Imatges de pàgina
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face of the glass and arrived at the lower surface, it particle of ice to the particle of air, there is a little reflecdoes not all escape through to the air, some is reflected tion, that the snow becomes an opaque body; and if you back again, although the greater portion is refracted observe snow after it has fallen, upon the mountains of through the surface below. Now, wherever you have Switzerland, and has had the air squeezed out of it by the refraction you always have reflection. There is, therefore, enormous pressure of the superincumbent mass, you will reflection at the bottom surface as well as the top, and find it is actually converted from white snow into beautiful thus you have two beams reflected instead of one. In pure, transparent ice. To make an experiment to illustrate fact, supposing this to be the outline of our plate of glass, this, I will take first a piece of bibulous paper. This

paper was once a pulp or jelly, as you know, and was partially transparent, because the fibres of the paper were then mixed up with water, and in passing from the fibre to the water there was not much light lost. These fibres are little transparent threads, and in the case of this paper they are separated from each other by little interstices filled with air; in passing from one fibre to the air, and from the air to the next fibre, there is reflection of light ; and this occurs so often that the paper is converted into an opaque substance. If, instead of having air between the fibres of the paper, I throw between them a liquid which has almost the same power of refraction as the fibres themselves, then I destroy this reflection, in virtue

of which it is rendered white, and I think you will see and supposing a ray of light (a b) to fall upon it thus, | when I make use of such a liquid that I powerfully it is bent as you know towards the perpendicular, and on | augment the transparency of this paper. That simple leaving the glass it is bent again from the perpendicular experiment when you dip your towel in the basin in the thus (6 c, c d), but here (at b) there is a portion of light morning, is extremely full of philosophy; the towel reflected, and here (at c) there is also light reflected. becomes darker because the interstices are filled with Another portion is reflected and refracted here also (at e), water instead of air, and becomes more transparent. I and thus you get a series of reflections from the two have here some of the bibulous paper. Mr. Anderson internal surfaces of this piece of glass. When the will give me a little olive-oil, a substance possessing piece of glass is thick you see the difference between those pretty nearly the same refractive power as the fibres rays more strikingly than when it is thin. Take a looking of the paper. I will dip a rod of glass into the glass, and look very obliquely in it at a white object, you oil, and cause a drop of it to fall upon the do not see one image merely. If you place a candle near paper. First of all I cast the inage of the white paper the surface of that looking glass and look at it in the glass upon the screen. Having done that, I will show you you see a series of images. First of all, you have a how I at once augment the transparency of the paper tolerably bright image, then a very bright image, then if I allow a drop of oil to fall upon it. There is the oil the rest get dimmer and dimmer till they actually become trickling down, and you see how greatly the transparency 100 dim to be seen. The first image you see, which is is augmented by the saturation, the filling up of the little rather bright, is the one reflected from the first surface of interstices of the paper with the oil, which possesses a the glass, the second, which is extremely bright, is from refractive index very nearly equal to that of the fibres of the silvered surface behind, and then you get a series of the paper itself. Thus you see in this way we can render reflections from side to side. I have here such a piece of this opaque substance in some measure transparent : and glass, and will make the experiment with the help of this is the philosophy of the tracing paper used by my lamp, and will show you these images obtained at the engineers ; they take tissue paper, saturate it with oil, forward and the backward surface of the looking glass. dry it, and then place it upon their drawings; then they If I cause a beam of light to strike obliquely upon this can easily see through it, and copy the plan underneath glass you see first of all an image reflected from the upon the tracing paper. These things have all their anterior surface, and then you see further on another peculiar philosophy. very bright one reflected from the silver surface, and next Let me now go on to the more immediate subject of this you have a series of images becoming gradually fainter day's lecture. I have said at the commencement of the and fainter until they are invisible.

list of memoranda that when a ray of light passes from a Now, I want to turn for a moment to another matter of rarer medium to a denser it is bent towards the perpensome importance. I have said, that wherever you have dicular. You must not, however, imagine that the heavier refraction you have reflection, and if you have no refrac- the body the more power it has to bend a ray of light. tion you have no reflection. Take a liquid and a solid ; That is in a great many instances the case, but not always, no matter how different the solid may be in substance from as I will prove to you. For instance, I have here a cell, the liquid, no matter how much heavier, if it only bends a and this cell contains two substances perfectly transparent, ray of light to the same degree as the liquid, it acts just one floating above the other. The under liquid is water, the same as the liquid itself, and becomes invisible when the top is turpentine. The spirit of turpentine you see is it is plunged into it, owing to the absence of refraction lighter than the water, and is therefore less dense. It and reflection at the two bounding surfaces. I have said floats upon the water ; but still you will find that it will in the memoranda that if you plunge the eyeball of an bend the ray more than the water, notwithstanding its ox into water, it vanishes; it appears like the water, being less dense. We will make our experiment in the although it is a totally different substance.

usual way. I will project its image on the screen, and When light passes from one medium to another of a you will see very clearly the limiting surface between the different refrangibility, there is always reflection. And turpentine and the water. There is a little undulation of thus, if you mix two transparent bodies together, baving the surface caused by the motion, and you see our beaudifferent powers of refraction, the reflection may occur so tiful beam divided by a thin dark line which corresponds often as to render this mixture perfectly opaque. Thus to a portion of light reflected by that surface. The beam foam--which is only water-is as white as snow; and if I is at present going straight through; but I will turn my take snow itself, its particl:s are perfectly transparent, cell so as to cause the beam to fall ubliquely upon both but it is because the particles of ice have air mixed up liquids (and remember, the image is inverted, the turpenwith them,-because when the light passes from every tine, which is really at the top, appears at the bottom; the

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eell being apparently turned upside down, as I have a little triangular glass prism, polished on the sides and faee. already explained to you), when, if the turpentine, the Suppose a ray of light were to strike straight against the lighter liquid of the two, possesses a greater power of refraction than the water, its image will move the most. When I move the cell obliquely you see that the line of continuity is immediately broken, and it is perfectly manifest that the lower image is moved further than the other, and if I turn it in the other direction you will have the same result, thus proving that the turpentine has a greater power of refraction than the water, although it is less dense. Hence, when we speak of one body being denser than another in optics it will not do to affix the ordinary surface (c) in the direction (a b), then it so happens that idea to the term dense. What is meant by a dense body in the case of glass it meets it so obliquely that it is totally in optics is one which retracts the light powerfully; and reflected downwards or upwards, as the case may be. Í when one body refracts more than another it is the denser | think I cannot do better than show you the total reflection of the two.

of the image of the coal points, which you know so well Let me pass on to another very important portion of our already. There you see that beautiful image, and I will subject, and that is the subject of total reflection. This let the ray strike right plumb against the face of the prism; is very important, and is capable of being understood by it goes through and is reflected from the other, so that you all of you. I will suppose this to be a vessel containing will see the image of the coal points upon the ceiling. I water, this (a b) being the surface of the liquid. We know will now send the ray of light in another way through the

prism, parallel to the long surface; when it enters the
prism it is refracted through the first surface, and strikes
against the hypothenuse ; it is there again totally reflected
(see Fig.), and will quit the surface exactly at the same
angle at which it entered. This is also a case of total
reflection; when I turn the prism, you have the coal points
turning round horizontally, one, as it were, attacking the

I will now direct your attention to another very interesting case of total reflection, a case which I intend to illustrate if I can by means of this apparatus. I have on this stool ar electric lamp, and in front of it is a hollow

| iron vessel connected by a pipe with the water-pipes of the Ś F C

building, so that I can allow the water to enter it, and issue that if a beam of light fall upon the surface obliquely, it forth in the form of a jet from a hole near the top of the is bent down on entering. We also know that, supposing vessel. At the back, opposite the hole from which the we had a luminous point (at c) underneath the surface, at vein of water will issue, there is a plate of glass, and I the bottom of the vessel, and a ray of light quitted that can send, as you will see immediately, a beam of light luminous point along this line (c d), it would on emerging from the electric lamp through this plate of glass and from the water be bent in this way (d ). Suppose straight through this vessel : I think you will see a cone a second ray of light starts from the bottom of the vessel of light passing through the hole and falling upon the part in this direction (f'd), it will be refracted on quitting the of the audience in front. I will now have the vessel water, thus (df). Supposing now I draw a third ray filled with water, and when the jet issues, the beams of (gd) starting from this point (9), a ray of light coming | light that you saw striking against the audience will along that line (g d) would be bent so that it would just strike obliquely against the interior surface of that vein of cross the surface and emerge along the line (d g). Now water. What is the consequence? They cannot get out supposing you come to a point beyond that ray (gd), of the vein, they will actually be washed down as if the which, when refracted, just crossed the surface, and sup: light was a solid thing, and reflected from side to side, but posing a ray of light were to come up from that point (1) so obliquely that they cannot quit the liquid ; and I trust to this (d). What would becoine of that ray ? Tois oné in that way to illuminate the vein of water from top to (gd) we suppose has just crossed the surface; this one, bottom, by carrying down the light which formerly passed then (h d), will not be able to get out of the medium at all, straight through. If I interpose a coloured glass the vein but will be totally reflected or thrown back along the line of water will be coloured. [The lecturer interposcd glass (dh); we have passed the limit of refraction, and got into of different colours, thereby colouring the vein of water.] the limit of what is called total reflection; the ray is So much then for this beautiful effect of the total reflection wholly driven back into the medium again, and cannot of light within the vein. escape from it. I find it so in this very turpentine; I look You have seen that by the most simple arrangement upon it and find that when a ray of light falls obliquely of lenses we have obtained very beautiful effects; we have from the turpentine into the water, the light falling upon obtained images of medals and of these coal points by one the surface is totally reflected, and communicates to it simple lens. You know also that with a convex pair of a shining metallic lustre. This is an experiment you can spectacles we can obtain inverted images of candles or any make for yourselves. Take a little water in a common other object sufficiently luminous to cast a reflection on glass tumbler of this kind, put a spoon in, and look at the the screen I am now about to show you one or two effects spoon from beneath through the side of the glass ; it is with an apparatus which is a little more complicated than evident that the rays of light from the spoon strike against the simple lens I have hitherto used. The apparatus I the upper surface of the water and cannot get out, so that have in my hand depends upon the same principle as, but is you have a beautiful image of the spoon above. Put a much more refined than, the magic lantern. The magic shilling in the glass underneath the water, look from below lantern consists simply of two parts, one part to illumi. at the surface, and you have a second splendid bright nate the object, and the other part to make a magnified burnished shilling apparently floating upon the water | image of that object on the screen. I have here the above"; because the rays of light, not being able to get oui, representation of a little boy who is brushing a boot. are reflected back again and strike your eye, and thus you First of all I illuminate that boy by casting a beam of have it floating upon the surface of the water. I have here light on this glass transparency. The light goes through


Royal Institution of Great Britain.


Jan. 25, 1862.

it, and then by means of this lens that you see here, I cast night is equally beautiful. There they are ; how they an image of the boy on to the screen. The lamp does rush like living things through the liquid! This then is nothing more than illuminate the thing. Thus I have one of the things that this beautiful microscope is capable to all intents and purposes a magic-lantern. There of showing. is the little fellow you see. We are not here merely I will now-go on to the consideration of another portion for the purpose of looking at those ridiculous of our subject, and that is the most wonderful optical inthings, but for the purpose of knowing the principle strument of all the human eye. You will understand on which all these things, ridiculous and un-ridicu. the general structure of the eye in a moment. Cast your lous, depend. Here also we have a microscope eye upon any one of those figures here (referring to Figures formed by the combination of lenses. I can throw a powerful 1, 2, and 3.] light upon the object that I put between these two slides, and thus illuminate it very powerfully. Here in front, you see, I have a little system of lenses, by means of which I shall get a very high magnifying power, and I trust to be able to show you objects which would entirely escape your power of sight if I made use of a lens of the former kind. Every boy present must have seen those figures that are not at all uncommon now in London and elsewhere-those beautiful figures of the frost-those beautiful crystals that are frequently formed upon the surface of the window panes. I am sure those things are worthy of every boy's attention, and not only worthy of boys' attention, but worthy of men's also, for they are among the most wonderful things in the world. We hear people talking contemptuously of matter, and pouring scorn upon matter ; but these are only people who do not understand matter. Matter, like everything else in creation, is glorious when you see its laws and phenomena with a clear eye. Now, these little particles of water have a power inherent in themselves of building themselves up in geometric forms when they are chilled when they are cold : they have the power of building themselves up in these wonderful and beautiful crystals that you see upon the surface of the window panes. I have sometimes warmed a pane of glass on which those crystals were deposited, and I have produced thereby a You have there the general structure of the eye, supposing liquid film all over the pane, and I have looked on that it to be cut through, and that you look at the cut film, and I have seen it just begin to inove, and then the sideways.

| sideways.

There is

There is a thing just in front of the eye little atoms have run together as if they were alive, and like a watch glass, called the cornea; it holds a little have weaved a web of such beauty, that nothing man ever fluid called the aqueous humour and behind that there did, or can do, can approach it, and still this is very is a little lump of jelly-like matter called the cryscommon. It is a thing occurring every winter, and I do talline lens ; and it would really be worth while to not know whether boys have ever sufficiently reflected

get an ox's eye from a butcher and cut off the coat and upon the marvellous beauty-upon the wonderful miracle get at this liitle lens. Behind is the general mass of the that is involved in the formation of these splendid frost

eye-ball, filled with what we call the vitreous humour. As crystals. There is not a bit of sugar-candy which you I look at the audience, what takes place? Something that suck which does not involve questions before which Sir

ought to excite your wonder and astonishment. When I Isaac Newton, Mr. Faraday, or the wisest man who ever look towards you, if any of you could get behind and look lived, is a mere child-he absolutely knows nothing about at the back of my eye you would see printed upon a little it; and yet we continue thoughtlessly to pass over these space at the back of my eye an image of the whole beauties without opening the eyes of our minds to their audience, some perfectly distinct, others not so distinct. wonderful history. I will try now to show you a similar Those that I look at distinctly are perfectly imaged. case by freezing some other substance-not water, for I Now, there is another remarkable thing that instead of cannot readily freeze water with a strong beam of electric sitting upright, you are depicted in my eye sitting with light upon it, but I will take some other substance that I

your heads downward. Supposing that (No. 3) to be an can freeze, or at least, try to freeze. In the first place it is

arrow, the rays of light go through the pupil of the eye, absolutely essential for this experiment that I should have through this round hole that you see in the centre, which my plates of glass perfectly clean ; and so I do not wash is surrounded by what is called the iris. The light comes them simply with water but first with strong solution of from the pupil thus, and the point of the arrow sends its potash. Mr. Anderson will now give me a solution of light upwards, and the feather end sends its light downsal-ammoniac ; and this is the thing that I am going to wards; so that you see the image of the arrow is inverted freeze-or rather 10 crystallize :-freezing is a process of on the retina, as it is called,-an extension of the optic crystallization, but you would not perhaps apply the term nerve at the back of the eye. freezing to this action. I have now a film of liquid upon I want to actually prove to you, by experiment, that this glass plate, somewhat similar to that of water upon that is the case,-a very rude experiment, indeed, but still the window pane, and I will try and introduce the plate a very instructive one. I have here tried to make an eye; between those two slits and illuminate it by means of the it is a very large spherical glass vessel filled with water. electric light and cast the image on to the screen. [The You see I have surrounded it on one side with black experiment was then performed and in a few seconds the paper. There is a hole in the paper which represents the crystals of sal-ammoniac were seen shooting into the field pupil of the eye. I will place in front of that hole a of view.] There you see it, boys; look at those crystals crystalline lens and will allow the light to fall upon the which are being formed, do they not march like an army; lens and through the water. Here at the back there is a the “atoms march in tune," as some poet says. The tracing paper screen sufficiently transparent to allow you process that goes on upon the window panes on a winter's to see an object through it. This tracing paper represents

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the retina. We will see if we cannot get an inverted image remains upon the eye during the time the point goes of the candle upon the retina. (A lighted candle was round-that is, if it go round as quickly as I have said. placed in front of the artificial eye.] There is the candle, If it travel round the circle in less than the fifth of a and you see the image of the candle is inserted on the second, you find that it forms a continuous line. Now, retina ; we will throw a beam of light upon the candle so instead of a burnt stick, I will take our lamp and I will as to illuminate the stem of the candle, and then, I think, try to show you this line of light on the ceiling. I will we shall see it still brighter, [This was accordingly done, reflect this beam of light--this fine index you have there You see how finely shown it is: the candle is pretty visible from a looking-glass, and if I am skilful enough in turning from this point behind the tracing paper, and is inverted. this, you see the light travel round and gives a single Now, let me take something else ; let the assistant go in image. If it travel quickly enough you see a continuous front and I will illuminate his hands. There, you see the ring of light, because every revolution is accomplished image, and if he puts his hand upright you will see that within the time that the image takes to subside; and thus, the image of the finger-nails will be down. In like manner as I have stated in the list of memoranda, when a series of if I take the dial of my watch you see I can throw its sparks follow each other in succession at intervals of less image on the retina, and a very beautiful object it forms. than the fifth of a second, the impression made by one

We have to bear in mind, first of all, that in order that spark remains upon the eye until that made by the next an object may be seen with distinctness, the rays of light spark, and you see the succession of sparks as a continuous issuing from it must come exactly to a focus upon the line. Here I haye a beautiful case of this kind, which retina. Now, what takes place really? Some boys' eyes will show it to you very distinctly. Here is a system of very often have too powerful a refraction; they combine tubes, and we have a little battery underneath the table, the rays of light here (No. 1) [indicating a spot between by meane of which I can send an electrical discharge the crystalline lens and the retina] ; and the consequence through them. [The experiment was then performed.] is they cause the rays of light to come to a focus before Here we have this beautiful effect; you see in each of these they reach the retina, and thus, instead of having a branches we have a continuous light. There is a series of sharp point upon the retina, you have a hlurred image discharges, and each single image corresponds to a single as you saw there, when I did not hold the watch at discharge. If I turn it at a certain amount of speed, you the proper distance. Some eyes, especially old eyes, have see that the wheel appears to be resolved into distinct not the power of converging the rays of light sufficiently, spokes. Here you see [causing the branches of the and what is the consequence? They do not come to a apparatus to revolve rapidly) I have a star of light. This focus at all; the eye is unable to bring them to a focus on is owing to the continuity of the impression produced by the retina; they converge towards a point behind the the succession of these discharges. retina. This is a case of long sight. What does the boy do who is short sighted ? He holds the object close to the eye, because he wants to throw the point of intersection

Special General Meeting. back. He has to look closely at the object, and hence he

Monday, January 13, 1862. is said to be “short sighted;" and such boys, if they ao not wish to look at the thing very closely, have to put a

The Rev. John Barlow, M.A., F.R.S., Vice-President,

in the Chair. concave lens in front of the eye: this gives the rays a certain amount of divergence, and the focus is thrown

The following Address to Her Majesty, the Queen, in back to the retina. On the contrary, those people who reference to the decease of H.R.H the Prince Consort, wish to bring this point of intersection forward must use a Vice-Patron of the Royal Institution, on December 14th convex lens, as I have said. The eye has insufficient last, was read and unanimously adopted : power to refract the rays. To help the refraction we place a double convex lens, or a plano-convex lens in front. I will show you these different lenses. Sometimes when I TO THE Queen's Most EXCELLENT MAJESTY. am tired I 'require to look through a pair of spectacles, and Mr. Anderson has given me the spectacles that he

1. May it please your Majesty,–We, the Members uses in this room, and here is another pair of spectacles of the Royal Institution of Great Britain, respectthat he uses for reading, or when he wants to see small

fully desire to express to your Majesty our grief objects. Now, I will show you the difference between these

for the loss which has fallen upon the Kingdom, different glasses. I will take my own spectacles first, Here I want to show you, first of all, the convergence of

upon our Institution, and, with exceeding weight, the beam of light into the middle of the lens ; but look upon your Majesty personally. how far I have to go away in order to get a perfectly clear May it please God, who grants consolation in image of the coal points. They are quite small; but perfectly clear. Now I will take Mr. Anderson's least

His own due time, to give it to your Majesty, magnifying spectacles—those with which he looks at you, eren while your thoughts are directed towards and there you see the image is very large-larger than him that is gone, and may the recollections of mine. If I take this other pair of Mr. Anderson's

our Prince's doings whilst in life have an abiding --those which he uses to read by-you see for yourselves how large the image is. Many of you, I have no doubt,

influence for good upon the many millions who have fathers who use spectacles of this kind ; borrow have heard of and rejoiced in his name. them and make this beautiful experiment for yourselves.

I will now say a few words on the effect of the impression made upon the eye. When a flash of light falls upon the eye, supposing that flash of light could pass away instantly it strikes the eye, does the impression vanish

CHEMICAL SOCIETY. at the moment the light vanishes ? No. "Everything in nature takes time to subside ; and the consequence is that if you take the burning end of a stick, and then cause it to

Thursday, January 16, 1862. pass slowly through the air, you can follow the point of! A Paper, by Dr. H. BENCE JONES, On the that stick ; but if you make it describe a circle in about Variations of Hippuric and Uric Acids in Hea the fifth of a second, you see that circle as a continuous Urine," was read by the Secretary. line of light, because in point of fact the impression The determinations of the amount of hij

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SCHEMICAL NEWS, 52 Chemical Society.

Jan. 25, 1862. present in urine that had been made both by Dr. A. Wise-centratel, sulphate of lead is deposited. With nitric acid man and by M. Ravenshoe, gave very high results ; the the following quantities were dissolved :method employed by M. Ravenshoe being that recommended by Profesor Liebig, two healthy men being the subjects

Result of Evanoration.

OF Weight of Salt. experimented upon ; the amount of hippuric acid in the

1'079 0'329925 urine obtained from patients suffering from

1 Octohedral crystals of nitrate of different 1'123

5755000 diseases had also been determined, but Dr. Bence Jones


lead. thought that further experiments on its occurrence during

A crystalline powder of nitrate

0.009725 disease were needed. A table was exhibited showing the amounts of uric and

| When the salt was digested with nitric acid containing hippuric acids occurring in samples of urine obtained from

sixty per cent. of acid, it was almost entirely converted various subjects both before and after food had been taken,

into octohedra of nitrate of lead, but the whole of the control determinations having been made in each case ;

sulphate was not decomposed even on standing for several Liebig's method being employed.

days. Dr. MARCET remarked, that he had tried to extract

Dr. GLADSTONB remarked that it was a curious circumhippuric acid from urine by means of ether, but that other

stance that diluting a solution of sulphate of lead in acids and urea were partially taken up by the solvent, and

hydrochloric acid, chloride of lead was deposited, and he also the colouring matter of the urine ;. it was, however,

thought a redistribution of the acids and base took place. easier to obtain it from other parts of the system, as for

He had examined solutions of phosphates, oxalates, and instance from the blood ; he had found the following other salts, and found that no precipitate was produced on process to answer in this case :- After coagulating the

dilution; he had observed that if to a solution of sulphate blood by heat, filter, and concentrate, then add alcohol,

of lead in hydrochloric acid either sulphuric acid or a lead filter, again concentrate, add dilute sulphuric acid to

salt were added, sulphate of lead was deposited. separate fat, neutralise with chalk, evaporate to dryness, Mr. FIELD said that sulphate of lead was completely deand extract the hippurate of lime by means of alcohol.

composed either by oxalic or hydrochloric acid. He also stated that the presence of this acid in diseased

Mr. De la Rue remarked that sulphuric acid will not urine had been detected by several experimenters.

separate lead completely even from a solution of the acetate, Mr. Bloxam said he had employed several published and that more remained in solution than was due to the methods for the extraction of hippuric acid, but had not solubility of the sulphate in water. found them to succeed satisfactorily.

The next Paper was by Dr. Hugo MULLER,“ On a Nera The PRESIDENT said that Dr. Bence Jones had employed Mode of Effecting Chlorine Substitutions." He had found Liebig's process, which was to evaporate the urine and that a great difference existed between the action of add hydrochloric acid, and then to act on the precipitate chlorine alone on organic compounds, and its action on obtained with ether, so that the urea did not interlere ; | the same compounds in the presence of iodine ; also, that that the concordance between the control determinations in the latter case the action took place with much greater was a proof of their correctness, and that he himself was facility. Benzol, for instance, although acted upon with assistant to Liebig when he was making experiments difficulty by chlorine alone, was attacked with ease by the upon this method of determining the acid, so that he could mixture of the two elements; two series of compounds speak from experience as to its correctness.

being obtained, the formulæ of which are expressed as The next Paper was by G. F. RODWELL, Esq. “ On the

follows: Solubility of Sulphate of Lead in Hydrochloric and Nitric

# H, C12

#H, CI Acids." In order to determine the solubility of the salt

GH, cii

@ H, CI,

CH, Cla in acids of different strengths, pure and dry sulphate of

€ H, Cig lead was digested in the acid at the ordinary temperature

From these tables it will be seen that when chlorine alone for a period of from one to ten days; the maximum

was employed, direct union took place, but with chlorine amount was, however, always dissolved before the fifth

and iodine together substitution products were obtained. day. To determine the amount dissolved, a portion of

Burmese naphtha had also been experimented vpon and the solution was weighed out, a little sulphuric acid

furnished several compounds. With bisulphide of carbon, added, and the whole evaporated to dryness, ignited, and

chloride of sulphur and chloride of carbon were obtained, weighed. It was impossible to evaporate in the ordinary

and a third body, which was probably a compound of way a concentrated solution of the sulphate in hydro

carbon, chlorine, and sulphur. When chlorine was passed chloric acid, for a scum was apt to form on the surface,

into a solution of iodine in acetic acid in the cold, no and this was thrown out by the expansion of the steam

action took place ; but on the application of heat chlorunderneath ; this difficulty was overcome by evaporating

acetic acid was produced even in the dark, although when the solution in a crucible, and finishing the process in an

chlorine alone is employed strong sunlight is known to be air bath, the lid being placed on the crucible. The fol

necessary. It was possible that the iodine acted as a lowing determinations have been made :-A hundred grains

carrier of the chlorine, or that the action might be similar to of hydrochloric acid dissolved the following weights of

that of pentachloride of antimony, or of phosphorus. the salt:

The PRESIDENT remarked that the ordinary process for obtaining substitution compounds was sometimes very

tedious, and that a process which would render their preSpace Of Weight of Salt.

Result of Dilution.

paration easier would be very valuable. 10515 O'14665 | No precipitate.

Mr. DE LA RUE said that the present results were merely J'oso

the beginning of a series which Dr. Müller and himself Needle-shaped crystals deposited. 0:35495 1.107 0.946525 A larger quantity deposited.

hoped shortly to lay before the Society. 1135 2.113800 Ditto.

The PRESIDENT inquired how rapidly the action of 2-854000 1'157

chloroform upon glacial acetic acid took place, to which Ditto.

Dr. MULLER replied that it acted with great rapidity,

the limit of production depending merely on the size of If the solution be evaporated, plates of chloride of lead the apparatus. are deposited, which, when dissolved in water and re- ! Mr. Bloxam inquired whether phosgene gas could be crystallised, furnish needles; but if the solution of the produced in this manner; but it appeared that this experisalt be evaporated until the suiphuric acid becomes con- ment had not yet been tried.

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