humphrey ,davy shewed us#ac1 and which ,i am now going to recall to your minds by making again an experiment upon that dish4 ,it is a thing which we have to handle very carefully1 for you see1 if ,i allow a little splash of water to come upon this mass1 it sets fire to part of it2 and if there were free access of air1 it would quickly set fire to the whole4 ,now1 this is a metal--a beautiful and bright metal--which rapidly changes in the air1 and1 as you know1 rapidly changes in water4 ,i will put a piece on the water1 and you see it burns beautifully1 making a floating lamp1 using the water in the place of air4 ,again1 if we take a few iron filings or turnings1 and put them in water1 we find that they likewise undergo an alteration4 ,they do not change so much as this potassium does1 but they change somewhat in the same way2 they become rusty1 and shew an action upon the water1 though in a different degree of intensity to what this beautiful metal does3 but they act upon the water in the same manner generally as this potassium4 ,i want you to put these different facts together in your minds4 ,i have another metal here zinc1 and when we examined it with regard to the solid substance produced by its combustion1 we had an opportunity of seeing that it burned2 and ,i suppose1 if ,i take a little strip of this zinc and put it over the candle1 you will see something half-way1 as it were1 between the combustion of potassium on the water and the action of iron1--you see there is a sort of combustion4 ,it has burned1 leaving a white ash or residuum1 and here also we find that the metal has a certain amount of action upon water4 ,by degrees we have learned how to modify the action of these different substances1 and to make them tell us what we want to know4 ,and now1 first of all1 ,i take iron4 ,it is a common thing in all chemical reactions1 where we get any result of this kind1 to find that it is increased by the action of heat2 and if we want to examine minutely and carefully the action of bodies one upon another1 we often have to refer to the action of heat4 ,you are aware1 ,i believe1 that iron-filings burn beautifully in the air2 but ,i am about to shew you an experiment of this kind1 because it will impress upon you what ,i am going to say about iron in its action on water4 ,if ,i take a flame and make it hollow2--you know why1 because ,i want to get air to it and into it1 and therefore ,i make it hollow--and then take a few iron-filings and drop them into the flame1 you see how well they burn4 ,that combustion results from the chemical action which is going on when we ignite those particles4 ,and so we proceed to consider these different effects1 and ascertain what iron will do when it meets with water4 ,it will tell us the story so beautifully1 so gradually and regularly1 that ,i think it will please you very much4 ,i have here a furnace with a pipe going through it like an iron gun barrel1 and ,i have stuffed that barrel full of bright iron-turnings1 and placed it across the fire1 to be made red-hot4 ,we can either send air through the barrel to come in contact with the iron1 or we can send steam from this little boiler at the end of the barrel4 ,here is a stop-cock which shuts off the steam from the barrel until we wish to admit it4 ,there is some water in these glass jars1 which ,i have coloured blue1 so that you may see what happens4 ,now1 you know very well that any steam ,i might send through that barrel1 if it went through into the water1 would be condensed2 for you have seen that steam cannot retain its gaseous form if it be cooled down4 ,illustration3 ,fig4 #ad4 ,you saw it here pointing to the tin flask crushing itself into a small bulk1 and causing the flask holding it to collapse2 so that if ,i were to send steam through that barrel1 it would be condensed--supposing the barrel were cold3 it is1 therefore1 heated to perform the experiment ,i am now about to shew you4 ,i am going to send the steam through the barrel in small quantities2 and you shall judge for yourselves1 when you see it issue from the other end1 whether it still remains steam4 ,steam is condensable into water1 and when you lower the temperature of steam1 you convert it back into fluid water2 but ,i have lowered the temperature of the gas which ,i have collected in this jar1 by passing it through water after it has traversed the iron barrel1 and still it does not change back into water4 ,i will take another test and apply to this gas4 7,i hold the jar in an inverted position1 or my substance would escape47 ,if ,i now apply a light to the mouth of the jar1 it ignites with a slight noise4 ,that tells you that it is not steam4 ,steam puts out a fire--it does not burn2 but you saw that what ,i had in that jar burnt4 ,we may obtain this substance equally from water produced from the candle-flame as from any other source4 ,when it is obtained by the action of the iron upon the aqueous vapour1 it leaves the iron in a state very similar to that in which these filings were after they were burnt4 ,it makes the iron heavier than it was before4 ,so long as the iron remains in the tube and is heated1 and is cooled again without the access of air or water1 it does not change in its weight2 but after having had this current of steam passed over it1 it then comes out heavier that it was before1 having taken something out of the steam1 and having allowed something else to pass forth1 which we see here4 ,and now1 as we have another jar full1 ,i will shew you something most interesting4 ,it is a combustible gas2 and ,i might at once take this jar and set fire to the contents1 and shew you that it is combustible2 but ,i intend to shew you more if ,i can4 ,it is also a very light substance4 ,steam will condense3 this body will rise in the air1 and not condense4 ,illustration3 ,fig4 #ae ,suppose ,i take another glass jar1 empty of all but air3 if ,i examine it with a taper1 ,i shall find that it contains nothing but air4 ,i will now take this jar full of the gas that ,i am speaking of1 and deal with it as though it were a light body4 ,i will hold both upside-down1 and turn the one up under the other2 and that which did contain the gas procured from the steam1 what does it contain now8 ,you will find it now only contains air4 ,but look6 ,here is the combustible substance taking the other jar which ,i have poured out of the one jar into the other4 ,it still preserves its quality1 and condition1 and independence1 and therefore is the more worthy of our consideration1 as belonging to the products of a candle4 ,now1 this substance which we have just prepared by the action of iron on the steam or water1 we can also get by means of those other things which you have already seen act so well upon the water4 ,if ,i take a piece of potassium1 and make the necessary arrangements1 it will produce this gas2 and if1 instead1 a piece of zinc1 ,i find1 when ,i come to examine it very carefully1 that the main reason why this zinc cannot act upon the water continuously as the other metal does1 is because the result of the action of the water envelopes the zinc in a kind of protecting coat4 ,we have learned in consequence1 that if we put into our vessel only the zinc and water1 they by themselves do not give rise to much action1 and we get no result4 ,but suppose ,i proceed to dissolve off this varnish--this encumbering substance--which ,i can do by a little acid2 the moment ,i do this1 ,i find the zinc acting upon the water exactly as the iron did1 but at the common temperature4 ,the acid in no way is altered1 except in its combination with the oxide of zinc1 which is produced4 ,i have now poured the acid into the glass1 and the effect is as though ,i were applying heat to cause this boiling up4 ,there is something coming off from the zinc very abundantly1 which is not steam4 ,there is a jar full of it2 and you will find that ,i have exactly the same combustible substance remaining in the vessel1 when ,i hold it upside-down1 that ,i produced during the experiment with the iron barrel4 ,this is what we get from water--the same substance which is contained in the candle4 ,illustration3 ,fig4 #af4 ,let us now trace distinctly the connection between these two points4 ,this is hydrogen--a body classed among those things which in ,chemistry we call elements1 because we can get nothing else out of them4 ,a candle is not an elementary body1 because we can get carbon out of it2 we can get this hydrogen out of it1 or at least out of the water which it supplies4 ,and this gas has been so named hydrogen1 because it is that element which1 in association with another1 generates water4 ,footnote3 greek3 hudos1 8water10 and greek3 gennao1 8,i generate40 ,mr4 ,anderson having now been able to get two or three jars of gas1 we shall have a few experiments to make1 and ,i want to shew you the best way of making these experiments4 ,i am not afraid to shew you1 for ,i wish you to make experiments1 if you will only make them with care and attention1 and the assent of those around you4 ,as we advance in ,chemistry1 we are obliged to deal with substances which are rather injurious1 if in their wrong places--the acids1 and heat1 and combustible things we use1 might do harm if carelessly employed4 ,if you want to make hydrogen1 you can make it easily from bits of zinc1 and sulphuric or muriatic acid4 ,here is what in former times was called the 8philosopher's candle40 ,it is a little phial with a cork1 and a tube or pipe passing through it4 ,illustration3 ,fig4 #ag4 ,and ,i am now putting a few little pieces of zinc into it4 ,this little instrument ,i am going to apply to a useful purpose in our demonstrations--for ,i want to shew you that you can prepare hydrogen1 and make some experiments with it as you please at your own homes4 ,let me here tell you why ,i am so careful to fill this phial nearly1 and yet not quite full4 ,i do it because the evolved gas1 which1 as you have seen1 is very combustible1 is explosive to a considerable extent when mixed with air1 and might lead to harm1 if you were to apply a light to the end of that pipe before all the air had been swept out of the space above the water4 ,i am now about to pour in the sulphuric acid4 ,i have used very little zinc1 and more sulphuric acid and water1 because ,i want to keep it at work for some time4 ,i therefore take care in this way to modify the proportions of the ingredients1 so that ,i may have a regular supply--not too quick1 and not too slow4 ,supposing ,i now take a glass and put it upside-down over the end of the tube1 because the hydrogen is light ,i expect that it will remain in that vessel a little while4 ,we will now test the contents of our glass to see if there be hydrogen in it4 ,i think ,i am safe in saying we have caught some applying a light4 ,there it is1 you see4 ,i will now apply a light to the top of the tube4 ,there is the hydrogen burning4 ,there is our philosophical candle4 ,it is a foolish feeble sort of a flame1 you may say2 but it is so hot that scarcely any common flame gives out so much heat4 ,it goes on burning regularly1 and ,i am now about to put that flame to burn under a certain arrangement1 in order that we may examine its results and make use of the information which we may thereby acquire4 ,inasmuch as the candle produces water1 and this gas comes out of the water1 let us see what this gives us by the same process of combustion that the candle went through when it burnt in the atmosphere2 and for that purpose ,i am going to put the lamp under this apparatus1 in order to condense whatever may arise from the combustion within it ,in the course of a short time you will see moisture appearing in the cylinder1 and you will get the water running down the side2 and the water from this hydrogen flame will have absolutely the same effect upon all our tests1 being obtained by the same general process as in the former case4 ,this hydrogen is a very beautiful substance4 ,it is so light that it carries things up3 it is far lighter than the atmosphere2 and ,i dare say ,i can shew you this by an experiment which1 if you are very clever1 some of you may even have skill enough to repeat4 ,here is our generator of hydrogen1 and here are some soap-suds4 ,i have an india-rubber tube connected with the hydrogen generator1 and at the end of the tube is a tobacco-pipe4 ,illustration3 ,fig4 #ah4 ,i can thus put the pipe into the suds1 and blow bubbles by means of the hydrogen4 ,you observe how the bubbles fall downwards when ,i blow them with my warm breath2 but notice the difference when ,i blow them with hydrogen4 ,the ,lecturer here blew bubbles with hydrogen1 which rose to the roof of the theatre4 ,it shews you how light this gas must be in order to carry with it not merely the ordinary soap-bubble1 but the larger portion of a drop hanging to the bottom of it4 ,i can shew its lightness in a better way than this2 larger bubbles than these may be so lifted up2 indeed1 in former times balloons used to be filled with this gas4 ,mr4 ,anderson will fasten this tube on to our generator1 and we shall have a stream of hydrogen here with which we can charge this balloon made of collodion4 ,i need not even be very careful to get all the air out1 for ,i know the power of this gas to carry it up4 ,two collodion balloons were inflated1 and sent up1 one being held by a string4 ,here is another larger one made of thin membrane1 which we will fill and allow to ascend4 ,you will see they will all remain floating about until the gas escapes4 ,what1 then1 are the comparative weights of these substances8 ,i have a table here which will shew you the proportion which their weights bear to each other4 ,i have taken a pint and a cubic foot as the measures1 and have placed opposite to them the respective figures4 ,a pint measure of this hydrogen weighs three-quarters of our smallest weight 7a grain71 and a cubic foot weighs one-twelfth of an ounce2 whereas a pint of water weighs #h1gej grains1 and a cubic foot of water weighs almost #a1jjj ounces4 ,you see1 therefore1 what a vast difference there is between the weight of a cubic foot of water and a cubic foot of hydrogen4 ,hydrogen gives rise to no substance that can become solid1 either during combustion or afterwards as a product of its combustion4 ,but when it burns1 it produces water only2 and if we take a cold glass and put it over the flame1 it becomes damp1 and you have water1 produced immediately in appreciable quantity2 and nothing is produced by its combustion but the same water which you have seen the flame of the candle produce4 ,it is important to remember that this hydrogen is the only thing in nature which furnishes water as the sole product of combustion4 ,and now we must endeavour to find some additional proof of the general character and composition of water2 and for this purpose ,i will keep you a little longer1 so that at our next meeting we may be better prepared for the subject4 ,we have the power of arranging the zinc which you have seen acting upon the water by the assistance of an acid1 in such a manner as to cause all the power to be evolved in the place where we require it ,i have behind me a voltaic pile1 and ,i am just about to shew you1 at the end of this lecture1 its character and power1 that you may see what we shall have to deal with when next we meet4 ,i hold here the extremities of the wires which transport the power from behind me1 and which ,i shall cause to act on the water4 ,we have previously seen what a power of combustion is possessed by the potassium1 or the zinc1 or the iron-filings2 but none of them shew such energy as this4 ,the ,lecturer here made contact between the two terminal wires of the battery1 when a brilliant flash of light was produced4 ,this light is1 in fact1 produced by a forty-zinc power of burning3 it is a power that ,i can carry about in my hands1 through these wires1 at pleasure--although1 if ,i applied it wrongly to myself1 it would destroy me in an instant1 for it is a most intense thing1 and the power you see here put forth while you count five bringing the poles in contact1 and exhibiting the electric light is equivalent to the power of several thunder-storms1 so great is its force#ad4 ,and that you may see what intense energy it has1 ,i will take the ends of the wires which convey the power from the battery1 and with it ,i dare say ,i can burn this iron file4 ,now1 this is a chemical power1 and one which1 when we next meet1 ,i shall apply to water1 and shew you what results we are able to produce4 ,,lecture ,,iv4 ,,hydrogen ,,in ,,the ,,candle--,,burns ,,into ,,water--,,the ,,other ,,part ,,of ,,water--,,oxygen4 ,i see you are not tired of the candle yet1 or ,i am sure you would not be interested in the subject in the way you are4 ,when our candle was burning1 we found it produced water exactly like the water we have around us2 and by further examination of this water we found in it that curious body1 hydrogen--that light substance of which there is some in this jar4 ,we afterwards saw the burning powers of that hydrogen1 and that it produced water4 ,and ,i think ,i introduced to your notice an apparatus which ,i very briefly said was an arrangement of chemical force1 or power1 or energy1 so adjusted as to convey its power to us in these wires2 and ,i said ,i should use that force to pull the water to pieces1 to see what else there was in the water besides hydrogen2 because1 you remember1 when we passed the water through the iron tube1 we by no means got the weight of water back which we put in1 in the form of steam1 though we had a very large quantity of gas evolved4 ,we have now to see what is the other substance present4 ,that you may understand the character and use of this instrument1 let us make an experiment or two4 ,let us put together1 first of all1 some substances1 knowing what they are1 and then see what that instrument does to them4 ,there is some copper 7observe the various changes which it can undergo71 and here is some nitric acid1 and you will find that this1 being a strong chemical agent1 will act very powerfully when ,i add it to the copper4 ,it is now sending forth a beautiful red vapour2 but as we do not want that vapour1 ,mr4 ,anderson will hold it near the chimney for a short time1 that we may have the use and beauty of the experiment without the annoyance4 ,the copper which ,i have put into the flask will dissolve3 it will change the acid and the water into a blue fluid1 containing copper and other things2 and ,i propose then shewing you how this voltaic battery deals with it2 and in the mean time we will arrange another kind of experiment for you to see what power it has4 ,this is a substance which is to us like water--that is to say1 it contains bodies which we do not know of as yet1 as water contains a body which we do not know as yet4 ,now1 this solution of a salt#ae ,i will put upon paper1 and spread about1 and apply the power of the battery to it1 and observe what will happen4 ,three or four important things will happen which we shall take advantage of4 ,i place this wetted paper upon a sheet of tinfoil1 which is convenient for keeping all clean1 and also for the advantageous application of the power2 and this solution1 you see1 is not at all affected by being put upon the paper or tinfoil1 nor by anything else ,i have brought in contact with it yet1 and which1 therefore1 is free to us to use as regards that instrument4 ,but first let us see that our instrument is in order4 ,here are our wires4 ,let us see whether it is in the state in which it was last time4 ,we can soon tell4 ,as yet1 when ,i bring them together1 we have no power1 because the conveyers--what we call the electrodes--the passages or ways for the electricity--are stopped2 but now ,mr4 ,anderson by that referring to a sudden flash at the ends of the wires has given me a telegram to say that it is ready4 ,before ,i begin our experiment ,i will get ,mr4 ,anderson to break contact again at the battery behind me1 and we will put a platinum-wire across to connect the poles1 and then if ,i find ,i can ignite a pretty good length of this wire1 we shall be safe in our experiment4 ,now you will see the power4 ,the connection was established1 and the intermediate wire became red-hot4 ,there is the power running beautifully through the wire1 which ,i have made thin on purpose to shew you that we have those powerful forces2 and now1 having that power1 we will proceed with it to the examination of water4 ,i have here two pieces of platinum1 and if ,i lay them down upon this piece of paper the moistened paper on the tinfoil1 you will see no action2 and if ,i take them up1 there is no change that you can see1 but the arrangement remains just as it was before4 ,but1 now1 see what happens3 if ,i take these two poles and put either one or the other of them down separately on the platinum-plates1 they do nothing for me1 both are perfectly without action2 but if ,i let them both be in contact at the same moment1 see what happens a brown spot appeared under each pole of the battery4 ,look here at the effect that takes place1 and see how ,i have pulled something apart from the white--something brown2 and ,i have no doubt1 if ,i were to arrange it thus1 and were to put one of the poles to the tinfoil on the other side of the paper--why1 ,i get such a beautiful action upon the paper1 that ,i am going to see whether ,i cannot write with it--a telegram1 if you please4 ,the ,lecturer here traced the word 8juvenile0 on the paper with one of the terminal wires4 ,see there how beautifully we can get our results6 ,you see we have here drawn something1 which we have not known about before1 out of this solution4 ,let us now take that flask from ,mr4 ,andersen's hands1 and see what we can draw out of that4 ,this1 you know1 is a liquid which we have just made up from copper and nitric acid1 whilst our other experiments were in hand2 and though ,i am making this experiment very hastily1 and may bungle a little1 yet ,i prefer to let you see what ,i do rather than prepare it beforehand4 ,now1 see what happens4 ,these two platinum-plates are the two ends 7or ,i will make them so immediately7 of this apparatus2 and ,i am about to put them in contact with that solution just as we did a moment ago on the paper4 ,it does not matter to us whether the solution be on the paper or whether it be in the jar1 so long as we bring the ends of the apparatus to it4 ,if ,i put the two platinums in by themselves1 they come out as clean and as white as they go in inserting them into the fluid without connecting them with the battery2 but when we take the power and lay that on the platinums were connected with the battery and again dipped into the solution1 this1 you see exhibiting one of the platinums1 is at once turned into copper1 as it were3 it has become like a plate of copper2 and that exhibiting the other piece of platinum has come out quite clean4 ,if ,i take this coppered piece and change sides1 the copper will leave the right-hand side and come over to the left side2 what was before the coppered plate comes out clean1 and the plate which was clean comes out coated with copper2 and thus you see that the same copper we put into this solution we can also take out of it by means of this instrument4 ,putting that solution aside1 let us now see what effect this instrument will have upon water4 ,here are two little platinum-plates which ,i intend to make the ends of the battery1 and this 7,c7 is a little vessel so shaped as to enable me to take it to pieces1 and shew you its construction4 ,in these two cups 7,a and ,b7 ,i pour mercury1 which touches the ends of the wires connected with the platinum-plates4 ,in the vessel 7,c7 ,i pour some water containing a little acid 7but which is put only for the purpose of facilitating the action2 it undergoes no change in the process71 and connected with the top of the vessel is a bent glass tube 7,d71 which may remind you of the pipe which was connected with the gun barrel in our furnace experiment1 and which now passes under the jar 7,f74 ,i have now adjusted this apparatus1 and we will proceed to affect the water in some way or other4 ,in the other case1 ,i sent the water through a tube which was made red-hot2 ,i am now going to pass the electricity through the contents of this vessel4 ,perhaps ,i may boil the water2 if ,i do boil the water1 ,i shall get steam2 and you know that steam condenses when it gets cold1 and you will therefore see by that whether ,i do boil the water or not4 ,perhaps1 however1 ,i shall not boil the water1 but produce some other effect4 ,you shall have the experiment and see4 ,there is one wire which ,i will put to this side 7,a71 and here is the other wire which ,i will put to the other side 7,b71 and you will soon see whether any disturbance takes place4 ,here it is seeming to boil up famously2 but does it boil8 ,let us see whether that which goes out is steam or not4 ,i think you will soon see the jar 7,f7 will be filled with vapour1 if that which rises from the water is steam4 ,but can it be steam8 ,why1 certainly not2 because there it remains1 you see1 unchanged4 ,there it is standing over the water1 and it cannot therefore be steam1 but must be a permanent gas of some sort ,what is it8 ,is it hydrogen8 ,is it anything else8 ,well1 we will examine it4 ,if it is hydrogen1 it will burn4 ,the ,lecturer then ignited a portion of the gas collected1 which burnt with an explosion4 ,illustration3 ,fig4 #ai ,it is certainly something combustible1 but not combustible in the way that hydrogen is4 ,hydrogen would not have given you that noise2 but the colour of that light1 when the thing did burn1 was like that of hydrogen3 it will1 however1 burn without contact with the air4 ,that is why ,i have chosen this other form of apparatus1 for the purpose of pointing out to you what are the particular circumstances of this experiment4 ,in place of an open vessel ,i have taken one that is closed 7our battery is so beautifully active that we are even boiling the mercury1 and getting all things right--not wrong1 but vigorously right72 and ,i am going to shew you that that gas1 whatever it may be1 can burn without air1 and in that respect differs from a candle1 which cannot burn without the air4 ,and our manner of doing this is as follows3--,i have here a glass vessel 7,g7 which is fitted with two platinum-wires 7,,ik71 through which ,i can apply electricity2 and we can put the vessel on the air-pump and exhaust the air1 and when we have taken the air out we can bring it here and fasten it on to this jar 7,f71 and let into the vessel that gas which was formed by the action of the voltaic battery upon the water1 and which we have produced by changing the water into it1--for ,i may go as far as this1 and say we have really1 by that experiment1 changed the water into that gas4 ,we have not only altered its condition1 but we have changed it really and truly into that gaseous substance1 and all the water is there which was decomposed by the experiment4 ,as ,i screw this vessel 7,,gh7 on here 7,h71 and make the tubes well connected1 and when ,i open the stop-cocks 7,,hhh71 if you watch the level of the water 7in ,f71 you will see that the gas will rise4 ,i will now close the stop-cocks1 as ,i have drawn up as much as the vessel can hold1 and being safely conveyed into that chamber1 ,i will pass into it an electric spark from this ,leyden jar 7,l71 when the vessel1 which is now quite clear and bright1 will become dim4 ,there will be no sound1 for the vessel is strong enough to confine the explosion4 ,a spark was then passed through the jar1 when the explosive mixture was ignited4 ,did you see that brilliant light8 ,if ,i again screw the vessel on to the jar1 and open these stop-cocks1 you will see that the gas will rise a second time4 ,the stop-cocks were then opened4 ,those gases referring to the gases first collected in the jar1 and which had just been ignited by the electric spark have disappeared1 as you see3 their place is vacant1 and fresh gas has gone in4 ,water has been formed from them2 and if we repeat our operation repeating the last experiment1 ,i shall have another vacancy1 as you will see by the water rising4 ,i always have an empty vessel after the explosion1 because the vapour or gas into which that water has been resolved by the battery explodes under the influence of the spark1 and changes into water2 and by-and-by you will see in this upper vessel some drops of water trickling down the sides and collecting at the bottom4 ,we are here dealing with water entirely1 without reference to the atmosphere4 ,the water of the candle had the atmosphere helping to produce it2 but in this way it can be produced independently of the air4 ,water1 therefore1 ought to contain that other substance which the candle takes from the air1 and which1 combining with the hydrogen1 produces water4 ,just now you saw that one end of this battery took hold of the copper1 extracting it from the vessel which contained the blue solution4 ,it was effected by this wire2 and surely we may say1 if the battery has such power with a metallic solution which we made and unmade1 may we not find that it is possible to split asunder the component parts of the water1 and put them into this place and that place8 ,suppose ,i take the poles--the metallic ends of this battery--and see what will happen with the water in this apparatus 7fig4 #bj71 where we have separated the two ends far apart4 ,illustration3 ,fig4 #bj4 ,i place one here 7at ,a71 and the other there 7at ,b71 and ,i have little shelves with holes which ,i can put upon each pole1 and so arrange them that whatever escapes from the two ends of the battery will appear as separate gases2 for you saw that the water did not become vaporous1 but gaseous4 ,the wires are now in perfect and proper connection with the vessel containing the water2 and you see the bubbles rising3 let us collect these bubbles and see what they are4 ,here is a glass cylinder 7,o72 ,i fill it with water and put it over one end 7,a7 of the pile2 and ,i will take another 7,h7 and put it over the other end 7,b7 of the pile4 ,and so now we have a double apparatus1 with both places delivering gas4 ,both these jars will fill with gas4 ,there they go1 that to the right 7,h7 filling very rapidly2 the one to the left 7,o7 filling not so rapidly2 and though ,i have allowed some bubbles to escape1 yet still the action is going on pretty regularly2 and were it not that one is rather smaller than the other1 you would see that ,i should have twice as much in this 7,h7 as ,i have in that 7,o74 ,both these gases are colourless2 they stand over the water without condensing2 they are alike in all things--,i mean in all apparent things2 and we have here an opportunity of examining these bodies and ascertaining what they are4 ,their bulk is large1 and we can easily apply experiments to them4 ,i will take this jar 7,h7 first1 and will ask you to be prepared to recognise hydrogen4 ,think of all its qualities--the light gas which stood well in inverted vessels1 burning with a pale flame at the mouth of the jar--and see whether this gas does not satisfy all these conditions4 ,if it be hydrogen1 it will remain here while ,i hold this jar inverted4 ,a light was then applied1 when the hydrogen burnt ,what is there now in the other jar8 ,you know that the two together made an explosive mixture4 ,but what can this be which we find as the other constituent in water1 and which must therefore be that substance which made the hydrogen burn8 ,we know that the water we put into the vessel consisted of the two things together4 ,we find one of these is hydrogen3 what must that other be which was in the water before the experiment1 and which we now have by itself8 ,i am about to put this lighted splinter of wood into the gas4 ,the gas itself will not burn1 but it will make the splinter of wood burn4 ,the ,lecturer ignited the end of the wood1 and introduced it into the jar of gas4 ,see how it invigorates the combustion of the wood1 and how it makes it burn far better than the air would make it burn2 and now you see by itself that every other substance which is contained in the water1 and which1 when the water was formed by the burning of the candle1 must have been taken from the atmosphere4 ,what shall we call it1 ,a1 ,b1 or ,c8 ,let us call it ,o--call it 8,oxygen30 it is a very good distinct-sounding name4 ,this1 then1 is the oxygen which was present in the water1 forming so large a part of it4 ,we shall now begin to understand more clearly our experiments and researches2 because1 when we have examined these things once or twice1 we shall soon see why a candle burns in the air4 ,when we have in this way analysed the water--that is to say1 separated1 or electrolysed its parts out of it--we get two volumes of hydrogen1 and one of the body that burns it4 ,and these two are represented to us on the following diagram1 with their weights also stated2 and we shall find that the oxygen is a very heavy body by comparison with the hydrogen4 ,it is the other element in water4 ,i had better1 perhaps1 tell you now how we get this oxygen abundantly1 having shewn you how we can separate it from the water4 ,oxygen1 as you will immediately imagine1 exists in the atmosphere2 for how should the candle burn to produce water without it8 #a #h ,oxygen4 ,oxygen1 4 4 4 4 #hh4i ,hydrogen1 4 4 4 #aa4a ,hydrogen4 ---------- #i ,water14 4 4 4 4 #ajj4j ,such a thing would be absolutely impossible1 and chemically impossible1 without oxygen4 ,illustration3 ,fig4 #ba4 ,can we get it from the air8 ,well1 there are some very complicated and difficult processes by which we can get it from the air2 but we have better processes4 ,there is a substance called the black oxide of manganese3 it is a very black-looking mineral1 but very useful1 and when made red-hot it gives out oxygen4 ,here is an iron bottle which has had some of this substance put into it1 and there is a tube fixed to it1 and a fire ready made1 and ,mr4 ,anderson will put that retort into the fire1 for it is made of iron1 and can stand the heat4 ,here is a salt called chlorate of potassa1 which is now made in large quantities for bleaching1 and chemical and medical uses1 and for pyrotechnic and other purposes4 ,i will take some and mix it with some of the oxide of manganese 7oxide of copper1 or oxide of iron would do as well72 and if ,i put these together in a retort1 far less than a red heat is sufficient to evolve this oxygen from the mixture4 ,i am not preparing to make much1 because we only want sufficient for our experiments2 only1 as you will see immediately1 if ,i use too small a charge1 the first portion of the gas will be mixed with the air already in the retort1 and ,i should be obliged to sacrifice the first portion of the gas1 because it would be so much diluted with air2 the first portion must therefore be thrown away4 ,you will find in this case1 that a common spirit-lamp is quite sufficient for me to get the oxygen1 and so we shall have two processes going on for its preparation4 ,see how freely the gas is coming over from that small portion of the mixture4 ,we will examine it1 and see what are its properties4 ,now1 in this way we are producing1 as you will observe1 a gas just like the one we had in the experiment with the battery1 transparent1 undissolved by water1 and presenting the ordinary visible properties of the atmosphere4 7,as this first jar contains the air1 together with the first portions of the oxygen set free during the preparation1 we will carry it out of the way1 and be prepared to make our experiments in a regular1 dignified manner47 ,and1 inasmuch as that power of making wood1 wax1 or other things burn1 was so marked in the oxygen we obtained by means of the voltaic battery from water1 we may expect to find the same property here4 ,we will try it ,you see there is the combustion of a lighted taper in air1 and here is its combustion in this gas lowering the taper into the jar4 ,see how brightly and how beautifully it burns6 ,you can also see more than this1--you will perceive it is a heavy gas1 whilst the hydrogen would go up like a balloon1 or even faster than a balloon1 when not encumbered with the weight of the envelope4 ,illustration3 ,fig4 #bb4 ,you may easily see that although we obtained from water twice as much in volume of the hydrogen as of oxygen1 it does not follow that we have twice as much in weight--because one is heavy1 and the other a very light gas4 ,we have means of weighing gases or air2 but without stopping to explain1 that1 let me just tell you what their respective weights are4 ,the weight of a pint of hydrogen is three-quarters of a grain2 the weight of the same quantity of oxygen is nearly twelve grains4 ,this is a very great difference4 ,the weight of a cubit foot of hydrogen is one-twelfth of an ounce2 and the weight of a cubit foot of oxygen is one ounce and a third4 ,and so on we might come to masses of matter which may be weighed in the balance1 and which we can take account of as to hundredweights and as to tons1 as you will see almost immediately4 ,now1 as regards this very property of oxygen supporting combustion1 which we may compare to air1 ,i will take a piece of candle to shew it you in a rough way1 and the result will be rough4 ,there is our candle burning in the air3 how will it burn in oxygen8 ,i have here a jar of this gas1 and ,i am about to put it over the candle for you to compare the action of this gas with that of the air4 ,why1 look at it3 it looks something like the light you saw at the poles of the voltaic battery4 ,think how vigorous that action must be6 ,and yet1 during all that action1 nothing more is produced than what is produced by the burning of the candle in air4 ,we have the same production of water1 and the same phenomena exactly1 when we use this gas instead of air1 as we have when the candle is burnt in air4 ,but now we have got a knowledge of this new substance1 we can look at it a little more distinctly1 in order to satisfy ourselves that we have got a good general understanding of this part of the product of a candle4 ,it is wonderful how great the supporting powers of this substance are as regards combustion4 ,for instance1 here is a lamp which1 simple though it be1 is the original1 ,i may say1 of a great variety of lamps which are constructed for divers purposes--for light-houses1 microscopic illuminations1 and other uses2 and if it were proposed to make it burn very brightly1 you would say1 8,if a candle burnt better in oxygen1 will not a lamp do the same80 ,why1 it will do so4 ,mr4 ,anderson will give me a tube coming from our oxygen reservoir1 and ,i am about to apply it to this flame1 which ,i will previously make burn badly on purpose4 ,there comes the oxygen3 what a combustion that makes6 ,but if ,i shut it off1 what becomes of the lamp8 ,the flow of oxygen was stopped1 and the lamp relapsed to its former dimness4 ,it is wonderful how1 by means of oxygen1 we get combustion accelerated4 ,but it does not affect merely the combustion of hydrogen1 or carbon1 or the candle2 but it exalts all combustions of the common kind4 ,we will take one which relates to iron1 for instance1 as you have already seen iron burn a little in the atmosphere4 ,here is a jar of oxygen1 and this is a piece of iron wire2 but if it were a bar as thick as my wrist1 it would burn the same4 ,illustration3 ,fig4 #bc4 ,i first attach a little piece of wood to the iron1 ,i then set the wood on fire and let them both down together into the jar4 ,the wood is now alight1 and there it burns as wood should burn in oxygen2 but it will soon communicate its combustion to the iron4 ,the iron is now burning brilliantly1 and will continue so for a long time4 ,as long as we supply oxygen1 so long can we carry on the combustion of the iron1 until the latter is consumed4 ,we will now put that on one side1 and take some other substance2 but we must limit our experiments1 for we have not time to spare for all the illustrations you would have a right to if we had more time4 ,we will take a piece of sulphur--you know how sulphur burns in the air--well1 we put it into the oxygen1 and you will see that whatever can burn in air1 can burn with a far greater intensity in oxygen1 leading you to think that perhaps the atmosphere itself owes all its power of combustion to this gas4 ,the sulphur is now burning very quietly in the oxygen2 but you cannot for a moment mistake the very high and increased action which takes place when it is so burnt1 instead of being burnt merely in common air4 ,illustration3 ,fig4 #bd4 ,i am now about to shew you the combustion of another substance--phosphorus4 ,i can do it better for you here than you can do it at home4 ,this is a very combustible substance2 and if it be so combustible in air1 what might you expect it would be in oxygen8 ,i am about to shew it to you not in its fullest intensity1 for if ,i did so we should almost blow the apparatus up--,i may even now crack the jar1 though ,i do not want to break things carelessly4 ,you see how it burns in the air4 ,but what a glorious light it gives out when ,i introduce it into oxygen6 ,introducing the lighted phosphorus into the jar of oxygen4 ,there you see the solid particles going off which cause that combustion to be so brilliantly luminous4 ,thus far we have tested this power of oxygen1 and the high combustion it produces by means of other substances4 ,we must now1 for a little while longer1 look at it as respects the hydrogen4 ,you know1 when we allowed the oxygen and the hydrogen derived from the water to mix and burn together1 we had a little explosion4 ,you remember1 also1 that when ,i burnt the oxygen and the hydrogen in a jet together1 we got very little light1 but great heat4 ,i am now about to set fire to oxygen and hydrogen1 mixed in the proportion in which they occur in water4 ,here is a vessel containing one volume of oxygen and two volumes of hydrogen4 ,this mixture is exactly of the same nature as the gas we just now obtained from the voltaic battery3 it would be far too much to burn at once2 ,i have therefore arranged to blow soap-bubbles with it1 and burn those bubbles1 that we may see by a general experiment or two how this oxygen supports the combustion of the hydrogen4 ,first of all1 we will see whether we can blow a bubble4 ,well1 there goes the gas causing it to issue through a tobacco-pipe into some soap-suds4 ,here ,i have a bubble4 ,i am receiving them on my hand3 and you will perhaps think ,i am acting oddly in this experiment2 but it is to shew you that we must not always trust to noise and sounds1 but rather to real facts4 ,exploding a bubble on the palm of his hand4 ,i am afraid to fire a bubble from the end of the pipe1 because the explosion would pass up into the jar and blow it to pieces4 ,this oxygen then will unite with the hydrogen1 as you see by the phenomena1 and hear by the sound1 with the utmost readiness of action1 and all its powers are then taken up in its neutralisation of the qualities of the hydrogen4 ,so now ,i think you will perceive the whole history of water with reference to oxygen and the air1 from what we have before said4 ,why does a piece of potassium decompose water8 ,because it finds oxygen in the water4 ,what is set free when ,i put it in the water1 as ,i am about to do again8 ,it sets free hydrogen1 and the hydrogen burns2 but the potassium itself combines with oxygen2 and this piece of potassium1 in taking the water apart--the water1 you may say1 derived from the combustion of the candle--takes away the oxygen which the candle took from the air1 and so sets the hydrogen free2 and even if ,i take a piece of ice1 and put a piece of potassium upon it1 the beautiful affinities by which the oxygen and the hydrogen are related are such1 that the ice will absolutely set fire to the potassium4 ,i shew this to you to-day1 in order to enlarge your ideas of these things1 and that you may see how greatly results are modified by circumstances4 ,there is the potassium on the ice1 producing a sort of volcanic action4 ,it will be my place1 when next we meet1 having pointed out these anomalous actions1 to shew you that none of these extra and strange effects are met with by us--that none of these strange and injurious actions take place when we are burning1 not merely a candle1 but gas in our streets1 or fuel in our fireplaces1 so long as we confine ourselves within the laws that ,nature has made for our guidance4 ,,lecture ,v4 ,,oxygen ,,present ,,in ,,the ,,air--,,nature ,,of ,,the ,,atmosphere--,,its ,,properties--,,other ,,products ,,from ,,the ,,candle--,,carbonic ,,acid--,,its ,,properties4 ,we have now seen that we can produce hydrogen and oxygen from the water that we obtained from the candle4 ,hydrogen1 you know1 comes from the candle1 and oxygen1 you believe1 comes from the air4 ,but then you have a right to ask me1 8,how is it that the air and the oxygen do not equally well burn the candle80 ,if you remember what happened when ,i put a jar of oxygen over a piece of candle1 you recollect there was a very different kind of combustion to that which took place in the air4 ,now1 why is this8 ,it is a very important question1 and one ,i shall endeavour to make you understand3 it relates most intimately to the nature of the atmosphere1 and is most important to us4 ,we have several tests for oxygen besides the mere burning of bodies4 ,you have seen a candle burnt in oxygen1 or in the air2 you have seen phosphorus burnt in the air1 or in oxygen2 and you have seen iron-filings burnt in oxygen4 ,but we have other tests besides these1 and ,i am about to refer to one or two of them for the purpose of carrying your conviction and your experience further4 ,here we have a vessel of oxygen4 ,i will shew its presence to you3 if ,i take a little spark and put it into that oxygen1 you know1 by the experience you gained the last time we met1 what will happen2 if ,i put that spark into the jar1 it will tell you whether we have oxygen here or not4 ,yes6 ,we have proved it by combustion2 and now here is another test for oxygen1 which is a very curious and useful one4 ,i have here two jars full of gas1 with a plate between them to prevent their mixing2 ,i take the plate away1 and the gases are creeping one into the other4 8,what happens80 say you3 8they together produce no such combustion as was seen in the case of the candle40 ,but see how the presence of oxygen is told by its association with this other substance#ad4 ,what a beautifully coloured gas ,i have obtained in this way1 shewing me the presence of the oxygen6 ,in the same way we can try this experiment by mixing common air with this test-gas4 ,here is a jar containing air--such air as the candle would burn in--and here is a jar or bottle containing the test-gas4 ,i let them come together over water1 and you see the result3 the contents of the test-bottle are flowing into the jar of air1 and you see ,i obtain exactly the same kind of action as before1 and that shews me that there is oxygen in the air--the very same substance that has been already obtained by us from the water produced by the candle4 ,but then1 beyond that1 how is it that the candle does not burn in air as well as in oxygen8 ,we will come to that point at once4 ,i have here two jars2 they are filled to the same height with gas1 and the appearance to the eye is alike in both1 and ,i really do not know at present which of these jars contains oxygen and which contains air1 although ,i know they have previously been filled with these gases4 ,but here is our test-gas1 and ,i am going to work with the two jars1 in order to examine whether there is any difference between them in the quality of reddening this gas4 ,i am now going to turn this test-gas into one of the jars1 and observe what happens4 ,there is reddening1 you see2 there is then oxygen present4 ,we will now test the other jar2 but you see this is not so distinctly red as the first3 and1 further1 this curious thing happens1--if ,i take these two gases and shake them well together with water1 we shall absorb the red gas2 and then1 if ,i put in more of this test-gas and shake again1 we shall absorb more2 and ,i can go on as long as there be any oxygen present to produce that effect4 ,if ,i let in air1 it will not matter2 but the moment ,i introduce water1 the red gas disappears2 and ,i may go on in this way1 putting in more and more of the test-gas1 until ,i come to something left behind which will not redden any longer by the use of that particular body that rendered the air and the oxygen red4 ,why is that8 ,you see in a moment it is because there is1 besides oxygen1 something else present which is left behind4 ,i will let a little more air into the jar1 and if it turns red you will know that some of that reddening gas is still present1 and that consequently it was not for the want of this producing body that that air was left behind4 ,now1 you will begin to understand what ,i am about to say4 ,you saw that when ,i burnt phosphorus in a jar1 as the smoke produced by the phosphorus and the oxygen of the air condensed1 it left a good deal of gas unburnt1 just as this red gas left something untouched1--there was1 in fact1 this gas left behind1 which the phosphorus cannot touch1 which the reddening gas cannot touch1 and this something is not oxygen1 and yet is part of the atmosphere4 ,so that is one way of opening out air into the two things of which it is composed--oxygen1 which burns our candles1 our phosphorus1 or anything else2 and this other substance--nitrogen--which will not burn them4 ,this other part of the air is by far the larger proportion1 and it is a very curious body1 when we come to examine it2 it is remarkably curious1 and yet you say1 perhaps1 that it is very uninteresting4 ,it is uninteresting in some respects because of this--that it shews no brilliant effects of combustion4 ,if ,i test it with a taper as ,i do oxygen and hydrogen1 it does not burn like hydrogen1 nor does it make the taper burn like oxygen4 ,try it in any way ,i will1 it does neither the one thing nor the other3 it will not take fire2 it will not let the taper burn2 it puts out the combustion of everything4 ,there is nothing that will burn in it in common circumstances4 ,it has no smell2 it is not sour2 it does not dissolve in water2 it is neither an acid nor an alkali2 it is as indifferent to all our organs as it is possible for a thing to be4 ,and you might say1 8,it is nothing2 it is not worth chemical attention2 what does it do in the air80 ,ah6 then come our beautiful and fine results shewn us by an observant philosophy4 ,suppose1 in place of having nitrogen1 or nitrogen and oxygen1 we had pure oxygen as our atmosphere2 what would become of us8 ,you know very well that a piece of iron lit in a jar of oxygen goes on burning to the end4 ,when you see a fire in an iron grate1 imagine where the grate would go to if the whole of the atmosphere were oxygen4 ,the grate would burn up more powerfully than the coals--for the iron of the grate itself is even more combustible than the coals which we burn in it4 ,a fire put into the middle of a locomotive would be a fire in a magazine of fuel1 if the atmosphere were oxygen4 ,the nitrogen lowers it down and makes it moderate and useful for us1 and then1 with all that1 it takes away with it the fumes that you have seen produced from the candle1 disperses them throughout the whole of the atmosphere1 and carries them away to places where they are wanted to perform a great and glorious purpose of good to man1 for the sustenance of vegetation2 and thus does a most wonderful work1 although you say1 on examining it1 8,why1 it is a perfectly indifferent thing40 ,this nitrogen in its ordinary state is an inactive element2 no action short of the most intense electric force1 and then in the most infinitely small degree1 can cause the nitrogen to combine directly with the other element of the atmosphere1 or with other things round about it2 it is a perfectly indifferent1 and therefore to say1 a safe substance4 ,but before ,i take you to that result1 ,i must tell you about the atmosphere itself4 ,i have written on this diagram the composition of one hundred parts of atmospheric air3-- ,bulk4 ,weight4 ,oxygen1 4 4 4 4 4 #bj #bb4c ,nitrogen1 4 4 4 4 #hj #gg4g ------ ---------- #ajj #ajj4j ,it is a true analysis of the atmosphere1 so far as regards the quantity of oxygen and the quantity of nitrogen present4 ,by our analysis1 we find that #e pints of the atmosphere contain only #a pint of oxygen1 and #d pints1 or #d parts1 of nitrogen by bulk4 ,that is our analysis of the atmosphere4 ,it requires all that quantity of nitrogen to reduce the oxygen down1 so as to be able to supply the candle properly with fuel1 so as to supply us with an atmosphere which our lungs can healthily and safely breathe2 for it is just as important to make the oxygen right for us to breathe1 as it is to make the atmosphere right for the burning of the fire and the candle4 ,but now for this atmosphere4 ,first of all1 let me tell you the weight of these gases4 ,a pint of nitrogen weighs #aj grains1 or a cubic foot weighs #a ounce4 ,that is the weight of the nitrogen4 ,the oxygen is heavier3 a pint of it weighs #aa grains1 and a cubic foot weighs #a ounce4 ,a pint of air weighs about #aj grains1 and a cubic foot #a ounce4 ,illustration3 ,fig4 #be4 ,you have asked me several times1 and ,i am very glad you have1 8,how do you weigh gases80 ,i will shew you2 it is very simple1 and easily done4 ,here is a balance1 and here a copper bottle1 made as light as we can consistent with due strength1 turned very nicely in the lathe1 and made perfectly air-tight1 with a stop-cock1 which we can open and shut1 which at present is open1 and therefore allows the bottle to be full of air4 ,i have here a nicely-adjusted balance1 in which ,i think the bottle1 in its present condition1 will be balanced by the weight on the other side4 ,and here is a pump by which we can force the air into this bottle1 and with it we will force in a certain number of volumes of air1 as measured by the pump4 ,twenty measures were pumped in4 ,we will shut that in and put it in the balance4 ,see how it sinks3 it is much heavier than it was4 ,by what8 ,by the air that we have forced into it by the pump4 ,there is not a greater bulk of air1 but there is the same bulk of heavier air1 because we have forced in air upon it4 ,and that you may have a fair notion in your mind as to how much this air measures1 here is a jar full of water4 ,we will open that copper vessel into this jar1 and let the air return to its former state4 ,all ,i have to do now is to screw them tightly together1 and to turn the taps1 when there1 you see1 is the bulk of the twenty pumps of air which ,i forced into the bottle2 and to make sure that we have been quite correct in what we have been doing1 we will take the bottle again to the balance1 and1 if it is now counterpoised by the original weight1 we shall be quite sure we have made our experiment correctly4 ,illustration3 ,fig4 #bf4 ,it is balanced2 so1 you see1 we can find out the weight of the extra volumes of air forced in1 in that way1 and by that means we are able to ascertain that a cubic foot of air weighs #a ounce4 ,but that small experiment will by no means convey to your mind the whole literal truth of this matter4 ,it is wonderful how it accumulates when you come to larger volumes4 ,this bulk of air a cubic foot weighs #a ounce4 ,what do you think of the contents of that box above there1 which ,i have had made for the purpose8 ,the air which is within that box weighs one pound--a full pound2 and ,i have calculated the weight of the air in this room1--you would hardly imagine it1 but it is above a ton4 ,so rapidly do the weights rise up1 and so important is the presence of the atmosphere1 and of the oxygen and the nitrogen in it1 and the use it performs in conveying things to and fro from place to place1 and carrying bad vapours to places where they will do good instead of harm4 ,having given you that little illustration with respect to the weight of the air1 let me shew you certain consequences of it4 ,you have a right to them1 because you would not understand so much without it4 ,do you remember this kind of experiment8 ,have you ever seen it8 ,suppose ,i take a pump somewhat similar to the one ,i had a little while ago to force air into the bottle1 and suppose ,i place it in such a manner that by certain arrangements ,i can apply my hand to it3 my hand moves about in the air so easily that it seems to feel nothing1 and ,i can hardly get velocity enough by any motion of my own in the atmosphere to make sure that there is much resistance to it4 ,illustration3 ,fig4 #bg4 ,but1 when ,i put my hand here on the air-pump receiver1 which was afterwards exhausted1 you see what happens4 ,why is my hand fastened to this place1 and why am ,i able to pull this pump about8 ,and see6 how is it that ,i can hardly get my hand away8 ,why is this8 ,it is the weight of the air--the weight of the air that is above4 ,i have another experiment here1 which ,i think will explain to you more about it4 ,when the air is pumped from underneath the bladder which is stretched over this glass1 you will see the effect in another shape3 the top is quite flat at present1 but ,i will make a very little motion with the pump1 and now look at it--see how it has gone down1 see how it is bent in4 ,you will see the bladder go in more and more1 until at last ,i expect it will be driven in and broken by the force of the atmosphere pressing upon it4 ,illustration3 ,fig4 #bh4 ,the bladder at last broke with a loud report4 ,now1 that was done entirely by the weight of the air pressing on it1 and you can easily understand how that is4 ,the particles that are piled up in the atmosphere stand upon each other1 as these five cubes do4 ,you can easily conceive that four of these five cubes are resting upon the bottom one1 and if ,i take that away1 the others will all sink down4 ,so it is with the atmosphere3 the air that is above is sustained by the air that is beneath2 and when the air is pumped away from beneath them1 the change occurs which you saw when ,i placed my hand on the air-pump1 and which you saw in the case of the bladder1 and which you shall see better here4 ,i have tied over this jar a piece of sheet india-rubber1 and ,i am now about to take away the air from the inside of the jar2 and if you will watch the india-rubber--which acts as a partition between the air below and the air above--you will see1 when ,i pump1 how the pressure shews itself4 ,see where it is going to--,i can actually put my hand into the jar2 and yet this result is only caused by the great and powerful action of the air above4 ,how beautifully it shews this curious circumstance6 ,here is something that you can have a pull at1 when ,i have finished to-day4 ,it is a little apparatus of two hollow brass hemispheres1 closely fitted together1 and having connected with it a pipe and a cock1 through which we can exhaust the air from the inside2 and although the two halves are so easily taken apart1 while the air is left within1 yet you will see1 when we exhaust it by-and-by1 no power of any two of you will be able to pull them apart4 ,every square inch of surface that is contained in the area of that vessel sustains fifteen pounds by weight1 or nearly so1 when the air is taken out2 and you may try your strength presently in seeing whether you can overcome that pressure of the atmosphere4 ,here is another very pretty thing--the boys' sucker1 only refined by the philosopher4 ,we young ones have a perfect right to take toys1 and make them into philosophy1 inasmuch as now-a-days we are turning philosophy into toys4 ,here is a sucker1 only it is made of india-rubber3 if ,i clap it upon the table1 you see at once it holds4 ,why does it hold8 ,i can slip it about1 and yet if ,i try to pull it up1 it seems as if it would pull the table with it ,i can easily make it slip about from place to place2 but only when ,i bring it to the edge of the table can ,i get it off4 ,it is only kept down by the pressure of the atmosphere above4 ,we have a couple of them2 and if you take these two and press them together1 you will see how firmly they stick4 ,and1 indeed1 we may use them as they are proposed to be used1 to stick against windows1 or against walls1 where they will adhere for an evening1 and serve to hang anything on that you want4 ,i think1 however1 that you boys ought to be shewn experiments that you can make at home2 and so here is a very pretty experiment in illustration of the pressure of the atmosphere4 ,here is a tumbler of water4 ,suppose ,i were to ask you to turn that tumbler upside-down1 so that the water should not fall out1 and yet not be kept in by your hand1 but merely by using the pressure of the atmosphere4 ,could you do that8 ,take a wine-glass1 either quite full or half-full of water1 and put a flat card on the top1 turn it upside-down1 and then see what becomes of the card and of the water4 ,the air cannot get in because the water by its capillary attraction round the edge keeps it out4 ,i think this will give you a correct notion of what you may call the materiality of the air2 and when ,i tell you that the box holds a pound of it1 and this room more than a ton1 you will begin to think that air is something very serious4 ,i will make another experiment1 to convince you of this positive resistance4 ,there is that beautiful experiment of the popgun1 made so well and so easily1 you know1 out of a quill1 or a tube1 or anything of that kind1--where we take a slice of potato1 for instance1 or an apple1 and take the tube and cut out a pellet1 as ,i have now done1 and push it to one end4 ,i have made that end tight2 and now ,i take another piece and put it in3 it will confine the air that is within the tube perfectly and completely for our purpose2 and ,i shall now find it absolutely impossible by any force of mine to drive that little pellet close up to the other4 ,it cannot be done4 ,i may press the air to a certain extent1 but if ,i go on pressing1 long before it comes to the second1 the confined air will drive the front one out with a force something like that of gunpowder2 for gunpowder is in part dependent upon the same action that you see here exemplified4 ,i saw the other day an experiment which pleased me much1 as ,i thought it would serve our purpose here4 7,i ought to have held my tongue for four or five minutes before beginning this experiment1 because it depends upon my lungs for success47 ,by the proper application of air ,i expect to be able to drive this egg out of one cup into the other by the force of my breath2 but if ,i fail1 it is in a good cause2 and ,i do not promise success1 because ,i have been talking more than ,i ought to do to make the experiment succeed4 ,the ,lecturer here tried the experiment1 and succeeded in blowing the egg from one egg-cup to the other4 ,you see that the air which ,i blow goes downwards between the egg and the cup1 and makes a blast under the egg1 and is thus able to lift a heavy thing--for a full egg is a very heavy thing for air to lift4 ,if you want to make the experiment1 you had better boil the egg quite hard first1 and then you may very safely try to blow it from one cup to the other1 with a little care4 ,i have now kept you long enough upon this property of the weight of the air1 but there is another thing ,i should like to mention4 ,you saw the way in which1 in this popgun1 ,i was able to drive the second piece of potato half or two-thirds of an inch before the first piece started1 by virtue of the elasticity of the air--just as ,i pressed into the copper bottle the particles of air by means of the pump4 ,now1 this depends upon a wonderful property in the air1 namely1 its elasticity2 and ,i should like to give you a good illustration of this4 ,if ,i take anything that confines the air properly1 as this membrane1 which also is able to contract and expand so as to give us a measure of the elasticity of the air1 and confine in this bladder a certain portion of air2 and then1 if we take the atmosphere off from the outside of it1 just as in these cases we put the pressure on--if we take the pressure off1 you will see how it will then go on expanding and expanding1 larger and larger1 until it will fill the whole of this bell-jar1 shewing you that wonderful property of the air1 its elasticity1 its compressibility1 and expansibility1 to an exceedingly large extent1 and which is very essential for the purposes and services it performs in the economy of creation4 ,we will now turn to another very important part of our subject1 remembering that we have examined the candle in its burning1 and have found that it gives rise to various products4 ,we have the products1 you know1 of soot1 of water1 and of something else which you have not yet examined4 ,we have collected the water1 but have allowed the other things to go into the air4 ,let us now examine some of these other products4 ,here is an experiment which ,i think will help you in part in this way4 ,we will put our candle there1 and place over it a chimney1 thus4 ,i think my candle will go on burning1 because the air-passage is open at the bottom and the top4 ,in the first place1 you see the moisture appearing--that you know about4 ,it is water produced from the candle by the action of the air upon its hydrogen4 ,but1 besides that1 something is going out at the top3 it is not moisture--it is not water--it is not condensable2 and yet1 after all1 it has very singular properties4 ,you will find that the air coming out of the top of our chimney is nearly sufficient to blow the light out ,i am holding to it2 and if ,i put the light fairly opposed to the current1 it will blow it quite out4 ,you will say that is as it should be2 and ,i am supposing that you think it ought to do so1 because the nitrogen does not support combustion1 and ought to put the candle out1 since the candle will not burn in nitrogen4 ,illustration3 ,fig4 #bi4 ,but is there nothing else there than nitrogen8 ,i must now anticipate--that is to say1 ,i must use my own knowledge to supply you with the means that we adopt for the purpose of ascertaining these things1 and examining such gases as these4 ,i will take an empty bottle--here is one--and if ,i hold it over this chimney1 ,i shall get the combustion of the candle below sending its results into the bottle above2 and we shall soon find that this bottle contains1 not merely an air that is bad as regards the combustion of a taper put into it1 but having other properties4 ,let me take a little quick-lime and pour some common water on to it--the commonest water will do4 ,i will stir it a moment1 then pour it upon a piece of filtering paper in a funnel1 and we shall very quickly have a clear water proceeding to the bottle below1 as ,i have here4 ,i have plenty of this water in another bottle2 but1 nevertheless1 ,i should like to use the lime-water that was prepared before you1 so that you may see what its uses are4 ,if ,i take some of this beautiful clear lime-water1 and pour it into this jar1 which has collected the air from the candle1 you will see a change coming about4 ,do you see that the water has become quite milky8 ,observe1 that will not happen with air merely4 ,here is a bottle filled with air2 and if ,i put a little lime-water into it1 neither the oxygen nor the nitrogen1 nor anything else that is in that quantity of air1 will make any change in the lime-water4 ,it remains perfectly clear1 and no shaking of that quantity of lime-water with that quantity of air in its common state will cause any change2 but if ,i take this bottle with the lime-water1 and hold it so as to get the general products of the candle in contact with it1 in a very short time we shall have it milky4 ,there is the chalk1 consisting of the lime which we used in making the lime-water1 combined with something that came from the candle--that other product which we are in search of1 and which ,i want to tell you about to-day4 ,this is a substance made visible to us by its action1 which is not the action of the lime-water either upon the oxygen or upon the nitrogen1 nor upon the water itself1 but it is something new to us from the candle4 ,and then we find this white powder1 produced by the lime-water and the vapour from the candle1 appears to us very much like whitening or chalk1 and1 when examined1 it does prove to be exactly the same substance as whitening or chalk4 ,so we are led1 or have been led1 to observe upon the various circumstances of this experiment1 and to trace this production of chalk to its various causes1 to give us the true knowledge of the nature of this combustion of the candle--to find that this substance1 issuing from the candle1 is exactly the same as that substance which would issue from a retort1 if ,i were to put some chalk into it with a little moisture1 and make it red-hot3 you would then find that exactly the same substance would issue from it as from the candle4 ,but we have a better means of getting this substance1 and in greater quantity1 so as to ascertain what its general characters are4 ,we find this substance in very great abundance in a multitude of cases where you would least expect it4 ,all limestones contain a great deal of this gas which issues from the candle1 and which we call carbonic acid4 ,all chalks1 all shells1 all corals contain a great quantity of this curious air4 ,we find it fixed in these stones2 for which reason ,dr4 ,black called it 8fixed air0--finding it in these fixed things like marble and chalk4 ,he called it fixed air1 because it lost its quality of air1 and assumed the condition of a solid body4 ,we can easily get this air from marble4 ,here is a jar containing a little muriatic acid1 and here is a taper which1 if ,i put it into that jar1 will shew only the presence of common air4 ,there is1 you see1 pure air down to the bottom2 the jar is full of it ,here is a substance--marble#ag1 a very beautiful and superior marble--and if ,i put these pieces of marble into the jar1 a great boiling apparently goes on4 ,that1 however1 is not steam--it is a gas that is rising up2 and if ,i now search the jar by a candle1 ,i shall have exactly the same effect produced upon the taper as ,i had from the air which issued from the end of the chimney over the burning candle4 ,it is exactly the same action1 and caused by the very same substance that issued from the candle2 and in this way we can get carbonic acid in great abundance--we have already nearly filled the jar4 ,we also find that this gas is not merely contained in marble4 ,here is a vessel in which ,i have put some common whitening--chalk1 which has been washed in water and deprived of its coarser particles1 and so supplied to the plasterer as whitening4 ,here is a large jar containing this whitening and water1 and ,i have here some strong sulphuric acid1 which is the acid you might have to use if you were to make these experiments 7only1 in using this acid with limestone1 the body that is produced is an insoluble substance1 whereas the muriatic acid produces a soluble substance that does not so much thicken the water74 ,and you will seek out a reason why ,i take this kind of apparatus for the purpose of shewing this experiment4 ,i do it because you may repeat in a small way what ,i am about to do in a large one4 ,you will have here just the same kind of action2 and ,i am evolving in this large jar carbonic acid1 exactly the same in its nature and properties as the gas which we obtained from the combustion of the candle in the atmosphere4 ,and no matter how different the two methods by which we prepare this carbonic acid1 you will see1 when we get to the end of our subject1 that it is all exactly the same1 whether prepared in the one way or in the other4 ,we will now proceed to the next experiment with regard to this gas4 ,what is its nature8 ,here is one of the vessels full1 and we will try it1 as we have done so many other gases1 by combustion4 ,you see it is not combustible1 nor does it support combustion4 ,neither1 as we know1 does it dissolve much in water1 because we collect it over water very easily4 ,then1 you know that it has an effect1 and becomes white in contact with lime-water2 and when it does become white in that way1 it becomes one of the constituents to make carbonate of lime or limestone4 ,the next thing ,i must shew you is1 that it really does dissolve a little in water1 and therefore that it is unlike oxygen and hydrogen in that respect ,i have here an apparatus by which we can produce this solution4 ,in the lower part of this apparatus is marble and acid1 and in the upper part cold water4 ,the valves are so arranged that the gas can get from one to the other4 ,i will set it in action now1 and you can see the gas bubbling up through the water1 as it has been doing all night long1 and by this time we shall find that we have this substance dissolved in the water4 ,if ,i take a glass and draw off some of the water1 ,i find that it tastes a little acid to the mouth3 it is impregnated with carbonic acid2 and if ,i now apply a little lime-water to it1 that will give us a test of its presence4 ,this water will make the lime-water turbid and white1 which is proof of the presence of carbonic acid4 ,then it is a very weighty gas--it is heavier than the atmosphere4 ,i have put their respective weights at the lower part of this table1 along with1 for comparison1 the weights of the other gases we have been examining3-- ,pint4 ,cubic ,foot4 ,hydrogen1 4 4 4 4 grains4 ounce4 ,oxygen1 4 4 4 4 #aa #a ,nitrogen1 4 4 4 4 #aj #a ,air14 4 4 4 4 4 #aj #a ,carbonic acid1 4 4 #af #a ,a pint of it weighs #af grains1 and a cubic foot weighs #a ounce1 almost two ounces4 ,you can see by many experiments that this is a heavy gas4 ,suppose ,i take a glass containing nothing else but air1 and from this vessel containing the carbonic acid ,i attempt to pour a little of this gas into that glass2 ,i wonder whether any has gone in or not4 ,i cannot tell by the appearance1 but ,i can in this way introducing the taper4 ,yes1 there it is1 you see2 and if ,i were to examine it by lime-water1 ,i should find it by that test also4 ,i will take this little bucket1 and put it down into the well of carbonic acid--indeed1 we too often have real wells of carbonic acid--and now1 if there is any carbonic acid1 ,i must have got to it by this time1 and it will be in this bucket1 which we will examine with a taper4 ,there it is1 you see2 it is full of carbonic acid4 ,illustration3 ,fig4 #cj4 ,there is another experiment by which ,i will shew you its weight4 ,i have here a jar suspended at one end of a balance--it is now equipoised2 but when ,i pour this carbonic acid into the jar on the one side which now contains air1 you will see it sink down at once1 because of the carbonic acid that ,i pour into it4 ,and now1 if ,i examine this jar with the lighted taper1 ,i shall find that the carbonic acid has fallen into it1 and it no longer has any power of supporting the combustion4 ,if ,i blow a soap-bubble1 which of course will be filled with air1 and let it fall into this jar of carbonic acid1 it will float4 ,illustration3 ,fig4 #ca4 ,but ,i shall first of all take one of these little balloons filled with air4 ,i am not quite sure where the carbonic acid is2 we will just try the depth1 and see whereabouts is its level4 ,there1 you see1 we have this bladder floating on the carbonic acid2 and if ,i evolve some more of the carbonic acid1 the bladder will be lifted up higher4 ,there it goes--the jar is nearly full2 and now ,i will see whether ,i can blow a soap-bubble on that1 and float it in the same way4 ,the ,lecturer here blew a soap-bubble1 and allowed it to fall into the jar of carbonic acid1 when it floated in it midway4 ,it is floating1 as the balloon floated1 by virtue of the greater weight of the carbonic acid than of the air4 ,and now1 having so far given you the history of the carbonic acid--as to its sources in the candle1 as to its physical properties and weight--when we next meet ,i shall shew you of what it is composed1 and where it gets its elements from4 ,,lecture ,,vi4 ,,carbon ,,or ,,charcoal--,,coal-,,gas--,,respiration ,,and ,,its ,,analogy ,,to ,,the ,,burning ,,of ,a ,,candle--,,conclusion4 ,a lady1 who honours me by her presence at these ,lectures1 has conferred a still further obligation by sending me these two candles1 which are from ,japan1 and1 ,i presume1 are made of that substance to which ,i referred in a former lecture4 ,you see that they are even far more highly ornamented than the ,french candles2 and1 ,i suppose1 are candles of luxury1 judging from their appearance4 ,they have a remarkable peculiarity about them--namely1 a hollow wick1--that beautiful peculiarity which ,argand introduced into the lamp1 and made so valuable4 ,to those who receive such presents from the ,east1 ,i may just say that this and such like materials gradually undergo a change which gives them on the surface a dull and dead appearance2 but they may easily be restored to their original beauty1 if the surface be rubbed with a clean cloth or silk handkerchief1 so as to polish the little rugosity or roughness3 this will restore the beauty of the colours4 ,i have so rubbed one of these candles1 and you see the difference between it and the other which has not been polished1 but which may be restored by the same process4 ,observe1 also1 that these moulded candles from ,japan are made more conical than the moulded candles in this part of the world4 ,i told you1 when we last met1 a good deal about carbonic acid4 ,we found1 by the lime-water test1 that when the vapour from the top of the candle or lamp was received into bottles1 and tested by this solution of lime-water 7the composition of which ,i explained to you1 and which you can make for yourselves71 we had that white opacity which was in fact calcareous matter1 like shells and corals1 and many of the rocks and minerals in the earth4 ,but ,i have not yet told you fully and clearly the chemical history of this substance--carbonic acid--as we have it from the candle1 and ,i must now resume that subject4 ,we have seen the products1 and the nature of them1 as they issue from the candle4 ,we have traced the water to its elements1 and now we have to see where are the elements of the carbonic acid supplied by the candle4 ,a few experiments will shew this4 ,you remember that when a candle burns badly1 it produces smoke2 but if it is burning well1 there is no smoke4 ,and you know that the brightness of the candle is due to this smoke1 which becomes ignited4 ,here is an experiment to prove this3 so long as the smoke remains in the flame of the candle and becomes ignited1 it gives a beautiful light1 and never appears to us in the form of black particles4 ,i will light some fuel1 which is extravagant in its burning4 ,this will serve our purpose--a little turpentine on a sponge4 ,you see the smoke rising from it1 and floating into the air in large quantities2 and1 remember now1 the carbonic acid that we have from the candle is from such smoke as that4 ,to make that evident to you1 ,i will introduce this turpentine burning on the sponge into a flask where ,i have plenty of oxygen1 the rich part of the atmosphere1 and you now see that the smoke is all consumed4 ,this is the first part of our experiment2 and now1 what follows8 ,the carbon which you saw flying off from the turpentine flame in the air is now entirely burned in this oxygen1 and we shall find that it will1 by this rough and temporary experiment1 give us exactly the same conclusion and result as we had from the combustion of the candle4 ,the reason why ,i make the experiment in this manner is solely that ,i may cause the steps of our demonstration to be so simple that you can never for a moment lose the train of reasoning1 if you only pay attention4 ,all the carbon which is burned in oxygen1 or air1 comes out as carbonic acid1 whilst those particles which are not so burned shew you the second substance in the carbonic acid--namely1 the carbon--that body which made the flame so bright whilst there was plenty of air1 but which was thrown off in excess when there was not oxygen enough to burn it4 ,i have also to shew you a little more distinctly the history of carbon and oxygen1 in their union to make carbonic acid4 ,you are now better able to understand this than before1 and ,i have prepared three or four experiments by way of illustration4 ,this jar is filled with oxygen1 and here is some carbon which has been placed in a crucible1 for the purpose of being made red-hot4 ,i keep my jar dry1 and venture to give you a result imperfect in some degree1 in order that ,i may make the experiment brighter4 ,i am about to put the oxygen and the carbon together4 ,that this is carbon 7common charcoal pulverised71 you will see by the way in which it burns in the air letting some of the red-hot charcoal fall out of the crucible4 ,i am now about to burn it in oxygen gas1 and look at the difference4 ,it may appear to you at a distance as if it were burning with a flame2 but it is not so4 ,every little piece of charcoal is burning as a spark1 and whilst it so burns it is producing carbonic acid4 ,i specially want these two or three experiments to point out what ,i shall dwell upon more distinctly by-and-by--that carbon burns in this way1 and not as a flame4 ,instead of taking many particles of carbon to burn1 ,i will take a rather large piece1 which will enable you to see the form and size2 and to trace the effects very decidedly4 ,here is the jar of oxygen1 and here is the piece of charcoal1 to which ,i have fastened a little piece of wood1 which ,i can set fire to1 and so commence the combustion1 which ,i could not conveniently do without4 ,you now see the charcoal burning1 but not as a flame 7or if there be a flame1 it is the smallest possible one1 which ,i know the cause of--namely1 the formation of a little carbonic oxide close upon the surface of the carbon74 ,it goes on burning1 you see1 slowly producing carbonic acid by the union of this carbon or charcoal 7they are equivalent terms7 with the oxygen4 ,i have here another piece of charcoal1 a piece of bark1 which has the quality of being blown to pieces--exploding as it burns4 ,by the effect of the heat1 we shall reduce the lump of carbon into particles that will fly off2 still every particle1 equally with the whole mass1 burns in this peculiar way3 it burns as a coal1 and not like a flame4 ,you observe a multitude of little combustions going on1 but no flame4 ,i do not know a finer experiment than this1 to shew that carbon burns with a spark4 ,here1 then1 is carbonic acid formed from its elements4 ,it is produced at once2 and if we examined it by lime-water1 you will see that we have the same substance which ,i have previously described to you4 ,by putting together #f parts of carbon by weight 7whether it comes from the flame of a candle or from powdered charcoal7 and #af parts of oxygen by weight1 we have #bb parts of carbonic acid2 and1 as we saw last time1 the #bb parts of carbonic acid1 combined with #bh parts of lime1 produced common carbonate of lime4 ,if you were to examine an oyster-shell1 and weigh the component parts1 you would find that every #ej parts would give #f of carbon and #af of oxygen1 combined with #bh of lime4 ,however1 ,i do not want to trouble you with these minuti--it is only the general philosophy of the matter that we can now go into4 ,see how finely the carbon is dissolving away pointing to the lump of charcoal burning quietly in the jar of oxygen4 ,you may say that the charcoal is actually dissolving in the air round about2 and if that were perfectly pure charcoal1 which we can easily prepare1 there would be no residue whatever4 ,when we have a perfectly cleansed and purified piece of carbon1 there is no ash left4 ,the carbon burns as a solid dense body1 that heat alone cannot change as to its solidity1 and yet it passes away into vapour that never condenses into solid or liquid under ordinary circumstances2 and what is more curious still1 is the fact that the oxygen does not change in its bulk by the solution of the carbon in it4 ,just as the bulk is at first1 so it is at last1 only it has become carbonic acid4 ,there is another experiment which ,i must give you before you are fully acquainted with the general nature of carbonic acid4 ,being a compound body1 consisting of carbon and oxygen1 carbonic acid is a body that we ought to be able to take asunder4 ,and so we can4 ,as we did with water1 so we can with carbonic acid--take the two parts asunder4 ,the simplest and quickest way is to act upon the carbonic acid by a substance that can attract the oxygen from it1 and leave the carbon behind4 ,you recollect that ,i took potassium and put it upon water or ice1 and you saw that it could take the oxygen from the hydrogen4 ,now1 suppose we do something of the same kind here with this carbonic acid4 ,you know carbonic acid to be a heavy gas4 ,i will not test it with lime-water1 as that will interfere with our subsequent experiments2 but ,i think the heaviness of the gas and the power of extinguishing flame will be sufficient for our purpose4 ,i introduce a flame into the gas1 and you will see whether it will be put out4 ,you see the light is extinguished4 ,indeed1 the gas may1 perhaps1 put out phosphorus1 which1 you know1 has a pretty strong combustion4 ,here is a piece of phosphorus heated to a high degree4 ,i introduce it into gas1 and you observe the light is put out2 but it will take fire again in the air1 because there it re-enters into combustion4 ,now1 let me take a piece of potassium1 a substance which1 even at common temperatures1 can act upon carbonic acid1 though not sufficiently for our present purpose1 because it soon gets covered with a protecting coat2 but if we warm it up to the burning point in air1 as we have a fair right to do1 and as we have done with phosphorus1 you will see that it can burn in carbonic acid2 and if it burns1 it will burn by taking oxygen1 so that you will see what is left behind4 ,i am going1 then1 to burn this potassium in the carbonic acid1 as a proof of the existence of oxygen in the carbonic acid4 ,in the preliminary process of heating1 the potassium exploded4 ,sometimes we get an awkward piece of potassium that explodes1 or something like it1 when it burns4 ,i will take another piece2 and now that it is heated1 ,i introduce it into the jar1 and you perceive that it burns in the carbonic acid--not so well as in the air1 because the carbonic acid contains the oxygen combined2 but it does burn1 and takes away the oxygen4 ,if ,i now put this potassium into water1 ,i find that1 besides the potash formed 7which you need not trouble about71 there is a quantity of carbon produced4 ,i have here made the experiment in a very rough way2 but ,i assure you that if ,i were to make it carefully1 devoting a day to it1 instead of five minutes1 we should get all the proper amount of charcoal left in the spoon1 or in the place where the potassium was burned1 so that there could be no doubt as to the result4 ,here1 then1 is the carbon obtained from the carbonic acid1 as a common black substance2 so that you have the entire proof of the nature of carbonic acid as consisting of carbon and oxygen4 ,and now1 ,i may tell you1 that whenever carbon burns under common circumstances1 it produces carbonic acid4 ,suppose ,i take this piece of wood1 and put it into a bottle with lime-water4 ,i might shake that lime-water up with wood and the atmosphere as long as ,i pleased1 it would still remain clear as you see it2 but suppose ,i burn the piece of wood in the air of that bottle4 ,you1 of course1 know ,i get water4 ,do ,i get carbonic acid8 ,the experiment was performed4 ,there it is1 you see--that is to say1 the carbonate lime1 which results from carbonic acid1 and that carbonic acid must be formed from the carbon which comes from the wood1 from the candle1 or any other thing4 ,indeed1 you have yourselves frequently tried a very pretty experiment1 by which you may see the carbon in wood4 ,if you take a piece of wood1 and partly burn it1 and then blow it out1 you have carbon left4 ,there are things that do not shew carbon in this way4 ,a candle does not shew it1 but it contains carbon4 ,here also is a jar of coal-gas1 which produces carbonic acid abundantly4 ,you do not see the carbon1 but we can soon shew it to you4 ,i will light it1 and as long as there is any gas in this cylinder it will go on burning4 ,you see no carbon1 but you see a flame2 and because that is bright1 it will lead you to guess that there is carbon in the flame4 ,but ,i will shew it to you by another process4 ,i have some of the same gas in another vessel1 mixed with a body that will burn the hydrogen of the gas1 but will not burn the carbon4 ,i will light them with a burning taper1 and you perceive the hydrogen is consumed1 but not the carbon1 which is left behind as a dense black smoke4 ,i hope that by these three or four experiments you will learn to see when carbon is present1 and understand what are the products of combustion1 when gas or other bodies are thoroughly burned in the air4 ,before we leave the subject of carbon1 let us make a few experiments and remarks upon its wonderful condition as respects ordinary combustion4 ,i have shewn you that the carbon in burning burns only as a solid body1 and yet you perceive that1 after it is burned1 it ceases to be a solid4 ,there are very few fuels that act like this4 ,it is1 in fact1 only that great source of fuel1 the carbonaceous series1 the coals1 charcoals1 and woods1 that can do it4 ,i do not know that there is any other elementary substance besides carbon that burns with these conditions2 and if it had not been so1 what would happen to us8 ,suppose all fuel had been like iron1 which1 when it burns1 burns into a solid substance4 ,we could not then have such a combustion as you have in this fireplace4 ,here also is another kind of fuel which burns very well--as well as1 if not better1 than carbon--so well1 indeed1 as to take fire of itself when it is in the air1 as you see breaking a tube full of lead pyrophorus4 ,this substance is lead1 and you see how wonderfully combustible it is4 ,it is very much divided1 and is like a heap of coals in the fireplace2 the air can get to its surface and inside1 and so it burns4 ,but why does it not burn in that way now1 when it is lying in a mass8 emptying the contents of the tube in a heap on to a plate of iron4 ,simply because the air cannot get to it4 ,though it can produce a great heat1 the great heat which we want in our furnaces and under our boilers1 still that which is produced cannot get away from the portion which remains unburned underneath1 and that portion1 therefore1 is prevented from coming in contact with the atmosphere1 and cannot be consumed4 ,how different is that from carbon4 ,carbon burns just in the same way as this lead does1 and so gives an intense fire in the furnace1 or wherever you choose to burn it2 but then the body produced by its combustion passes away1 and the remaining carbon is left clear4 ,i shewed you how carbon went on dissolving in the oxygen1 leaving no ash2 whereas here pointing to the heap of pyrophorus we have actually more ash than fuel1 for it is heavier by the amount of the oxygen which has united with it4 ,thus you see the difference between carbon and lead or iron3 if we choose iron1 which gives so wonderful a result in our application of this fuel1 either as light or heat4 ,if1 when the carbon burnt1 the product went off as a solid body1 you would have had the room filled with an opaque substance1 as in the case of the phosphorus2 but when carbon burns1 everything passes up into the atmosphere4 ,it is in a fixed1 almost unchangeable condition before the combustion2 but afterwards it is in the form of gas1 which it is very difficult 7though we have succeeded7 to produce in a solid or a liquid state4 ,now1 ,i must take you to a very interesting part of our subject--to the relation between the combustion of a candle and that living kind of combustion which goes on within us4 ,in every one of us there is a living process of combustion going on very similar to that of a candle2 and ,i must try to make that plain to you4 ,for it is not merely true in a poetical sense--the relation of the life of man to a taper2 and if you will follow1 ,i think ,i can make this clear4 ,in order to make the relation very plain1 ,i have devised a little apparatus which we can soon build up before you4 ,here is a board and a groove cut in it1 and ,i can close the groove at the top part by a little cover4 ,i can then continue the groove as a channel by a glass tube at each end1 there being a free passage through the whole4 ,suppose ,i take a taper or candle 7we can now be liberal in our use of the word 8candle10 since we understand what it means71 and place it in one of the tubes2 it will go on1 you see1 burning very well4 ,you observe that the air which feeds the flame passes down the tube at one end1 then goes along the horizontal tube1 and ascends the tube at the other end in which the taper is placed4 ,illustration3 ,fig4 #cb ,if ,i stop the aperture through which the air enters1 ,i stop combustion1 as you perceive4 ,i stop the supply of air1 and consequently the candle goes out4 ,but1 now1 what will you think of this fact8 ,in a former experiment ,i shewed you the air going from one burning candle to a second candle4 ,if ,i took the air proceeding from another candle1 and sent it down by a complicated arrangement into this tube1 ,i should put this burning candle out4 ,but what will you say when ,i tell you that my breath will put out that candle8 ,i do not mean by blowing at all1 but simply that the nature of my breath is such that a candle cannot burn in it4 ,i will now hold my mouth over the aperture1 and without blowing the flame in any way1 let no air enter the tube but what comes from my mouth4 ,you see the result4 ,i did not blow the candle out4 ,i merely let the air which ,i expired pass into the aperture1 and the result was that the light went out for want of oxygen1 and for no other reason4 ,something or other--namely1 my lungs--had taken away the oxygen from the air1 and there was no more to supply the combustion of the candle4 ,it is1 ,i think1 very pretty to see the time it takes before the bad air which ,i throw into this part of the apparatus has reached the candle4 ,the candle at first goes on burning1 but so soon as the air has had time to reach it1 it goes out4 ,and1 now1 ,i will shew you another experiment1 because this is an important part of our philosophy4 ,here is a jar which contains fresh air1 as you can see by the circumstance of a candle or gas-light burning it4 ,i make it close for a little time1 and by means of a pipe ,i get my mouth over it so that ,i can inhale the air4 ,by putting it over water1 in the way that you see1 ,i am able to draw up this air 7supposing the cork to be quite tight71 take it into my lungs1 and throw it back into the jar4 ,illustration3 ,fig4 #cc4 ,we can then examine it1 and see the result4 ,you observe1 ,i first take up the air1 and then throw it back1 as is evident from the ascent and descent of the water2 and now1 by putting a taper into the air1 you will see the state in which it is1 by the light being extinguished4 ,even one inspiration1 you see1 has completely spoiled this air1 so that it is no use my trying to breathe it a second time4 ,now1 you understand the ground of the impropriety of many of the arrangements among the houses of the poorer classes1 by which the air is breathed over and over again1 for the want of a supply1 by means of proper ventilation1 sufficient to produce a good result4 ,you see how bad the air becomes by a single breathing2 so that you can easily understand how essential fresh air is to us4 ,to pursue this a little further1 let us see what will happen with lime-water4 ,here is a globe which contains a little lime-water1 and it is so arranged as regards the pipes1 as to give access to the air within1 so that we can ascertain the effect of respired or unrespired air upon it4 ,of course1 ,i can either draw in air 7through ,a71 and so make the air that feeds my lungs go through the lime-water1 or ,i can force the air out of my lungs through the tube 7,b71 which goes to the bottom1 and so shew its effect upon the lime-water4 ,illustration3 ,fig4 #cd4 ,you will observe that1 however long ,i draw the external air into the lime-water1 and then through it to my lungs1 ,i shall produce no effect upon the water--it will not make the lime-water turbid2 but if ,i throw the air from my lungs through the lime-water1 several times in succession1 you see how white and milky the water is getting1 shewing the effect which expired air has had upon it2 and now you begin to know that the atmosphere which we have spoiled by respiration is spoiled by carbonic acid1 for you see it here in contact with the lime-water4 ,i have here two bottles1 one containing lime-water and the other common water1 and tubes which pass into the bottles and connect them4 ,the apparatus is very rough1 but it is useful notwithstanding4 ,illustration3 ,fig4 #ce4 ,if ,i take these two bottles1 inhaling here and exhaling there1 the arrangement of the tubes will prevent the air going backwards4 ,the air coming in will go to my mouth and lungs1 and in going out1 will pass through the lime-water1 so that ,i can go on breathing and making an experiment1 very refined in its nature1 and very good in its results4 ,you will observe that the good air has done nothing to the lime-water2 in the other case nothing has come to the lime-water but my respiration1 and you see the difference in the two cases4 ,let us now go a little further4 ,what is all this process going on within us which we cannot do without1 either day or night1 which is so provided for by the ,author of all things that ,he has arranged that it shall be independent of all will8 ,if we restrain our respiration1 as we can to a certain extent1 we should destroy ourselves4 ,when we are asleep1 the organs of respiration1 and the parts that are associated with them1 still go on with their action--so necessary is this process of respiration to us1 this contact of the air with the lungs4 ,i must tell you1 in the briefest possible manner1 what this process is4 ,we consume food3 the food goes through that strange set of vessels and organs within us1 and is brought into various parts of the system1 into the digestive parts especially2 and alternately the portion which is so changed is carried through our lungs by one set of vessels1 while the air that we inhale and exhale is drawn into and thrown out of the lungs by another set of vessels1 so that the air and the food come close together1 separated only by an exceedingly thin surface3 the air can thus act upon the blood by this process1 producing precisely the same results in kind as we have seen in the case of the candle4 ,the candle combines with parts of the air1 forming carbonic acid1 and evolves heat2 so in the lungs there is this curious1 wonderful change taking place4 ,the air entering1 combines with the carbon 7not carbon in a free state1 but1 as in this case1 placed ready for action at the moment71 and makes carbonic acid1 and is so thrown out into the atmosphere1 and thus this singular result takes place3 we may thus look upon the food as fuel4 ,let me take that piece of sugar1 which will serve my purpose4 ,it is a compound of carbon1 hydrogen1 and oxygen1 similar to a candle1 as containing the same elements1 though not in the same proportion--the proportions being as shewn in this table3-- ,,sugar4 ,carbon1 4 4 4 4 #gb ,hydrogen1 4 4 4 #aa #ii ,oxygen1 4 4 4 4 #hh ,this is1 indeed1 a very curious thing1 which you can well remember1 for the oxygen and hydrogen are in exactly the proportions which form water1 so that sugar may be said to be compounded of #gb parts of carbon and #ii parts of water2 and it is the carbon in the sugar that combines with the oxygen carried in by the air in the process of respiration--so making us like candles--producing these actions1 warmth1 and far more wonderful results besides1 for the sustenance of the system1 by a most beautiful and simple process4 ,to make this still more striking1 ,i will take a little sugar2 or1 to hasten the experiment1 ,i will use some syrup1 which contains about three-fourths of sugar and a little water4 ,if ,i put a little oil of vitriol on it1 it takes away the water1 and leaves the carbon in a black mass4 ,the ,lecturer mixed the two together4 ,you see how the carbon is coming out1 and before long we shall have a solid mass of charcoal1 all of which has come out of sugar4 ,sugar1 as you know1 is food1 and here we have absolutely a solid lump of carbon where you would not have expected it4 ,and if ,i make arrangements so as to oxidize the carbon of sugar1 we shall have a much more striking result ,here is sugar1 and ,i have here an oxidizer--a quicker one than the atmosphere2 and so we shall oxidize this fuel by a process different from respiration in its form1 though not different in its kind4 ,it is the combustion of the carbon by the contact of oxygen which the body has supplied to it4 ,if ,i set this into action at once1 you will see combustion produced4 ,just what occurs in my lungs--taking in oxygen from another source1 namely1 the atmosphere--takes place here by a more rapid process4 ,you will be astonished when ,i tell you what this curious play of carbon amounts to4 ,a candle will burn some four1 five1 six1 or seven hours4 ,what1 then1 must be the daily amount of carbon going up into the air in the way of carbonic acid6 ,what a quantity of carbon must go from each of us in respiration6 ,what a wonderful change of carbon must take place under these circumstances of combustion or respiration6 ,a man in twenty-four hours converts as much as seven ounces of carbon into carbonic acid2 a milch cow will convert seventy ounces1 and a horse seventy-nine ounces1 solely by the act of respiration4 ,that is1 the horse in twenty-four hours burns seventy-nine ounces of charcoal1 or carbon1 in his organs of respiration1 to supply his natural warmth in that time4 ,all the warm-blooded animals get their warmth in this way1 by the conversion of carbon1 not in a free state1 but in a state of combination4 ,and what an extraordinary notion this gives us of the alterations going on in our atmosphere4 ,as much as #e1jjj1jjj pounds1 or #edh tons1 of carbonic acid is formed by respiration in ,london alone in twenty-four hours4 ,and where does all this go8 ,up into the air4 ,if the carbon had been like the lead which ,i shewed you1 or the iron which1 in burning1 produces a solid substance1 what would happen8 ,combustion could not go on4 ,as charcoal burns1 it becomes a vapour and passes off into the atmosphere1 which is the great vehicle1 the great carrier for conveying it away to other places4 ,then1 what becomes of it8 ,wonderful is it to find that the change produced by respiration1 which seems so injurious to us 7for we cannot breathe air twice over71 is the very life and support of plants and vegetables that grow upon the surface of the earth4 ,it is the same also under the surface1 in the great bodies of water2 for fishes and other animals respire upon the same principle1 though not exactly by contact with the open air4 ,such fish as ,i have here pointing to a globe of gold-fish respire by the oxygen which is dissolved from the air by the water1 and form carbonic acid2 and they all move about to produce the one great work of making the animal and vegetable kingdoms subservient to each other4 ,and all the plants growing upon the surface of the earth1 like that which ,i have brought here to serve as an illustration1 absorb carbon4 ,these leaves are taking up their carbon from the atmosphere1 to which we have given it in the form of carbonic acid1 and they are growing and prospering4 ,give them a pure air like ours1 and they could not live in it2 give them carbon with other matters1 and they live and rejoice4 ,this piece of wood gets all its carbon1 as the trees and plants get theirs1 from the atmosphere1 which1 as we have seen1 carries away what is bad for us and at the same time good for them1--what is disease to the one being health to the other4 ,so are we made dependent1 not merely upon our fellow-creatures1 but upon our fellow-existers1 all ,nature being tied together by the laws that make one part conduce to the good of another4 ,there is another little point which ,i must mention before we draw to a close--a point which concerns the whole of these operations1 and most curious and beautiful it is to see it clustering upon and associated with the bodies that concern us--oxygen1 hydrogen1 and carbon1 in different states of their existence4 ,i shewed you just now some powdered lead1 which ,i set burning#ah2 and you saw that the moment the fuel was brought to the air1 it acted1 even before it got out of the bottle--the moment the air crept in1 it acted4 ,now1 there is a case of chemical affinity by which all our operations proceed4 ,when we breathe1 the same operation is going on within us4 ,when we burn a candle1 the attraction of the different parts one to the other is going on4 ,here it is going on in this case of the lead2 and it is a beautiful instance of chemical affinity4 ,if the products of combustion rose off from the surface1 the lead would take fire1 and go on burning to the end2 but you remember that we have this difference between charcoal and lead--that1 while the lead can start into action at once1 if there be access of air to it1 the carbon will remain days1 weeks1 months1 or years4 ,the manuscripts of ,herculaneum were written with carbonaceous ink1 and there they have been for #a1hjj years or more1 not having been at all changed by the atmosphere1 though coming in contact with it under various circumstances4 ,now1 what is the circumstance which makes the lead and carbon differ in this respect8 ,it is a striking thing to see that the matter which is appointed to serve the purpose of fuel waits in its action3 it does not start off burning1 like the lead and many other things that ,i could shew you2 but which ,i have not encumbered the table with2 but it waits for action4 ,this waiting is a curious and wonderful thing4 ,candles--those ,japanese candles1 for instance--do not start into action at once1 like the lead or iron 7for iron finely divided does the same thing as lead71 but there they wait for years1 perhaps for ages1 without undergoing any alteration4 ,i have here a supply of coal-gas4 ,the jet is giving forth the gas1 but you see it does not take fire--it comes out into the air1 but it waits till it is hot enough before it burns4 ,if ,i make it hot enough1 it takes fire4 ,if ,i blow it out1 the gas that is issuing forth waits till the light is applied to it again4 ,it is curious to see how different substances wait--how some will wait till the temperature is raised a little1 and others till it is raised a good deal4 ,i have here a little gunpowder and some gun-cotton2 even these things differ in the conditions under which they will burn4 ,the gunpowder is composed of carbon and other substances1 making it highly combustible2 and the gun-cotton is another combustible preparation4 ,they are both waiting1 but they will start into activity at different degrees of heat1 or under different conditions4 ,by applying a heated wire to them1 we shall see which will start first touching the gun-cotton with the hot iron4 ,you see the gun-cotton has gone off1 but not even the hottest part of the wire is now hot enough to fire the gunpowder4 ,how beautifully that shews you the difference in the degree in which bodies act in this way6 ,in the one case the substance will wait any time until the associated bodies are made active by heat2 but in the other1 as in the process of respiration1 it waits no time4 ,in the lungs1 as soon as the air enters1 it unites with the carbon2 even in the lowest temperature which the body can bear short of being frozen1 the action begins at once1 producing the carbonic acid of respiration3 and so all things go on fitly and properly4 ,thus you see the analogy between respiration and combustion is rendered still more beautiful and striking4 ,indeed1 all ,i can say to you at the end of these lectures 7for we must come to an end at one time or other7 is to express a wish that you may1 in your generation1 be fit to compare to a candle2 that you may1 like it1 shine as lights to those about you2 that1 in all your actions1 you may justify the beauty of the taper by making your deeds honourable and effectual in the discharge of your duty to your fellow-men4 ,,lecture ,,on ,,platinum4 ,delivered before the ,,royal ,,institution1 on ,friday1 ,february #bb1 #ahfa4 ,whether ,i was to have the honour of appearing before you this evening or not1 seemed to be doubtful upon one or two points4 ,one of these ,i will mention immediately2 the other may or may not appear during the course of the hour that follows4 ,the first point is this4 ,when ,i was tempted to promise this subject for your attention this evening1 it was founded upon a promise1 and a full intent of performing that promise1 on the part of my friend ,deville1 of ,paris1 to come here to shew before you a phenomenon in metallurgic chemistry not common4 ,in that ,i have been disappointed4 ,his intention was to have fused here some thirty or forty pounds of platinum1 and so to have made manifest1 through my mouth and my statement1 the principles of a new process in metallurgy1 in relation to this beautiful1 magnificent1 and valuable metal2 but circumstances over which neither he nor ,i1 nor others concerned1 have sufficient control1 have prevented the fulfilment of that intention2 and the period at which ,i learned the fact was so recent1 that ,i could hardly leave my place here to be filled by another1 or permit you1 who in your kindness have come to hear what might be said1 to remain unreceived in the best manner possible to me under the circumstances4 ,i therefore propose to state1 as well as ,i can1 what the principles are on which ,m4 ,deville proceeds1 by means of drawings1 and some subordinate or inferior experiments4 ,the metal platinum1 of which you see some very fine specimens on the table1 has been known to us about a hundred years4 ,it has been wrought in a beautiful way in this country1 in ,france1 and elsewhere1 and supplied to the consumer in ingots of this kind1 or in plates1 such as we have here1 or in masses1 that by their very fall upon the table indicate the great weight of the substance1 which is1 indeed1 nearly at the head of all substances in that respect4 ,this substance has been given to us hitherto mainly through the philosophy of ,dr4 ,wollaston1 whom many of us know1 and it is obtained in great purity and beauty4 ,it is a very remarkable metal in many points1 besides its known special uses4 ,it usually comes to us in grains4 ,here is a very fine specimen of native platinum in grains4 ,here is also a nugget or ingot1 and here are some small pieces gathered out of certain alluvial soils in ,brazil1 ,mexico1 ,california1 and the ,uralian districts of ,russia4 ,it is strange that this metal is almost always found associated with some four or five other metals1 most curious in their qualities and characteristics4 ,they are called platiniferous metals2 and they have not only the relation of being always found associated in this manner1 but they have other relations of a curious nature1 which ,i shall point out to you by a reference to one of the tables behind me4 ,this substance is always native--it is always in the metallic state2 and the metals with which it is found connected1 and which are rarely found elsewhere1 are palladium1 rhodium1 iridium1 osmium1 and ruthenium4 ,we have the names in one of the tables arranged in two columns1 representing1 as you see1 two groups--platinum1 iridium1 and osmium constituting one group2 and ruthenium1 rhodium1 and palladium the other4 ,three of these have the chemical equivalent of #ih1 and the others a chemical equivalent of about half that number4 ,then the metals of one group have an extreme specific gravity--platinum being1 in fact1 the lightest of the three1 or as light as the lightest4 ,osmium has a specific gravity of #ba4d1 and is the heaviest body in nature2 platinum is #ba4ae1 and iridium the same2 the specific gravity of the other three being only about half that1 namely1 #aa4c1 #ab4a1 and #aa4h4 ,then there is this curious relation1 that palladium and iridium are very much alike1 so that you would scarcely know one from the other1 though one has only half the weight of the other1 and only half the equivalent power4 ,so with iridium and rhodium1 and osmium and ruthenium1 which are so closely allied that they make pairs1 being separated each from its own group4 ,then these metals are the most infusible that we possess4 ,osmium is the most difficult to fuse3 indeed1 ,i believe it never has been fused1 while every other metal has4 ,ruthenium comes next1 iridium next1 rhodium next1 platinum next 7so that it ranks here as a pretty fusible metal1 and yet we have been long accustomed to speak of the infusibility of platinum71 and next comes palladium1 which is the most fusible metal of the whole4 ,it is a curious thing to see this fine association of physical properties coming out in metals which are grouped together somehow or other in nature1 but1 no doubt1 by causes which are related to analogous properties in their situation on the surface of the earth1 for it is in alluvial soils that these things are found4 ,now1 with regard to this substance1 let me tell you briefly how we get it4 ,the process used to be this4 ,the ore which ,i shewed you just now was taken1 and digested in nitro-muriatic acid of a certain strength1 and partly converted into a solution1 with the leaving behind of certain bodies that ,i have upon the table4 ,the platinum being dissolved with care in acids1 to the solution the muriate of ammonia was added1 as ,i am about to add it here4 ,a yellow precipitate was then thrown down1 as you perceive is the case now2 and this1 carefully washed and cleansed1 gave us that body pointing to a specimen of the chloride of platinum and ammonium1 the other elements1 or nearly all1 being ejected4 ,this substance being heated1 gave us what we call platinum sponge1 or platinum in the metallic state1 so finely divided as to form a kind of heavy mass or sponge1 which1 at the time that ,dr4 ,wollaston first sent it forth1 was not fusible for the market or in the manufacturers' workshops1 inasmuch as the temperature required was so high1 and there were no furnaces that could bring the mass into a globule1 and cause the parts to adhere together4 ,most of our metals that we obtain from nature1 and work in our shops1 are brought at last into a mass by fusion4 ,i am not aware that there is in the arts or sciences any other than iron which is not so4 ,soft iron we do not bring together by fusion1 but by a process which is analogous to the one that was followed in the case of platinum1 namely1 welding2 for these divided grains of spongy platinum having been well washed and sunk in water for the purpose of excluding air1 and pressed together1 and heated1 and hammered1 and pressed again1 until they come into a pretty close1 dense1 compact mass1 did so cohere1 that when the mass was put into the furnace of charcoal1 and raised to a high temperature1 the particles1 at first infinitely divided--for they were chemically divided--adhered the one to the other1 each to all the rest1 until they made that kind of substance which you see here1 which will bear rolling and expansion of every kind4 ,no other process than that has hitherto been adopted for the purpose of obtaining this substance from the particles by solution1 precipitation1 ignition1 and welding4 ,it certainly is a very fine thing to see that we may so fully depend upon the properties of the various substances we have to deal with2 that we can1 by carrying out our processes1 obtain a material like this1 allowing of division and extension under a rolling mill--a material of the finest possible kind1 the parts being held together1 not with interstices1 not with porosity1 but so continuous that no fluids can pass between them2 and1 as ,dr4 ,wollaston beautifully shewed1 a globule of platinum fused by the voltaic battery and the oxyhydrogen blowpipe1 when drawn into a wire1 was not sounder or stronger than this wire made by the curious coalescence of the particles by the sticking power that they had at high temperatures4 ,this is the process adopted by ,messrs4 ,johnson and ,matthey1 to whose great kindness ,i am indebted for these ingots and for the valuable assistance ,i have received in the illustrations4 ,the treatment1 however1 that ,i have to bring before you is of another kind2 and it is in the hope that we shall be able before long to have such a thing as the manufacture of platinum of this kind1 that ,i am encouraged to come before you1 and tell you how far ,deville has gone in the matter1 and to give you illustrations of the principles on which he proceeds4 ,i think it is but fair that you should see an experiment shewing you the way in which we get the adhesion of platinum4 ,probably you all know of the welding of iron3 you go into the smith's shop1 and you see him put the handle of a poker on to the stem1 and by a little management and the application of heat he makes them one4 ,you have no doubt seen him put the iron into the fire and sprinkle a little sand upon it4 ,he does not know the philosophy he calls into play when he sprinkles a little sand over the oxide of iron1 but he has a fine philosophy there1 or practises it1 when he gets his welding4 ,i can shew you here this beautiful circumstance of the sticking together of the particles up to the fullest possible intensity of their combination4 ,if you were to go into the workshops of ,mr4 ,matthey1 and see them hammering and welding away1 you would see the value of the experiment ,i am about to shew you4 ,i have here some platinum-wire4 ,this is a metal which resists the action of acids1 resists oxidation by heat1 and change of any sort2 and which1 therefore1 ,i may heat in the atmosphere without any flux4 ,i bend the wire so as to make the ends cross3 these ,i make hot by means of the blowpipe1 and then1 by giving them a tap with a hammer1 ,i shall make them into one piece4 ,now that the pieces are united1 ,i shall have great difficulty in pulling them apart1 though they are joined only at the point where the two cylindrical surfaces came together4 ,and now ,i have succeeded in pulling the wire apart1 the division is not at the point of welding1 but where the force of the pincers has cut it1 so that the junction we have effected is a complete one4 ,this1 then1 is the principle of the manufacture and production of platinum in the old way4 ,the treatment which ,deville proposes to carry out1 and which he has carried out to a rather large extent in reference to the ,russian supply of platinum1 is one altogether by heat1 having little or no reference to the use of acids4 ,that you may know what the problem is1 look at this table1 which gives you the composition of such a piece of platinum ore as ,i shewed you just now4 ,wherever it comes from1 the composition is as complicated1 though the proportions vary3-- ,platinum1 4 4 4 4 4 #gf4d ,iridium14 4 4 4 4 4 #d4c ,rhodium14 4 4 4 4 4 #j4c ,palladium14 4 4 4 4 #a4d ,gold1 4 4 4 4 4 4 4 #j4d ,copper1 4 4 4 4 4 4 #d4a ,iron1 4 4 4 4 4 4 4 #aa4g ,osmide of ,iridium14 #j4e ,sand1 4 4 4 4 4 4 4 #a4d ---------- #ajj4e ,this refers to the ,uralian ore4 ,in that state of combination1 as shewn in the table1 the iridium and osmium are found combined in crystals1 sometimes to the amount of #j4e per cent41 and sometimes #c or #d per cent4 ,now1 this ,deville proposes to deal with in the dry way1 in the place of dealing with it by any acid4 ,i have here another kind of platinum2 and ,i shew it to you for this reason4 ,the ,russian ,government1 having large stores of platinum in their dominions1 have obtained it in a metallic state1 and worked it into coin4 ,the coin ,i have in my hand is a twelve silver rouble piece4 ,the rouble is worth three shillings1 and this coin is1 therefore1 of the value of thirty-six shillings4 ,the smaller coin is worth half that sum2 and the other1 half of that4 ,the metal1 however1 is unfit for coinage4 ,when you have the two metals1 gold and silver1 used for coinage1 you have a little confusion in the value of the two in the market2 but when you have three precious metals 7for you may call platinum a precious metal7 worked into coin1 they will be sure to run counter to one another4 ,indeed1 the case did happen1 that the price of platinum coin fixed by the ,government was such1 that it was worth while to purchase platinum in other countries1 and make coin of it1 and then take it into that country and circulate it4 ,the result was1 that the ,russian ,government stopped the issue4 ,the composition of this coin is--platinum1 #ig4j2 iridium1 #a4b2 rhodium1 #j4e2 palladium1 #j4be2 a little copper1 and a little iron4 ,it is1 in fact1 bad platinum3 it scales1 and it has an unfitness for commercial use and in the laboratory1 which the other well-purified platinum has not4 ,it wants working over again4 ,now1 ,deville's process depends upon three points1--upon intense heat1 blowpipe action1 and the volatility of certain metals4 ,we know that there are plenty of metals that are volatile2 but this1 ,i think1 is the first time that it has been proposed to use the volatility of certain metals--such as gold and palladium--for the purpose of driving them off and leaving something else behind4 ,he counts largely upon the volatility of metals which we have not been in the habit of considering volatile1 but which we have rather looked upon as fixed2 and ,i must endeavour to illustrate these three points by a few experiments4 ,perhaps ,i can best show you what is required in the process of heating platinum by using that source of heat which we have here1 and which seems to be almost illimitable--namely1 the voltaic battery2 for it is only in consequence of the heat that the voltaic battery affects the platinum4 ,by applying the two extremities of the battery to this piece of platinum-wire1 you will see what result we shall obtain4 ,you perceive that we can take about this heating agent wherever we like1 and deal with it as we please1 limiting it in any way4 ,i am obliged to deal carefully with it2 but even that circumstance will have an interest for you in watching the experiment4 ,contact is now made4 ,the electric current1 when compressed into thin conducting-wires offering resistance1 evolves heat to a large extent2 and this is the power by which we work4 ,you see the intense glow immediately imparted to the wire2 and if ,i applied the heat continuously1 the effect of the current would be to melt the wire4 ,as soon as the contact is broken1 the wire resumes its former appearance2 and now that we make contact again1 you perceive the glow as before4 ,the experiment was repeated several times in rapid succession4 ,you can see a line of light1 though you can scarcely perceive the wire2 and now that it has melted with the great heat1 if you examine it1 you will perceive that it is indeed a set of irregularities from end to end--a set of little spheres1 which are strung upon an axis of platinum running through it4 ,it is that wire which ,mr4 ,grove described as being produced at the moment when fusion of the whole mass is commencing4 ,in the same manner1 if ,i take a tolerably thick piece of platinum1 and subject it to the heat that can be produced by this battery1 you will see the brilliancy of the effect produced4 ,i shall put on a pair of spectacles for the experiment1 as there is an injurious effect of the voltaic spark upon the eyes1 if the action is continued2 and it is neither policy nor bravery to subject any organ to unnecessary danger2 and ,i want1 at all events1 to keep the full use of my eyes to the end of the lecture4 ,you now see the action of the heat upon the piece of platinum--heat so great as to break in pieces the plate on which the drops of metal fall4 ,you perceive1 then1 that we have sufficiently powerful sources of heat in nature to deal with platinum4 ,i have here an apparatus by which the same thing can be shewn4 ,here is a piece of platinum1 which is put into a crucible of carbon made at the end of one pole of the battery1 and you will see the brilliant light that will be produced4 ,there is our furnace1 and the platinum is rapidly getting heated2 and now you perceive that it is melted1 and throwing off little particles4 ,what a magnificent philosophical instrument this is4 ,when you look at the result1 which is lying upon the charcoal1 you will see a beautifully fused piece of platinum4 ,it is now a fiery globule1 with a surface so bright1 and smooth1 and reflecting1 that ,i cannot tell whether it is transparent1 or opaque1 or what4 ,this1 then1 will give you an idea of what has to be done by any process that pretends to deal with thirty1 or forty1 or fifty pounds of platinum at once4 ,let me now tell you briefly what ,deville proposes to do4 ,first of all1 he takes this ore1 with its impurities1 and mixes it 7as he finds it essential and best7 with its own weight of sulphuret of lead--lead combined with sulphur4 ,both the lead and the sulphur are wanted2 for the iron that is there present1 as you see by the table1 is one of the most annoying substances in the treatment that you can imagine1 because it is not volatile2 and while the iron remains adhering to the platinum1 the platinum will not flow readily4 ,it cannot be sent away by a high temperature--sent into the atmosphere so as to leave the platinum behind4 ,well1 then1 a hundred parts of ore and a hundred parts of sulphuret of lead1 with about fifty parts of metallic lead1 being all mingled together in a crucible1 the sulphur of the sulphuret takes the iron1 the copper1 and some of the other metals and impurities1 and combines with them to form a slag2 and as it goes on boiling and oxidising1 it carries off the iron1 and so a great cleansing takes place4 ,now1 you ought to know that these metals1 such as platinum1 iridium1 and palladium1 have a strong affinity for such metals as lead and tin1 and upon this a great deal depends4 ,very much depends upon the platinum throwing out its impurities of iron and so forth1 by being taken up with the lead present in it4 ,that you may have a notion of the great power that platinum has of combining with other metals1 ,i will refer you to a little of the chemist's experience--his bad experience4 ,he knows very well that if he takes a piece of platinum-foil1 and heats a piece of lead upon it1 or if he takes a piece of platinum-foil1 such as we have here1 and heats things upon it that have lead in them1 his platinum is destroyed4 ,i have here a piece of platinum1 and if ,i apply the heat of the spirit-lamp to it1 in consequence of the presence of this little piece of lead which ,i will place on it1 ,i shall make a hole in the metal4 ,the heat of the lamp itself would do no harm to the platinum1 nor would other chemical means2 but because there is a little lead present1 and there is an affinity between the two substances1 the bodies fuse together at once4 ,you see the hole ,i have made4 ,it is large enough to put your finger in1 though the platinum itself was1 as you saw1 almost infusible1 except by the voltaic battery4 ,for the purpose of shewing this fact in a more striking manner1 ,i have taken pieces of platinum-foil1 tinfoil1 and lead-foil1 and rolled them together2 and if ,i apply the blowpipe to them1 you will have1 in fact1 a repetition on a larger scale of the experiment you saw just now when the lead and platinum came together1 and one spoiled the other4 ,when the metals are laid one upon the other1 and folded together and heat applied1 you will not only see that the platinum runs to waste1 but that at the time when the platinum and lead are combined there is ignition produced--there is a power of sustaining combustion4 ,i have taken a large piece1 that you may see the phenomenon on a large scale4 ,you saw the ignition and the explosion which followed1 of which we have here the results--the consequence of the chemical affinity between the platinum and the metals combined with it1 which is the thing upon which ,deville founds his first result4 ,when he has melted these substances and stirred them well up1 and so obtained a complete mixture1 he throws in air upon the surface to burn off all the sulphur from the remaining sulphuret of lead2 and at last he gets an ingot of lead with platinum--much lead1 comparatively1 and little platinum4 ,he gets that in the crucible with a lot of scori and other things1 which he treats afterwards4 ,it is that platiniferous lead which we have to deal with in our future process4 ,now1 let me tell you what he does with it4 ,his first object is to get rid of the lead4 ,he has thrown out all the iron1 and a number of other things1 and he has got this kind of compound indicated in the table4 ,he may get it as high as #gh per cent4 of platinum1 and #bb of lead2 or #e1 or #aj1 or #ae of platinum1 and #ie1 or #ij1 or #he of lead 7which he calls weak platinum71 and he then places it in the kind of vessel that you see before you4 ,suppose we had the mixture here2 we should have to make it hot1 and then throw in air upon the surface4 ,the combustible metal--that is1 the lead--and the part that will oxidise1 are thoroughly oxidised2 the litharge would flow out in a fused state into a vessel placed to receive it1 and the platinum remains behind4 ,illustration3 ,fig4 #cf4 ,here is the process which ,deville adopts for the purpose of casting off the lead1 after he has got out the platinum from the ore4 7,having made use of your friend1 you get rid of him as quickly as you can47 ,he gets his heat by applying the combination of oxygen and hydrogen1 or of carburetted fuel1 for the purpose of producing a fire4 ,i have here a source of coal-gas2 there ,i have a source of hydrogen2 and here ,i have a source of oxygen4 ,i have here also one of the blowpipes used by ,deville in his process for working platinum in the way ,i have spoken of4 ,there are two pipes1 and one of them goes to the source of coal-gas1 and the other to the supply of oxygen4 ,illustration3 ,fig4 #cg4 ,by uniting these we obtain a flame of such a heat as to melt platinum4 ,you will1 perhaps1 hardly imagine what the heat is1 unless you have some proof of it2 but you will soon see that ,i have actually the power of melting platinum4 ,here is a piece of platinum-foil running like wax under the flame which ,i am bringing to bear against it4 ,the question1 however1 is whether we shall get heat enough to melt1 not this small quantity1 but large masses--many pounds of the metal4 ,having obtained heat like this1 the next consideration is what vessel is he to employ which could retain the platinum when so heated1 or bear the effects of the flame8 ,such vessels are happily well supplied at ,paris1 and are formed of a substance which surrounds ,paris2 it is a kind of chalk 7called1 ,i believe1 by geologists1 calcaire grossire71 and it has the property of enduring an extreme degree of heat4 ,i am now going to get the highest heat that we can obtain4 ,first1 ,i shew you the combustion of hydrogen by itself4 ,i have not a large supply1 because the coal-gas is sufficient for most of our purposes4 ,if ,i put a piece of lime obtained from this chalk into the gas1 you see we get a pretty hot flame1 which would burn one's fingers a good deal ,but now let me subject a piece of it to the joint action of oxygen and hydrogen4 ,i do this for the purpose of shewing you the value of lime as a material for the furnaces and chambers that are to contain the substances to be operated on1 and that are consequently to sustain the action of this extreme heat4 ,here we have the hydrogen and the oxygen1 which will give the most intense heat that can be obtained by chemical action2 and if ,i put a piece of lime into the flame1 we get what is called the lime-light4 ,now1 with all the beauty and intensity of action which you perceive1 there is no sensible deterioration of the lime except by the mechanical force of the current of gases rushing from the jet against the lime1 sweeping away such particles as are not strongly aggregated4 8,vapour of lime0 some call it2 and it may be so1 but there is no other change of the lime than that under the action of heat of this highly-exalted chemical condition1 though almost any other substance would melt at once4 ,then1 as to the way in which the heat is applied to the substance4 ,it is all very well for me to take a piece of antimony1 and fuse it in the flame of a blowpipe4 ,but if ,i tried this piece in the ordinary lamp flame1 ,i should do nothing2 if ,i tried a smaller piece1 ,i should do little or nothing2 and if ,i tried a still smaller piece1 ,i should do little or nothing2 yet ,i have a condition which will represent what ,deville carries to the highest possible extent1 and which we all carry to the highest extent1 in the use of the blowpipe4 ,suppose ,i take this piece of antimony3 ,i shall not be able to melt it in that flame of the candle by merely holding it there2 yet1 by taking pains1 we can even melt a piece of platinum there4 ,this is a preparation which ,i made for the purpose of proving the fusibility of platinum in a common candle4 ,there is a piece of wire1 drawn by that ingenious process of ,dr4 ,wollaston's1 not more than the three-thousandth part of an inch in diameter4 ,he put the wire into the middle of a cylinder of silver1 and drew both together until the whole compound was exceedingly thin2 and then he dissolved away the silver by nitric acid4 ,there was left in the centre a substance which ,i can scarcely see with an eye-glass1 but which ,i know is there1 and which ,i can make visible1 as you see1 by putting it into the candle1 where the heat makes it glow like a spark4 ,i have again and again tried this experiment up-stairs in my own room1 and have easily fused this platinum-wire by a common candle4 ,you see we have1 therefore1 heat enough in the candle1 as in the voltaic battery1 or in the highly-exalted combustion of the blowpipe1 but we do not supply a continuous source of heat4 ,in the very act of this becoming ignited1 the heat radiates so fast that you cannot accumulate enough to cause the fusion of the wire1 except under the most careful arrangement4 ,thus ,i cannot melt that piece of antimony by simply putting it into the candle2 but if ,i put it upon charcoal1 and drive the fiery current against it1 there will be heat enough to melt it4 ,the beauty of the blowpipe is1 that it sends hot air 7making hot air by the combustion of the flame7 against the thing to be heated4 ,i have only to hold the antimony in the course of that current1 and particle by particle of the current impinges upon the antimony1 and so we get it melted4 ,you now see it red-hot1 and ,i have no doubt it will continue to burn if ,i withdraw it from the flame and continue to force the air on it4 ,now1 you see it burning without any heat but that of its own combustion1 which ,i am keeping up by sending the air against it4 ,it would go out in a moment if ,i took away the current of air from it2 but there it is burning1 and the more air ,i give it1 by this or any other action1 the better it is4 ,so1 then1 we have here not merely a mighty source of heat1 but a means of driving the heat forcibly against substances4 ,let me shew you another experiment with a piece of iron4 ,it will serve two purposes--shewing you what the blowpipe does as a source of heat1 and what it does by sending that heat where it is wanted4 ,i have taken iron in contrast with silver or other metals1 that you may see the difference of action1 and so be more interested in the experiment4 ,here is our fuel1 the coal-gas2 and here our oxygen4 ,having thus my power of heat1 ,i apply it to the iron1 which1 as you see1 soon gets red-hot4 ,it is now flowing about like a globule of melted mercury4 ,but observe1 ,i cannot raise any vapour3 it is now covered with a coat of melted oxide1 and unless ,i have a great power in my blowpipe1 it is hardly possible to break through it4 ,now1 then1 you see these beautiful sparks3 you have not only a beautiful kind of combustion1 but you see the iron is being driven off1 not producing smoke1 but burning in a fixed condition4 ,how different this is from the action of some other metals--that piece of antimony1 for instance1 which we saw just now throwing off abundance of fumes4 ,we can1 of course1 burn away this iron by giving plenty of air to it2 but with the bodies which ,deville wants to expose to this intense heat he has not that means3 the gas itself must have power enough to drive off the slag which forms on the surface of the metal1 and power to impinge upon the platinum so as to get the full contact that he wants for the fusion to take place4 ,we see here1 then1 the means to which he resorts--oxygen1 and either coal-gas or water-gas#ai1 or pure hydrogen1 for producing heat1 and the blowpipe for the purpose of impelling the heated current upon the metals4 ,i have two or three rough drawings here1 representing the kind of furnaces which he employs4 ,they are larger1 however1 than the actual furnaces he uses4 ,even the furnace in which he carries on that most serious operation of fusing fifty pounds of platinum at once is not much more than half the size of the drawing4 ,it is made of a piece of lime below and a piece of lime above4 ,you see how beautifully lime sustains heat without altering in shape2 and you may have thought how beautifully it prevents the dissipation of the heat by its very bad conducting powers4 ,illustration3 ,fig4 #ch ,while the front part of the lime which you saw here was so highly ignited1 ,i could at any moment touch the back of it without feeling any annoyance from the heat ,so1 by having a chamber of lime of this sort1 he is able to get a vessel to contain these metals with scarcely any loss of heat4 ,he puts the blowpipes through these apertures1 and sends down these gases upon the metals1 which are gradually melted4 ,he then puts in more metal through a hole at the top4 ,the results of the combustion issue out of the aperture which you see represented4 ,if there be strips of platinum1 he pushes them through the mouth out of which the heated current is coming1 and there they get red-hot and white-hot before they get into the bath of platinum4 ,so he is able to fuse a large body of platinum in this manner4 ,when the platinum is melted1 he takes off the top and pours out from the bottom piece1 like a crucible1 and makes his cast4 ,this is the furnace by which he fuses his forty pounds or fifty pounds of platinum at once4 ,the metal is raised to a heat that no eye can bear4 ,there is no light and shadow1 no chiaro-oscuro there2 all is the same intensity of glow4 ,you look in1 and you cannot see where the metal or the lime is2 it is all as one4 ,we have1 therefore1 a platform with a handle1 which turns upon an axis1 that coincides with the gutter that is formed for the pouring of the metal2 and when all is known to be ready1 by means of dark glasses1 the workmen take off the top piece and lift up the handle1 and the mould being then placed in a proper position1 he knows that the issue of the metal will be exactly in the line of the axis4 ,no injury has ever happened from the use of this plan4 ,you know with what care it is necessary to carry such a vessel of mercury as we have here1 for fear of turning it over on one side or the other2 but if it be a vessel of melted platinum1 the very greatest care must be used1 because the substance is twice as heavy3 yet no injury has been done to any of the workmen in this operation4 ,i have said that ,deville depends upon intense heat for carrying off vapour2 and this brings me to the point of shewing how vapours are carried off4 ,here is a basin of mercury1 which boils easily1 as you know1 and gives us the opportunity of observing the facts and principles which are to guide us4 ,i have here two poles of the battery1 and if ,i bring them into contact with the mercury1 see what a development of vapour we have4 ,the mercury is flying off rapidly2 and ,i might1 if ,i pleased1 put all the company around me in a bath of mercury vapour4 ,and so1 if we take this piece of lead and treat it in the same way1 it will also give off vapour4 ,observe the fumes that rise from it2 and even if it was so far enclosed from the air that you could not form any litharge1 you would still have those abundant fumes flying off4 ,i may also take a piece of gold1 and shew you the same thing4 ,i have here a piece of gold which ,i put upon a clean surface of ,paris limestone4 ,applying the heat of the blowpipe to it1 you see how the heat drives off the vapour2 and if you notice at the end of the ,lecture1 you will observe on the stone a purple patch of condensed gold4 ,thus you see a proof of the volatilisation of gold4 ,it is the same with silver4 ,you will not be startled if ,i sometimes use one agent and sometimes another to illustrate a particular point4 ,the volatility of gold and silver is the same thing1 whether it be effected by the voltaic battery or by the blowpipe4 ,a lump of silver was placed in a charcoal crucible between the poles of a voltaic battery4 ,now1 look at the fumes of silver1 and observe the peculiar and beautiful green colour which they produce4 ,we shall now shew you this same process of boiling the silver1 cast on a screen from the electric lamp which you have before you2 and while ,dr4 ,tyndall is kindly getting the lamp ready for this purpose1 let me tell you that ,deville proposes to throw out in this way all these extraneous things that ,i have spoken of1 except two--namely1 iridium and rhodium4 ,it so happens1 as he says1 that iridium and rhodium do make the metal more capable of resisting the attacks of acids than platinum itself4 ,alloys are compounded up to #be per cent4 of rhodium and iridium1 by which the chemical inaction of the platinum is increased1 and also its malleability and other physical properties4 ,the image of the voltaic discharge through vapour of silver was now thrown upon the screen4 ,what you have now on the screen is an inverted image of what you saw when we heated the silver before4 ,the fine stream that you see around the silver is the discharge of the electric force that takes place1 giving you that glorious green light which you see in the ray2 and if ,dr4 ,tyndall will open the top of the lamp1 you will see the quantity of fumes that will come out of the aperture1 shewing you at once the volatility of silver4 ,i have now finished this imperfect account4 ,it is but an apology for not having brought the process itself before you4 ,i have done the best ,i could under the circumstances2 and ,i know your kindness well1 for if ,i were not aware that ,i might trust to it1 ,i would not appear here so often as ,i have done4 ,the gradual loss of memory and of my other faculties is making itself painfully evident to me1 and requires1 every time ,i appear before you1 the continued remembrance of your kindness to enable me to get through my task4 ,if ,i should happen to go on too long1 or should fail in doing what you might desire1 remember it is yourselves who are chargeable1 by wishing me to remain4 ,i have desired to retire1 as ,i think every man ought to do before his faculties become impaired2 but ,i must confess that the affection ,i have for this place1 and for those who frequent this place1 is such1 that ,i hardly know when the proper time has arrived4 ,,notes4 ,footnote #a3 ,page #af4 ,the ,royal ,george sunk at ,spithead on ,the #bith of ,august1 #aghb4 ,colonel ,pasley commenced operations for the removal of the wreck by the explosion of gunpowder1 in ,august1 #ahci4 ,the candle which ,professor ,faraday exhibited must therefore have been exposed to the action of salt water for upwards of fifty-seven years4 ,footnote #b3 ,page #ag4 ,the fat or tallow consists of a chemical combination of fatty acids with glycerine4 ,the lime unites with the palmitic1 oleic1 and stearic acids1 and separates the glycerine4 ,after washing1 the insoluble lime soap is decomposed with hot dilute sulphuric acid4 ,the melted fatty acids thus rise as an oil to the surface1 when they are decanted4 ,they are again washed and cast into thin plates1 which1 when cold1 are placed between layers of cocoa-nut matting1 and submitted to intense hydraulic pressure4 ,in this way the soft oleic acid is squeezed out1 whilst the hard palmitic and stearic acids remain4 ,these are further purified by pressure at a higher temperature1 and washing in warm dilute sulphuric acid1 when they are ready to be made into candles4 ,these acids are harder and whiter than the fats from which they were obtained1 whilst at the same time they are cleaner and more combustible4 ,footnote #c3 ,page #ai4 ,a little borax or phosphorus salt is sometimes added1 in order to make the ash fusible4 ,footnote #d3 ,page #bg4 ,capillary attraction or repulsion is the cause which determines the ascent or descent of a fluid in a capillary tube4 ,if a piece of thermometer tubing1 open at each end1 be plunged into water1 the latter will instantly rise in the tube considerably above its external level4 ,if1 on the other hand1 the tube be plunged into mercury1 a repulsion instead of attraction will be exhibited1 and the level of the mercury will be lower in the tube than it is outside4 ,footnote #e3 ,page #bi4 ,the late ,duke of ,sussex was1 we believe1 the first to shew that a prawn might be washed upon this principle4 ,if the tail1 after pulling off the fan part1 be placed in a tumbler of water1 and the head be allowed to hang over the outside1 the water will be sucked up the tail by capillary attraction1 and will continue to run out through the head until the water in the glass has sunk so low that the tail ceases to dip into it4 ,footnote #f3 ,page #cg4 ,the alcohol had chloride of copper dissolved in it3 this produces a beautiful green flame4 ,footnote #g3 ,page #ed4 ,lycopodium is a yellowish powder found in the fruit of the club moss 7,lycopodium clavatum74 ,it is used in fireworks4 ,footnote #h3 ,page #eh4 ,bunsen has calculated that the temperature of the oxyhydrogen blowpipe is #hjfa ,centigrade4 ,hydrogen burning in air has a temperature of #cbei ,c41 and coal-gas in air1 #bcej ,c4 ,footnote #i3 ,page #fj4 ,the following is the action of the sulphuric acid in inflaming the mixture of sulphuret of antimony and chlorate of potassa4 ,a portion of the latter is decomposed by the sulphuric acid into oxide of chlorine1 bisulphate of potassa1 and perchlorate of potassa4 ,the oxide of chlorine inflames the sulphuret of antimony1 which is a combustible body1 and the whole mass instantly bursts into flame4 ,footnote #aj3 ,page #fc4 ,the 8air-burner10 which is of such value in the laboratory1 owes its advantage to this principle4 ,it consists of a cylindrical metal chimney1 covered at the top with a piece of rather coarse iron-wire gauze4 ,this is supported over an argand burner1 in such a manner that the gas may mix in the chimney with an amount of air sufficient to burn the carbon and hydrogen simultaneously1 so that there may be no separation of carbon in the flame with consequent deposition of soot4 ,the flame1 being unable to pass through the wire gauze1 burns in a steady1 nearly invisible manner above4 ,footnote #aa3 ,page #gd4 ,water is in its densest state at a temperature of #ci4a ,fahrenheit ,footnote #ab3 ,page #gd4 ,a mixture of salt and pounded ice reduces the temperature from #cb ,f4 to zero--the ice at the same time becoming fluid4 ,footnote #ac3 ,page #hb4 ,potassium1 the metallic basis of potash1 was discovered by ,sir ,humphrey ,davy in #ahjg1 who succeeded in separating it from potash by means of a powerful voltaic battery4 ,its great affinity for oxygen causes it to decompose water with evolution of hydrogen1 which takes fire with the heat produced4 ,footnote #ad3 ,page #ih4 ,professor ,faraday has calculated that there is as much electricity required to decompose one grain of water as there is in a very powerful flash of lightning4 ,footnote #ae3 ,page #aja4 ,a solution of acetate of lead submitted to the action of the voltaic current1 yields lead at the negative pole1 and brown peroxide of lead at the positive pole4 ,a solution of nitrate of silver1 under the same circumstances1 yields silver at the negative pole1 and peroxide of silver at the positive pole4 ,footnote #af3 ,page #abi4 ,the gas which is thus employed as a test for the presence of oxygen1 is the binoxide of nitrogen1 or nitrous oxide4 ,it is a colourless gas1 which1 when brought in contact with oxygen1 unites with it1 forming hyponitric acid1 the red gas referred to4 ,footnote #ag3 ,page #aeb4 ,marble is a compound of carbonic acid and lime4 ,the muriatic acid being the stronger of the two1 takes the place of the carbonic acid1 which escapes as a gas1 the residue forming muriate of lime or chloride of calcium4 ,footnote #ah3 ,page #ahf4 ,lead pyrophorus is made by heating dry tartrate of lead in a glass tube 7closed at one end1 and drawn out to a fine point at the other7 until no more vapours are evolved4 ,the open end of the tube is then to be sealed before the blowpipe4 ,when the tube is broken and the contents shaken out into the air1 they burn with a red flash4 ,footnote #ai3 ,page #baf4 ,water-gas is formed by passing vapour of water over red-hot charcoal or coke4 ,it is a mixture of hydrogen and carbonic oxide2 each of which is an inflammable gas4 ,poster's note3 8combustion that makes60 was corrected from a misprint 8combusion that makes60 in the original4