CHEMICAL NEWS}

May 10,

I might add, that it always takes place if care is taken to mix with the liquid a very small quantity of one of those liquids in which spontaneous fermentation has been obtained.

Thus far there is nothing remarkable; it is a tartrate which ferments. The fact is known.

But apply this mode of fermentation to the paratartrate of ammonia, and, in the preceding conditions, it ferments. The same yeast, or leaven, is deposited. All indicates that things go on absolutely, as in the case of the right tartrate. If, however, we follow the steps of the operation with the aid of the polarising apparatus, we very soon perceive marked differences between the two operations. The liquid, at first inactive, possesses a rotary power sensibly to the left, which augments little by little and attains a maximum. Then the fermentation is suspended. There is no longer a trace of right acid in the liquid, which, evaporated and mixed with its volume of alcohol, immediately furnishes a fine crystallisation of left tartrate of ammonia.

We remark at first in this phenomenon two distinct things; as in every fermentation, properly so called, there is a substance which is chemically transformed, and correlatively, there is a development of a body possessing the manners of a mycodermic vegetable. Elsewhere, and it is this which it is important to note at this time, the yeast which causes the right salt to ferment, respects the left salt, in spite of the absolute identity of the physical and chemical properties of the two right and left tartrates of ammonia, whenever they are not subjected to dissymmetric actions.

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from one another in their refrangibility. But we noticed that this solar spectrum is not continuous, that it is intersected by dark lines which run through the whole length of the spectrum, and which occur always in sunlight. We noticed that these bands occur not only in direct sunlight, but also in reflected sunlight-in the light of the planets, and that these same bands do not occur in starlight. Hence Fraunhofer, as early as the year 1814, stated that these lines observed in the spectra of the sunand planet-light must in some way have their origin in the sun. We then proceeded to notice the properties of the light given off by artificially heated bodies. We saw that, with the exception of phosphorescence, light is given off only when a body becomes heated; and we divided artificial light as given off from heated substances into two great classes,-namely, that kind of light which is given off when a solid or a liquid is heated, and that kind of light which is given off when a gas is heated. We saw that when a solid or a liquid body becomes luminous it gives off light of every kind between certain limits-that its spectrum is continuous; whereas the light given off by a glowing gas is not of every kind-that such light produces a broken spectrum; and thus we learnt that it was possible to distinguish, by examining the light given off by such glowing gases, between the kinds of gas which were made to glow, but that we could not in the case of liquids or solids decide by the examination of the light what substance was heated; and thus we arrived at a knowledge of the possibility of founding the science of spectrum analysis-a science which will teach us what the chemical nature of a substance is by simply looking at the kind of light given off by its glowing vapour.

XIII. Such are, gentlemen, in their totality, the labours with which I have been charged to entertain

we inhabit.

We must remember that what we require to do in order to obtain such a knowledge of the constitution of terrestrial matter, is to obtain this terrestrial matter in the condition of a glowing gas. Now, we may divide, for the sake of illustration, the matter composing the globe into three classes,-that matter which is made gaseous and which becomes luminous near the temperature of the coal-gas flame; that matter, in the second place, which is volatile at a much lower temperature than that; and thirdly, that matter which is volatilised, and becomes luminous at a much higher temperature than that of the gas flame.

Thus, for instance, if I place a piece of clean platinum wire in this gas flame for a few moments, we shall observe that it does not impart any colour to the colourless flame. For a moment it does impart a colour, for a reason which I shall have to explain. The platinum itself does not give

A Course of Three Lectures on Spectrum Analysis, by Dr. H. E. Roscoe, Professor of Chemistry in Owens College, Manchester.

LECTURE II. (Saturday, April 5, 1862.) LADIES AND GENTLEMEN,-In our lecture last Saturday afternoon we investigated the properties of white solar light. We saw that the sunlight which produces upon our eye the impression of whiteness is, in reality, composed of an infinite number of different coloured lights; and we obtained, when we passed this white solar light through a triangular piece of glass, that which we called the solar spectrum-a broad band of variously coloured rays differing

temperature of the flame, and we do not get any platinum gas. But if I place another substance in this flame; for instance, a piece of common salt, we shall see that this flame is coloured of a peculiar tint, owing to the fact that the sodium is here volatilised, and that it becomes luminous, and gives off its peculiar and characteristic kind of light, namely, yellow. Now, by heating the platinum to a much higher temperature, we can get the peculiar light which it gives off. Thus, for instance, I have here a platinum pole, and by passing an intense electric spark through this, I obtain the platinum, as we shall see in a subsequent part of the lecture, in a state of luminous vapour, and then we find that the platinum also gives out the light which is peculiar and characteristic for platinum alone, and which no other body gives off.

That peculiar chemical substances produce in the flame peculiar colours has long been known, and this fact is used by the chemist as a means of detecting such substances. Thus, for instance, I will here show you a number of such differently coloured flames; here we can produce the luminous vapour of a number of these substances. I can here produce the characteristic yellow flame of sodium. If I bring the salts of potash into this flame I can produce the peculiar colour given by all those salts-a peculiar purple colour. Here I have the peculiar colour which is produced by a very interesting body with which we shall have to do in a subsequent part of the lecture-one of the new alkaline metals discovered by Bunsen, rubidium; and this is the flame coloured by the other new alkaline metal, cæsium, also discovered by Bunsen. Here we have lithium, which produces this magnificent red colour. Here we have the green produced by barium. All the salts of barium tint the flame of this beautiful green colour. Here we have the red produced by strontium. Here we have the orange produced by calcium, and here I will produce a peculiar blue flame by a substance which differs entirely from these in properties-the non-metallic element selenium. If I bring selenium into the flame, we shall see that this body imparts to the flame a very peculiar and beautiful blue colour. It is extremely volatile, and only lasts for a few seconds. Further on we have the peculiar blue colours communicated to the flame by copper and by boracic acid. I can show you the same thing in various ways. Here, for instance, I can produce a much larger flame, and show you the colour of the same salts. [A large gas flame was produced from a perforated jet of about three inches in diameter, and urged by a strong current of air. Pumicestone dipped in solutions of the chloride of sodium, potassium, barium, strontium, calcium, and lithium, were then held in the flame, the colours imparted by those substances being thereby again made evident.]

I will show you one more illustration of this with these papers. These are papers-gun-papers, in fact, which have been soaked in nitric acid, and which have then been steeped in solutions of these various salts. Here you see we shall have rather a quick combustion, but by reflection on the white screen the colour will be shown very well. [The lecturer then burnt gun- paper which had been dipped in solutions of the chlorates of the following substances: sodium, potassium, barium, and strontium.]

As I have said, it has been long known-that these various substances produce certain colours when brought into the flame. But if we now examine more closely what goes on when we have these variously-coloured flames burning before us, and what exact kind of light is given off; that is to say, if we examine the spectra of these differently-coloured flames, we find that we obtain very much more information concerning the matter than we do in this simple way by looking at the flames themselves. We look through a prism, or we employ Kirchhoff and Bunsen's more perfect arrangement, which you see here in the actual instrument before you, or here in the drawing; and we place a bead of the salt, the colour of whose light we wish to examine, in the flames here in front of this slit, as indicated in the drawing. I here bring a bead of chloride of barium into one of these flames placed at one side of the slit. The green light thus produced falls upon the small prism placed over the upper half of the slit, and it is thereby refracted so as to pass into the tube and through the large prism. Into the other flame, placed directly in front of the slit, I bring a bead of chloride of strontium, and the red light which this produces passes directly through the lower half of this slit on to the prism. In this way we obtain two spectra, one in the upper half of the field of the telescope, the other in the lower half; and we are thus enabled to compare very beautifully indeed the spectra which we wish to examine. Suppose, for instance, that we want to know whether a substance really is

barium; all we have to do is to place the substance which we know to be barium in the one flame, and to place the substance which we suppose to be barium in the other: if on looking through the telescope we find that these two sets of lines actually coincide-that the lines of the substances which we know to be barium coincide exactly with the lines of the substance which we suppose to be barium,-we then arrive at a very distinct knowledge that the substance is really what we suppose it to be. If we examine with such an instrument as this, which is the latest form of Bunsen and Kirchhoff's apparatus, such a flame as any of those we see burning before us, we observe what is represented very faithfully indeed by these painted diagrams. If we look at the yellow sodium flame, we notice that the sodium spectrum consists of one single bright yellow line, which, when we examine it more carefully with a larger number of prisms, we find is split up into two lines. Now, all the sodium compounds yield this peculiar spectrum; and nothing we know of, besides sodium and its compounds, will yield it. Potassium, which produced the purple flame we saw here, gives us a spectrum consisting of a portion of a continuous spectrum, with a bright line in the red and another in the violet. One of these lines is known as line alpha of potassium, and the other as the beta of potassium. These lines are not seen in any other substance, and they are seen in every potassium compound from which we can obtain this luminous vapour. Proceeding onwards, we find that we see the spectrum of lithium, consisting of one bright red and one orange line not so bright; and these three lower paintings-strontium, calcium, and barium-represent the spectra of those three alkaline earths. What we notice when we look at these flames through the telescope is exactly what is represented on that diagram.

Now, we may ask ourselves, "This is all very well, but what improvement is this method of analysis upon our ordinary chemical methods? What benefit is it to us that barium gives us these peculiar bands, that strontium yields certain different bands, that calcium produces others again? We know that the reactions of calcium, barium, and strontium are very different, and we can easily detect these substances by the ordinary chemical methods." The answer to this is, that this method is far more delicate than anything which has been hitherto used; that by means of this reaction we can detect such minute quantities that the delicacy of the method is almost past belief. I am sorry to say that I forgot to make an experiment with sodium to show you the delicacy of this process, because I am afraid that we have now so filled the room with that substance that we cannot get the reaction so delicately as I should like. I am afraid the flames will all burn now with the sodium reaction. I want to show you that dust contains sodium,-that we cannot take up a substance which does not contain sodium; and if I heat this platinum wire, we shall see that it contains sodium. The flame becomes distinctly yellow; and if I pass it between my fingers, you will see that my fingers contain sodium, and this you will see by the yellow colour imparted to the flame. I do not know now whether the dust from my coat will show the presence of sodium; it certainly would if the flame were not tinged by the sodium which is already in the atmosphere. I will try my coat. [The skirt of the lecturer's coat was dusted near the flame, and the presence of sodium in the coat-dust was rendered evidert.] This is not because it is the coat of a chemist; the dust from a book will show us the presence of sodium. You see that there is sodium in the dust of this book; in fact, every substance contains sodium, and therefore we can understand how Bunsen could recognise the 180 millionth part of a grain of sodium, for this was the small quantity that Bunsen and Kirchhoff found could be easily detected. But not only can we detect such minute traces of substances, but we thus gain important information respecting the distribution of bodies. In illustration of

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CHEMMAL NEWS, May 10, 1862.

this, I may mention that lithium-the body which gave us that magnificent red flame, and some of which we have here was only known to exist in a very few minerals; but Bunsen, on examining the spectra of various substances, saw that this red line, indicative of the presence of lithium, exists almost everywhere. He found it in the ashes of plants; and an experiment, which he is fond of showing, as illustrating the wide diffusion of lithium, is that of holding the end of the ash of a cigar in a colourless gas flame, and showing his friends the occurrence of the red lithium line, when the flame is observed by means of this instrument. We thus see that lithium is contained in the ashes of tobacco, in the ashes of many other land plants, in the oldest formations, in granite, and in the blood of animals. Instead of being, as was formerly supposed, a most sparingly-diffused substance, it is one which occurs almost everywhere; but owing to the small quantity of the substance present, it had been overlooked by our rougher and less exact methods of research. The crowning point of this investigation is, however, that of the discovery of two new alkaline metals by Bunsen. Bunsen, on examining the alkalies contained in the waters of Dürkheim, in Rhenish Bavaria (he had previously separated, by chemical means, all the other bodies from the water, and the substances which were left could only be alkaline substances), saw, on looking at the spectra produced by these, some lines which he had never seen in the spectra of any alkalies before; and he said, "There is a new alkaline metal contained here; this appearance must be produced by some new elementary body;" for no other substance which he knew of, or which he had examined, had ever given these lines before. Now, in a very interesting paper on these two new metals, which he calls rubidium and cæsium,-for reasons I shall explain to you presently, -Bunsen says that from 30 grammes of the mother liquor he obtained only 12 milligrammes of the impure salts of these two new alkaline metals. That was all he had to begin with,-about the one-hundredth part of a grain; but still, so sure was he of this method, and so certain was he that his spectrum never failed him, that he set to work at once and evaporated down 50 tons of this water to get some more of this substance. 44 tons yielded him only 105 grammes of the chloride of rubidium, and 70 grammes of the chloride of cæsium; so that out of 44 tons of water he got only about 200 grains of the mixed chlorides of these two new metals. Here I have a small specimen of the salts of cæsium, kindly sent to me by my friend Professor Bunsen. I have, however, more of the rubidium salts, which now can be obtained in larger quantities from the mineral lepidolite which I have mentioned. Bunsen, then, by the inspection of the spectra of these new alkaline metals determined their presence, and afterwards, having seen these lines, set to work to separate out the metals which caused them.

I will, with your permission, first show you the spectra of potassium and sodium, and afterwards the spectra of the new alkaline metals. Mr. Ladd will be kind enough to show us with the electric light these spectra; but you must not suppose, ladies and gentlemen, that what we get on the screen is exactly what we observe when we look through Bunsen's apparatus, which is adapted specially for analysis; but the results are extremely beautiful and interesting, and, I think, we shall see the distinguishing difference between the salts of rubidium and potassium. I will draw your attention, first of all, to the paintings representing the spectra which we are about to see. Rubidium and cæsium both possess spectra analogous to the spectrum of potassium. The difference in the spectra is but small. The potassium, as I have told you, gives a partially continuous spectrum; rubidium also gives a partially continuous spectrum; and the cæsium likewise gives a partially continuous spectrum; but at either end of all three spectra we find red lines in the least refrangible part, and violet lines in the most refrangible part; the two red rubidium

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lines are less refrangible than the potassium line, and these red lines [pointing to the diagram] do not exist in the eæsium spectrum. Bunsen has chosen two names for these two metals-casium from cesius, a greyish colour, and rubidium from rubidus, red, owing to lines of these colours being characteristic of the presence of these two metals.

Here we shall get the sodium spectrum; but I warn you that you will see other lines besides those given by sodium. The bright orange line is due to sodium. The sodium spectrum produces this bright orange line, which is alone seen here when we look at it through the more delicate instrument, and use a finer beam of light and a finer slit. We then see that the sodium spectrum consists solely of two bright yellow lines, which are separated by a very, very slight interval, and each of which is as fine as the finest spider's web. We cannot, unfortunately, exhibit the sodium lines in that way. There you see the splendid spectrum in which the orange band of sodium is very markedly visible. The other lines are not those which we have to attend to at present. It is impossible here, owing to the fact that our carbon points are impure, and contain certain metals mixed with the carbon, to get the pure spectra of the metals; and with this smaller apparatus, unfortunately, we cannot get light enough to throw the spectra on to the screen.

We now have the potassium spectrum, we still see the yellow band of sodium, because, as I have told you, sodium exists everywhere, and it is almost impossible to get the potassium pure; but we shall likewise see two other lines. There is the bright red band at one extreme end of the spectrum, and a violet one at the other end. These two are due to potassium. You notice also that the spectrum is continuous in the centre.

You

Now, we will take a mixture of potassium and sodium; such a mixture I have here. This mixture contains one part of sodium and twenty parts of potassium, yet the yellow colour of the sodium will cover entirely the purple colour of the potassium; and when we look at the flame with the naked eye we shall see nothing but the yellow flame, which might be produced by pure sodium. [A portion of the mixture was held in the gas flame, to which a bright yellow tint was communicated.] see this flame is as yellow as if it were pure sodium, yet it consists of one part only of sodium and twenty of potassium. But if we bring this mixture into the apparatus, and if we look at its spectrum, we find that the light of the sodium is kept to its own position. We have the bright yellow line of the sodium which does not interfere with the lines of the potassium, and these come out as distinctly as though no sodium were present at all. By allowing the bright sodium line to appear only where it ought, we see both the potassium lines coming out most beautifully.

Bunsen most eloquently describes, in his Memoir on this subject, the spectra which he sees when he places in the flame a mixture consisting of the chlorides of potassium, sodium, lithium, barium, strontium, and calcium, of each of which substances there is present only the one-thousandth part of a grain. He sees, first of all, the spectra of those substances which are most volatile appearing; the salts of sodium, potassium, and lithium are first seen; their spectra first come out, and these gradually fade away, and the spectra of calcium, strontium, and barium appear in all their vividness. Now, unfortunately, I cannot show you this with the beauty in which it is seen in the instrument when we allow the rays to fall on the retina; but you can see something which is very magnificent indeed. The mixture of all these chlorides together we now place in the carbon cup, and on bringing the upper carbon in contact with the mixture we shall volatilise the compounds, and we shall obtain the super-imposed spectra of all these substances. Mr. Ladd has now placed all the mixed chlorides in the cup, and on making contact we shall have all the

lines appearing. There you see what splendid bands we get now, and you will observe that some of the bands will gradually disappear, the light remaining constant; and others will appear with greater brilliancy, because the more volatile of these salts are driven off. There you notice the bright green bands of the barium. That splendid blue line is produced by strontium. Here we have the sodium; that is the green line of calcium; here we have the bright red line of lithium.

Now, how did Bunsen separate these new metals from one another, and from the old alkaline metals? I must give a moment to this point. In the first place, unless we could examine the spectra of cæsium and rubidium, we probably should never have discovered their existence at all. There is no doubt now that one at least of these newly-discovered substances has been handled by chemists before, but mistaken for potassium, in a certain mineral called lepidolite, which was known to contain lithium, and has now been found to contain a large quantity of rubidium. Rubidium and cæsium are so much like potassium in their chemical characters that, if it were not for this difference in the spectra, we should never have succeeded in separating one from the other, or in detecting any difference between these substances when they were present together. I can show you that rubidium and potassium are closely analogous. Here we take a solution of chloride of platinum. We know that it produces with potassium compounds an insoluble precipitate, and thus we distinguish these from the sodium compounds with which no such precipitate is produced. We shall at once get, as you will see, a quantity of this bright yellow precipitate of the double chloride of platinum and potassium.

Exactly the same thing we shall see will happen with rubidium. Here I have a solution of the chloride of rubidium. I add a few drops of this solution of chloride of platinum, and immediately we get a precipitate of the double chloride of platinum and rubidium. We cannot in the outward appearance see any difference between the precipitate formed by the rubidium and that formed by the potassium. This is one of the reactions by which we distinguish potassium from sodium, but you see we cannot in this way distinguish potassium from rubidium. We can make a similar experiment with tartaric acid. If we take some chloride of potassium and some chloride of rubidium, and add to each some tartaric acid, we shall obtain with both a white precipitate of the insoluble bitartrate.

But we can distinguish these new metals from potassium, and separate them by a difference of property which is exhibited by these platinum salts. We can distinguish them in this way: Here I have a solution in water of the double chloride of potassium and platinum. I will place some of this in both of these glasses. You will notice that when I add some of the chloride of potassium to this (the potassium bichloride of platinum) we obtain no further precipitate; it is impossible that we should thus obtain a precipitate; but if we add some chloride of rubidium to the potassium bichloride of platinum solution, we shall get at once a yellow precipitate showing that this double chloride of potassium and rubidium is much less soluble than that of potassium and platinum. This is the way in which Bunsen separatedrubidium and caesiumfrom potassium. Bunsen then investigated the salts; and we now have a Memoir, written by himself and Kirchhoff-the second Memoir on Spectrum Analysis-which contains a very elaborate and beautiful description of their researches on this subject. We are now acquainted with the nitrate, with the sulphate, with the carbonate, with the oxalate, with the hydrate, and even with the two new metals themselves; so that we have a chemical history of those two substances, which we must teach in future in all our classes. I must mention also that both rubidium and cæsium form salts which are isomorphous with the potassium salts; they crystallise in the same form, and they possess an analogous composition.

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Cæsium can be separated from rubidium by the solubility of the carbonate of the former metal in alcohol. The atomic weight of rubidium is 85.36, that of cæsium is 123:35.

We cannot see the end to which the application of this principle may lead. During the first few months it has led to the discovery of these two new metals, and we have not only their spectra examined, but also are acquainted with most of their salts. Another observation which shows us how rich is this field of inquiry, is, that a new elementary substance has probably been discovered by Mr. Crookes. He has not yet succeeded in preparing a large quantity of the body, and thus proving its chemical characteristics distinctly, but he has prepared a substanec which seems to differ in its chemical characters from all the other elements, and gives a totally different spectrum, consisting of one bright green line. Much is not known at present about this substance, but there seems very little doubt that it will turn out to be a new chemical element, to be added to the rather large family of elementary bodies. Now, although Bunsen and Kirchhoff are the real discoverers of this method, because they carried it out with all due scientific accuracy, and placed it on a sure foundation, yet we must not suppose, because they worked it out, the ground was, before them, absolutely untrodden. No great discovery is made all at once. There are always stepping-stones by which such a position is reached, and it is right to know what has been done previously, and to give such credit, as is their due, to the older observers. Now, the first notice we have of the property of these coloured flames was made by Thomas Melvill in the year 1752. He observed the yellow light given off by sodium vapour, but he did not know that it was due to soda, though he observed that a mono-chromatic light was given off. Sir David Brewster, in the year 1822, proposed a mono-chromatic lamp; but the original observation was due to Melvill. Herschel, in the year 1822, observed the spectra of several coloured flames, and in an article on Light in the Encyclopædia Metropolitana, in the year 1827, Herschel says, "The colours thus communicated by different bases to flame afford in many cases a ready and neat way of detecting extremely minute quantities of them." But it is to Fox Talbot, a gentleman well-known to us as one of the first investigators of the beautiful art of photography, that we owe the first valuable suggestions respecting this subject; and it is interesting to remember that Talbot made his experiments in the laboratory of this Institution, under the guidance of Mr. Faraday. Writing in the year 1826, he says: "The red fire of the theatres, examined in the same way, gave a most beautiful spectrum, with many light lines maxima of light. In the red these lines were more numerous, and crowded with dark spaces between,' [these are the strontium lines which you see on the diagrams there]-"besides an exterior ray greatly separated from the rest, and probably the effect of the nitre in the composition." [This really is due to the nitre.] "In the orange was one bright line, one in the yellow, three in the green, a very bright one in the blue, and several that were fainter." The blue line which he mentions was the blue strontium line which you saw, and concerning which I had hoped to speak, but I fear that I must defer that part of my subject. "The bright line in the yellow is caused, without doubt, by the combustion of sulphur." Talbot got wrong there, as did many other early observers. They did not suppose that so small a trace of sodium could produce that yellow light; and even Talbot says that no doubt the yellow line must be caused by the presence of water. He continues :-"If this opinion" (that is to say, the opinion about the formation of these lines) "should be correct, and applicable to the other definite rays, a glance at the prismatic spectrum of a flame might show it to contain substances which it would otherwise require a laborious chemical analysis to detect." That was written in

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CHEMICAL NEWS, May 10, 1862.

} March, 1826. In February, 1834, he writes:-"Lithia and strontia are two bodies characterised by the fine red tint which they communicate to the flame. The former of these is very rare, and I was indebted to my friend Mr. Faraday for the specimen which I subjected to prismatic analysis. Now, it is difficult to distinguish lithia red from the strontia red by the unassisted eye,' (as you have seen here, in fact,) "but the prism displays between them the most marked distinction that can be imagined. The strontia flame exhibits a great number of red rays well separated from each other by dark intervals, not to mention an orange and a very definite bright blue ray. The lithia exhibits one single red ray." Hence, I hesitate not to say" (says Talbot, writing in 1834) "that optical analysis can distinguish the minutest portions of these two substances from each other with as much certainty, if not more, than any other known method."

Sir David Brewster, in the year 1842, published some interesting observations concerning the spectra of coloured flames. Examining the coincidence of the bright metallic lines and the dark solar lines, he saw-and this is an important observation-that this bright red line in the potassium is a double line; and he noticed, in the year 1842, that this bright red line of potassium is coincident with, or has the same degree of refrangibility as the dark line A in the solar spectrum. Now, this was observed also quite lately by Kirchhoff, and entirely independently of Brewster, and they both agree that the dark line A is coincident with the red line caused by potassium. This has been lately denied by the French observer, M. Morren; but it seems to me that the researches of two such observers as Brewster and Kirchhoff, made independently of each other, and, especially, at a distance of eighteen years, must be correct.

Professor W. A. Miller, in the year 1845, took up the subject, and investigated the dark absorption bands produced by certain gases, and the bright lines in the spectra of coloured flames. Diagrams of these spectra accompany his Memoir, but they are not sufficiently characteristic to enable us to easily distinguish the particular metal, though in some cases they show lines which Bunsen's diagrams do not exhibit. In his observations he did not refer to the application of these researches for the purpose of detecting the metals producing these bright lines. Here I have some representations of Dr. Miller's lines. This is the barium spectrum; this is the calcium spectrum; and this is the strontium spectrum, as drawn by him in the year 1845. You see they differ from those of Bunsen and Kirchhoff, because Dr. Miller had a continuous spectrum at the same time. His flame was not a nonluminous one, as was the case with the one used by Bunsen and Kirchhoff.

Ladies and gentlemen, I have already taken up the allotted time. I am sorry to say I had a great deal more to say, which I must defer to the next lecture. I may add that I shall be happy to exhibit to those who stay, the spectra of the new metals by means of the electric lamp. [After the lecture Mr. Ladd exhibited the spectra of rubidium and cæsium. In the rubidium spectrum were seen two bright violet bands, as well as the two characteristic red lines in the ultra-red portion of the spectrum. The violet lines of the caesium were also seen, and noticed to be less refrangible than those of the rubidium.]

Annual Meeting, Thursday, May 1, 1862. The DUKE OF NORTHUMBERLAND, F.R.S., President, in the Chair.

THE Annual Report of the Committee of Visitors for the year 1861 was read and adopted. The amount of contributions of members and subscribers in 1861 amounted to 30137. 108., the receipts for subscriptions to lectures were 740%. 11s. 6d.; the total income for the year amounted to

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46937. 98. On December 31, 1861, the funded property was 28,655. 178. 2d.; and the balance at the bankers, 9687. 16s. 8d., with six Exchequer bills of 100l. each. A list of books presented accompanies the Report, amounting in number to 524 volumes; making, with those purchased by the managers and patrons, a total of 524 volumes (including periodicals) added to the library in the year. Sixty-three lectures and twenty-one evening discourses were delivered during the year 1861.

Thanks were voted to the President, Treasurer, and Secretary, to the Committees of Managers and Visitors, and to Professor Faraday, for their services to the Institution during the past year.

The following gentlemen were unanimously elected as Officers for the ensuing year :

President-The Duke of Northumberland, K.G., F.R.S. Treasurer-William Pole, Esq., M.A., F.R.S. SecretaryHenry Bence Jones, M.A., M.D., F.R.S. Managers-The Rev. John Barlow, M.A., F.R. S.; William Bowman, Esq., F.R.S.; Sir Benjamin Collins Brodie, Bart., D.C.L., F.R.S.; Warren De la Rue, Esq., Ph.D., F.R.S.; George Dodd, Esq., F.S.A.; The Earl of Ducie, F.R.S.; John Hall Gladstone, Esq., Ph.D., F.R.S.; William Robert Grove, Esq., M.A., Q C., F.R.S.; Sir Henry Holland, Bart. M.D., D.C.L., F.R.S.; The Lord Lovaine, M.P.; William Frederick Pollock, Esq., M.A.; Lewis Powell, M.D., F.S.A.; Robert P. Roupell, Esq., M.A., Q.C.; Lieut. Gen. Edward Sabine, R.A., Pres. of Royal Society; Colonel Philip James Yorke, F.R.S. VisitorsNeill Arnott, M.D., F.R.S.; Hon. and Rev. Samuel Best; George J. Bosanquet, Esq.; Archibald Boyd, Esq.; Bernard Edward Brodhurst, Esq.; John Charles Burgoyne, Esq.; George Frederick Chambers, Esq.; Hon. Sir Charles Crompton, Justice of Queen's Bench; Edward Enfield, Esq.; Captain Frederick Gaussen; the Duke of Manchester; John MacDonnell, Esq.; Colonel William Pinney, M.P.; George Stodart, Esq.; Hon. Sir James P. Wilde, Baron of the Exchequer.

CHEMICAL SOCIETY.

Thursday, May 1, 1862.

Dr. A. W. HOFMANN, F.R.S., President, in the Chair. DR. T. ANDERSON gave a discourse "On the Chemistry of Opium." Since the year 1803, opium had attracted the attention of chemists; of late years the principal point aimed at had been the preparation of morphine in a pure state. In extracting the opium in order to obtain the bases it was better to use only a small quantity of water heated to about 150° F., in which case all the narcotine would be dissolved out, and only woody fibre left; but if a large quantity of water were used, the narcotine was left behind in the insoluble residue. The alkaloids existed in combination with a peculiar organic acid called meconic acid, and another acid had been discovered in opium which was isomeric with lactic acid. The liquid obtained by extraction with water was mixed with a certain quantity of chloride of calcium, and the precipitated meconate of lime separated, after which the solution was concentrated and allowed to stand, when hydrochlorate of morphine and hydrochlorate of codeine crystallised out; these bases could be easily separated by precipitation by ammonia, the codeine being soluble in water. It was generally supposed that the codeine formed a double salt with ammonia, but from Dr. Anderson's experiments this did not appear to be the case. The mother-liquor from which the hydrochlorates had been deposited gave, on the addition of ammonia, a precipitate containing narcotine, papaverine, thebaine, and codeine, together with numerous resinous matters; the presence of the last-mentioned base in the precipitate was remarkable on account of its solubility in water. On di