THE minutes of the previous meeting having been read, Messrs. Walter Odling and C. W. Vincent were formally admitted Fellows of the Society. The donations to the Society were then announced by the Secretary, and the following names read for the first time-Messrs. Charles L. Field, Walter T. Goolden, B.A., B. W. Richardson, F.R.S., Donato Tommasi, Edgar Beckit Truman, Thomas H. Davies, William Masters, A. Campbell Dixon, James Baynes, Thomas Jamieson, Robert Williamson, Charles James Hislop Warden, Francis Jones, Sydney Knowles Muspratt, Felix M. Rimmingtons, Edward Cleminshaw, Samuel Herbert Cox, and Arthur B. Kitchener. For the third time-Messrs. Edward Collens, George Bult Francis, William Edward Porter, John Turner, and William Charles Young, who were ballotted for and duly elected. Dr. ODLING said it was not customary for the President to address the Fellows at the first meeting of the session, but he could not help saying a few words of welcome and congratulation on their taking possession of their new rooms, and they might regard the assistance they had received from the State, unaccompanied as it was by State control, as some recognition of the advantages of scientific research to the national welfare, and as tending to the mental and moral cultivation of the people. It was necessary for them to have some place of meeting, and it would be impossible for them to provide such handsome rooms as they had now, indeed to provide rooms at all would be a very serious inroad on their funds. He might mention two new features-one the commodious store-room for the spare numbers of their journal, and the other the laboratory adjoining the meeting-room, the primary use of which would be for giving experimental illustrations in connection with the papers brought before the Society. After alluding to the various benefits to be derived from their meeting together, the speaker said that chemical science treated of things that could be handled, and phenomena which could be observed, and the use of the laboratory was offered to those who brought new facts before the sciety to illustrate those facts, for we all know the great dght and interest chemists take in witnessing such experients. With regard to the financial aspect of the matter, they had incurred considerable expense, although the Government had given the gas-fittings and the new book-shelves in the library; however, all that was useful in the old rooms had been removed here, and utilised in one way or other; even the old historic seats, which were formerly those of the Royal Society, formed part of the benches in that room. He could not but tell the Fellows that it was owing to the great exertions of the Junior Secretary, Dr. Russell, that they were enabled to remove to their new rooms in time for this meeting, and throughout the arrangements they had met with the greatest courtesy and kindness both from Mr. Barry, the architect, and also from the Clerk of the Works. The first paper, "On the Optical Properties of some Modifications of the Cinchona Alkaloids," by D. HOWARD, was read by the author. After enumerating the various observations that had been already made on this subject, he drew attention to the approximate relation between the deviation caused by quinicin and cinchonicin and the alkaloids from which they are derived; thus the mean of the specific rotary power of quinine and quinidin in alcoholic solution is 47° to the right, and that of quinicin, corrected for its combined water, 41°, whilst, in aqueous sulphuric acid, they are 20'5° and 19.4° respectively. A similar approximation is found to be the case with cinchonicin as compared with cinchonin and cinchonidin. The action of nascent hydrogen on the alkaloids in acid solution gives rise to compounds which Schützenberger regards as differing from the original compound in containing atom more water; the author, however, is inclined to doubt this, as no evolution of hydrogen occurs when cinchonin or cinchonidin is treated with zinc and dilute sulphuric acid until a considerable excess of the acid has been added: the optical properties of the bodies formed are very similar to those of quinicin and cinchonicin. The author then proceeded to describe the method of preparation and optical properties of the various ethyl bases produced by the action of ethyl iodide or bromide on the cinchona alkaloids: the rotation produced by the salts of the ethyl bases is in most cases very nearly proportional to that which would be given by a salt of the original alkaloid, equal in amount to that contained in the new compound. The PRESIDENT thanked the author in the name of the Society for his interesting memoir, and hoped he would take advantage of his great opportunities, and give the Society some further results of his experiments. Dr. FRANKLAND had listened with much interest to Mr. Howard's account of the alteration produced on the polarised ray by the effect of combination. It was a matter of great importance to accumulate results on this subject, so as to endeavour to ascertain what circular polarisation means, chemically speaking. The alteration in the intensity is not only produced by combining two substances of opposite rotary powers, but sometimes also by the combination of a rotary body with a neutral one. observed amongst the cinchona alkaloids an instance in which combination with an indifferent body had caused a reversal of the rotation of the polarised ray. He would like to ask the author whether he had ever Dr. WRIGHT suggested to the author that he should determine the heat of combustion of some of these isomerides, to see whether there was any relation between the heat evolved and the rotary power, somewhat similar to that which had been observed in many volatile bodies between the heat of combustion, and the boiling-point. Mr. HOWARD replied that he had not found any instance in which inversion of the rotary power took place where the altered compound could be re-converted into the original substance. In dealing with bodies of so complex a nature and so delicate a structure, which were so very easily destroyed, the difficulty was to find cases where they give satisfactory results at all. Dr. C. R. A. WRIGHT then read a "Preliminary Notice on the Oils of Wormwood and Citronella." The portion of oil of wormwood boiling between 195° and 200°, and termed by Gladstone absinthol, C10H160, when treated with phosphorus pentasulphide, is decomposed, a hydrocarbon being produced which boils at 170° to 180°, and a yellowish oil boiling at 230° and upwards. The hydrocarbon, after purification, boiled at about 176°, and, on analysis, appeared to be cymen, produced in the reaction C10H160 H2O+C10H14. The yellowish liquid boils at about 235°, and is chiefly thio-cymen or cymyl-sulphydrate, identical with that recently obtained by Fliesch from camphor. Oil of citronella, when distilled, yields an unstable body of the formula CroH180, which unites with bromine, and the product, chloride is left behind; this is again chlorinated, and C10H18Br2O, when heated, splits up thusagain sublimed, until the whole is transformed into the trichloride. C10H18Br2O H2O+2HBr+C10H14. The resulting cymen is apparently identical with that already known. The PRESIDENT, after expressing thanks for Mr. Hannay's paper, adjourned the meeting until Thursday, the 20th of November. ROYAL INSTITUTION OF GREAT BRITAIN. GEORGE BUSK, F.R.S., Treasurer in the Chair. The PRESIDENT, having thanked the author for his communication, called on Mr. W. F. DONKIN to read his paper "On the Estimation of Nitrates in Potable Waters," This process is founded on the reaction that a nitrate in the presence of chlorides, when treated with phenol and sulphuric acid, gives a reddish solution, which, on the addition of an excess of ammonia, changes to a more or less decided blue; this gradually becomes more intense on standing. The water under examination is compared with a standard solution of potassium nitrate containing a known quantity of the salt; these are treated in a precisely similar manner. The process is capable of accuThe special thanks of the members were given to rately determining the amount of nitrates present to Charles Woodward, F.R.S., for his present of his work on within part in 4,000,000 of water; it is, however, the "Polarisation of Light," and of much valuable necessary to closely observe certain details given in the apparatus illustrating the subject; and also to William paper, in order to insure this result, slight variations in Salmon, M.R.I. for his donation of ten pounds for the the manner of conducting the operations or in the quanti-promotion of scientific research in the Royal Institution. ties of the reagents employed producing corresponding The presents received since the last meeting were laid variations in the depth of tint obtained. on the table, and the thanks of the members returned for the same. Dr. ODLING said the determination of the amount of nitrates in water was a subject of interest to many of the Fellows present, and if an easy process for determining ammonia could be devised, it would be a boon to water analysts all over the country. Dr. FRANKLAND remarked that, although much attention had been devoted to the determination of nitrates and In Henry Adolphus Focking, and Major John Andover Wood were elected Members of the Royal Institution. MANCHESTER LITERARY AND PHILOSOPHICAL SOCIETY. Ordinary Meeting, October 7th, 1873. Chair. MR. SAMUEL BROUGHTON was elected Treasurer of the nitrites in waters, there was still room for another process. E. W. BINNEY, F.R.S., F.GS., Vice-President, in the The aluminium process answered admirably with a water which gave a large residue with comparatively little organic matter, and the mercury and sulphuric acid process when much nitrate was present, but it was not trustworthy when the amount of the latter was very small. those cases where there was a large residue and a large amount of organic matter, he hoped the new process might prove available, but he thought the accuracy of the method had not been pushed far enough. The mercury process fails when the amount present in the water is less than o'01 in 100,000. He would like to ask the author whether he had made any experiments on such minute quantities. Mr. W. THORP congratulated Mr. Donkin on obtaining such good results with a colour process, the difference detected being about 1 per cent on the total quantity, whilst with the Nessler test it required a practised eye to detect a difference of 21 per cent. He thought, when the amount of nitrates was but small, that the mercury and sulphuric process was rendered thoroughly satisfactory by adding a known quantity of a standard solution of a nitrate to the water previous to evaporation, the object being to obtain a measurable quantity of gas, thus overcoming the difficulties which were merely mechanical. It is recorded in the Proceedings of this Society that a letter dated from Southport, and written by Dr. Joule, was read at the meeting held on the 5th October, 1869. In that letter it is remarked that "Mr. Baxendell noticed the fact that at the moment of the departure of the sun below the horizon the last glimpse coloured bluishgreen." Dr. Joule also observes that on two or three question, and that "just at the upper edge where bands occasions he had himself noticed the phenomenon in of the sun's disc are separated one after the other by refraction, each band becomes coloured blue just before it vanishes." During the past eighteen months the writer, from his residence in Blackpool, has had frequent opportunities of observing the setting sun, and has noticed the phenomenon of the final coloured ray certainly more than fifty times. To the naked eye its appearance has generally been that Mr. DONKIN, in answer to Dr. Frankland, said he had not made further experiments on very small quantities of similar to one of the effects seen when the sun shines of a green spark of large size and great intensity, very nitrates he had examined a water containing a large upon a well-cut diamond. The colour, however, is by no amount of residue, which yielded a faint blue tint, but had not tested for nitrates by any other process. One of means constant, being often, as in the case of Mr. Baxthe great advantages of the method was its rapidity; half-endell's observation, bluish-green, and at times is mentioned by Dr. Joule, quite blue. The period of its a-dozen determinations could easily be made in a morning. The Secretary then read a "Note on the Action of Iodine duration, too, is likewise variable. Sometimes it lasts Trichloride upon Carbon Disulphide," by Mr. J. B. HANNAY. but half a second, ordinarily perhaps a second and a The author finds that the result of the action of pure quarter, and occasionally as much as two seconds and a half. carbon disulphide on iodine trichloride is represented by the equation 4CS2+6IC13=2CICC14+2CSC12+3S2Cl2+3I, and suggests that the different results obtained by Weber were probably owing to the iodine trichloride he employed containing monochloride. The author prepares the pure trichloride by passing chlorine over iodine in a retort, with occasional agitation, until a reddish yellow solid is produced. Heat is then applied, and a yellow sublimate of the trichloride is formed in the receiver, whilst mono When examined with the assistance of a telescope, it becomes evident that the green ray results at a certain stage of the solar obscuration, for it begins at the points or cusps of the visible segment of the sun, and when the "setting" is nearly complete extends from both cusps to the central space between, where it produces the momentary and intense spark of coloured light visible to the unaided eye. From the fact of the green cusps being rounded I apprehend that irradiation contributes to the apparent NEWS magnitude of what is seen. The range of colour, too, as seen in the telescope, is more varied, and the duration of the whole phenomenon more extended, than when the observation is made only with the naked eye. Of the objective nature of the phenomenon it is needless to offer evidence; for it needs to be but seldom seen to preclude the idea of an optical illusion. That the waters of the ocean have nothing to do with the production of the colour is made manifest by its visibility when the sun "sets "behind the edge of a well-defined cloud. On the 14th and 15th of June, for instance, it was seen at upper contact of the solar limb with clouds. On the earlier date in question a thin band of cloud stretched across the setting sun, and under a power of fifteen diameters the green effect was seen at upper contact with the cloud, and again at final disappearance below the horizon. On the later date it was again seen at upper contact with each of several filaments of cloud, and again at final disappearance. And on several other occasions the writer has observed the effect when the disappearance of the sun has taken place at an elevation of six or eight degrees behind a heavy bank of clouds. Respecting the increased range of colours seen when the phenomenon is observed with telescopic aid, I may mention that on the 28th of June the sea was calm and the sky quite cloudless at the setting of the sun. Of the final coloured rays fifteen diameters showed the first to be a full and splendid yellow, which was speedily followed by the usual green, and then, for a second and a half, by a full and perfect blue. Respecting the increased duration of the colour, I have found that when the atmosphere is sufficiently favourable to allow a power of sixty diameters being employed, with a 3-inch object-glass, the green effect is seen at that part of the sun's limb in contact with the horizon, even when one-half the sun is still unset, and of course from then till final disappearance. The different colours seen, together with the order of their appearance, are suggestive of the prismatic action of the atmosphere as the cause of their production, and the interception of the horizon or the cloud as the cause of their separation. Assuming the correctness of this view, it becomes evident that an artificial horizon would prove equally efficacious in separating the coloured bands, and also that if employed during an inspection of the sun's lower limb the least refrangible end of the spectrum would be disclosed. Accordingly I introduced into an eyepiece of my telescope a blackened disc of metallic copper, having a slit cut in it of about the one hundred and fiftieth of an inch in width, and proceeded to make an observation, in July, when the sun was about one-half of its meridian height. The blinding glare, however, of that portion of the sun seen through the slit rendered the observation futile. By projecting a large image of the sun into a darkened room, I was enabled to get the whole of the spectrum produced by the prismatic action of the atmosphere in a very satisfactory manner. In this case a semicircular diaphragm was used, so placed that its straight edge divided the field of view into equal parts, from one of which it obscured the light. The diaphragm was placed as before in the focus of the eyepiece, and by rotating it every portion of the sun's limb could be in turn examined, and that too in the centre of the field, so as to be equally subjected to the minimum of the peculiarities of the instrument. When the sun's lower limb was allowed to descend into the field of view the first rays were intensely red. After a momentary duration they gave place in succession to orange, yellow, and green, which were then lost in the ordinary refulgence of the The upper linib gave green, blue, and finally purple, which latter colour I have thus far never seen upon the natural horizon. It should be remarked that the colours seen were vivid and unmistakable, and each one of them easily detained at will, or the whole phenomenon recalled, by the adjusting screws of the instrument. I apprehend that the results here given sufficiently prove that at mo sun. spheric refraction is the cause of the coloured rays seen at the moment of the sun's departure below the horizon. I have, however, thought it worth while to examine the light proceeding from the moon's limb by the aid of the artificial horizon, and of course by direct observation. The results were decisive and satisfactory, the spectral colours being easily observed. The green effect I have also frequently seen on the departure of the moon beneath the edge of a dark and well-defined bank of clouds. Telescopic aid has, however, in every instance been required. The rapid changes in colour observable in the case of almost any large fixed star at an elevation of twenty or thirty degrees above the horizon, and which changes vary between red, green, and blue, may I think be fairly attributed to the same cause as the colour in the sun's final ray. Particles of dust floating in the air act, I apprehend, for the moment, in the capacity of diaphragm or horizon, and thus enable the eye to perceive, even in the light of the stars, the prismatic action of our atmosphere. Ordinary Meeting, October 21st, 1873. EDWARD SCHUNCK, Ph.D., F.R.S., F.C.S., Vice-President, in the Chair. W. BOYD DAWKINS, F.R.S, exhibited a fragment of a post struck by lightning, on 2nd June, 1873. It formed one of three, about 8 feet high and 15 feet apart, in the garden of II, Norma Road, Rusholme, and stood under a cherry tree, of which the stem was 10 feet away. It was completely shattered, fragments being driven as far as the walls of the house, 25 yards off, and the downward direction of the loose splinters implied that the explosive force was exerted from below upwards, instead of from above downwards. People in the Dickenson Road observed what they termed a "thunderbolt" fall, as they thought, on the house, and some of the inhabitants describe it as a flame of light followed immediately by a crash of thunder. It is very probable that the explosion was produced by an electric current passing from the earth upwards, and not vice versa. Professor REYNOLDS attributed the shattering of the post to the explosive or repulsive action of an electrical discharge of unusual intensity. Mr. BAXENDELL thought it was most probably due to the sudden conversion of a portion of the moisture in the post into steam of high tension by the heating action of the electrical discharge, and mentioned instances in which condensed vapour was said to have been seen rising from trees immediately after they had been struck by lightning. "On the Relative Work spent in Friction in giving Rotation to Shot from Guns Rifled with an Increasing and a Uniform Twist," by OSBORNE REYNOLDS, M.A., Professor of Engineering, Owens College, Manchester, and Fellow of Queens' College, Cambridge. The object of this paper is to show that the friction between the studs and the grooves necessary to give rotation to the shot consumes more work with an increasing than with a uniform twist; and that in the case of grooves which develop into parabolas, such as those used in the Woolwich guns, the waste from this cause is double what it would be if the twist was uniform. This is important, for, although the magnitude of this waste does not appear as yet to have been the subject of direct inquiry, it will be seen that with the plane grooves it amounts to more than I per cent of the whole energy of the shot, and, consequently, with the parabolic grooves it will amount to 2 per cent of the energy of the shot; that is, to say the least, important as regards the effect of the discharge; and when we consider that all the work spent in friction is spent in destroying the gun and the shot, we see that it becomes a matter of the very greatest importance whether the gun spends 1 or 2 per cent of its power on selfdestruction. MR. BAXENDELL read the following extract from a letter he had received from the President :-" You will see that I have put a little drying apparatus to the short-limb on my syphon barometer. I believe that a long open tube attached to the short end by a bit of india-rubber tube will do just as well. This I am going to try, and also to exclude the air more perfectly than I find it is in the instrument at the Rooms. The principal fear was that the sulphuric acid would slowly act on the mercury. I think the barometer has been put up long enough to decide this, and I feel convinced that the plan will succeed. NOTICES OF BOOKS. Chemistianity (Popular Knowledge of Chemistry); a Poem: also an Oratorical Verse on each known Chemical Element in the Universe, giving Description, Properties, Sources, Preparation, and Chief Uses, arranged for Familiar or Memory Reading. By J. CARRINGTON SELLARS, F.C.S. Published by the Author (at his Office), Ferry Buildings, Birkenhead. THIS is, without exception, the most remarkable book of the season. Its title-water-marked on every leaf,-its style, its terminology, its probable design, must alike puzzle the unfortunate critic, who in addition, finds himself defied in such passages as the following: "Waste-paper set-trap writers shall daunt me not; As freezing water from Muscovy duck." In place of the " Muscovy duck," we fear that a more familiar bird may possibly be suggested to the mind of the reader. The work consists of a "prooemium," treating of a promiscuous assemblage of topics; a "prologue"; a description of the elements in oratorical verse, forming the main body of the book; and an appendix, containing a proposal for an entirely new system of chemical nomenclature. Novel terminology is, indeed, the author's forte. Thus, where chemists would speak of "chemical action" or "reaction," the Chemistian uses the word "goception," derived, as he kindly informs us, "from 'gang,' to pass, and 'præcipio,' to command." Then we have "floral" and "effloral" used as synonymes, respectively, for "mineral" and "organic." Copper is described as the "siamatic bond metal." Last, but not least, we instance "chemistianity" itself. Let us pause, however, before censuring the author for the use of such terms. If he has sinned, he is not alone. He may plead the example of men who, unable or unwilling to enrich science with new facts, new methods, or new generalisations, have earned fame, influence, and professorial chairs by the easier process of translating old doctrines into the terminology of the hour. If paradoxes and neologisms form the royal road to scientific eminence, it would be unfair to shut it against Mr. Sellars. In the "prooemium" the author exclaims :- Themselves would write in some approved system, Then there would be less obscurity And more learning, yielding hornpipe joys through Earth." Let us make few selections to show the author's approved system : "Therefore a human being may be said to be on certain subjects-simple, knowledgeful, subearth-willed, highwitted or with godly lore endowed. One division of the condition of a moleculed being might (diffidently) be imagined as that of clarified godly lore." Here is a portion of a Chemistian song:- So hee, so ho, so heigh. Miss Basic Merit's foe, NEWS Trade-fraud, we'll plunge in woe, And urge Commercial Honesty, So heigh, so hee, so ho." We were not aware that Merit was "Basic" rather than acid, and that it, or rather she, was a young lady. Elsewhere we read : "One toned word, like an old familiar tune, Will suffice to cant-er a rhyming coon." When gocepted under Wheeler Blowdome." From these and similar specimens, which might be greatly multiplied, we are forced to own that, however valuable the truths which the author seeks to convey, his mode of expression is not the most felicitous. It would be interesting to put this volume into the hands of some intelligent person totally unacquainted with chemistry, and to observe what notion of the science he would obtain from its perusal. The "Oratorical Verse" contains little which is not correct in fact; still it would be difficult to find any information here which is not given more clearly and intelligibly in works easy of access. Hence we fail to see the raison d'etre of the volume before us. Profit, we are bound to admit, cannot have been the author's motive for appearing in print. He may, possibly, be suffering from the effects of a certain book of which we have heard it said that, when the chemical student has done with it, he may hand it over to his sister or his sweetheart as a collection of crochet patterns. Mr. Sellars concludes his work with a proposal for a system of "alphabetical composition names for the chemical elements and "their mineral (floral) compounds." Hydrogen, for instance, is to be called "abgen," to be pronounced abb; water becomes DiAbBe; boracic acid is TriAbAmtriBe; chloride of barium is diEbKe. Surely this proposal will commend itself to a certain section of the "Chemistian" world! MISCELLANEOUS. Iron in Tea.-Mr. Alfred Bird, of Worcester Street, sends a letter to the Birmingham Daily Post on this subject. He says "In your report of yesterday's proceedings at the Police Court you make me say that the magnetic oxide was natural to tea.' What I said was 'that the magnetic oxide of iron exists naturally in the soil in which the tea plant grows,' in proof of which I stated that I had separated from the magnetic oxide of iron (found in the tea) particles of mica and quartz, the inference being that, as magnetic oxide of iron forms part of the soil of China, it would rise with the dust of the country, and, coming in contact with the damp leaves, would adhere to them when they are dried, and thus make the dried tea leaves stick to the magnet as if there were iron-filings mixed up amongst them.' I also stated that, not having any of the actual soil of China to examine for magnetic oxide of iron, it occurred to me to try if the dried leaves of plants grown in this country would be attracted by the magnet. Accordingly, I dried 100 grains of French bean leaves, grown in my own garden in the Bristol Road, and, to my great surprise, I found that particles of the leaves were attracted by the magnet, exactly like tea leaves. Now, as it was too absurd to suppose that the French bean leaves had iron-filings sticking to them, I carefully separated the broken leaves from the substance to which they adhered, and found that it was magnetic oxide of iron, the quantity in 100 grains of the bean leaves being 0'2 of a grain. The question then arose, 'Where did the magnetic oxide of iron come from?' To answer this, I dried a few ounces of the black mould of the garden, and, having searched it with the magnet, I attracted out abundance of the magnetic oxide of iron." THE CHEMICAL NEWS. rescence. Its spectrum, shown at 1 of Fig. 15, consisted Uranic Phosphates. THE salts of this class which we have examined are the following: Mono-uranic phosphate, 2(U2O3)PO5 CaO.2(U,O,)PO +8HO CuO.2(U2O3) PO5+8HO The phosphates, like the arseniates, show a remarkable fixity of spectrum, so that, with the exception of the first, all these compounds show the same spectrum of fluorescence. With regard to their absorptive action, a little more variation is manifested. Mono-Uranic Phosphate, U2O3.2HO.PO5+3HO.-This salt was formed by dissolving uranic hydrate in glacial phosphoric acid. The solution was evaporated in a desiccator until it attained a gelatinous consistency; in this opaque, of a rich green colour, and very billiant fluoof very broad bands, leaving only narrow dark spaces between them. The material in its gelatinous state, and also the dilute solution, fluoresced, and gave a spectrum in which all the bands were displaced downwards in the spectrum, and are more rounded in character; this spectrum is shown at 2 of Fig. 15. The absorption spectra in these two cases are also well marked, and are given in Fig. 16-1 being that of the solid salt, and 2 of the solution. Both salt and solution held an excess of phosphoric acid. The various di-uranic and double phosphates already named yield the same fluorescent spectrum, with no difference but a variation in brightness, and this spectrum is shown at 3 of Fig. 15. It so happened that the first specimen examined was one of di-uranic phosphate prepared in the usual way, which gave a double spectrum, as shown at 8 of Fig. 1. Of this, the upper and fainter series of bands corresponds with the above general di-uranic spectrum, while the other, which disappears on drying, no doubt belongs to some hydrate which we have as yet been unable to identify. The absorption spectra of these salts present a considerable variety of forms. That of the mixed hydrates just mentioned is shown in 8 of Fig. 1, that of the calcio salt at 9 of the same figure, and that of the di-uranic phosphate at 3 of Fig. 16. We have obtained others, but have not yet determined the hydration of the specimens yielding them. It seems likely that these may afford a means of distinguishing some of these salts where their fluorescent spectra are identical. 3 Sulphates. The general rule, that bases of the formula U2O3 require equivalents of a monobasic acid to form neutral salts, is conspicuously violated by the element uranium, and it was this peculiarity in the constitution of uranium salts which prompted Peligot's assumption of the so-called uranyl theory: thus, neutral uranic sulphate has the composition U203SO3+3HO, or, according to Péligot, (U202)OSO3+3HO. This salt is easily obtained by acting on uranic nitrate with concentrated sulphuric acid, or by treating uranic oxide with strong sulphuric acid, and in either case expelling the excess of acid by raising the temperature to about 300° C. The mass is then dissolved in water, and the solution evaporated to the consistency of a syrup; after standing for some time, small lemon-yellow crystals form, which may easily be separated from the mother-liquid. As thus obtained, the salt, according to the best authorities, contains 3 equivalents of water, 2 molecules of which are driven off in a current of dry air at 100° C., but the third molecule is given up only on heating to about 300° C. In this anhydrous state, the great affinity of the sulphate for water is noticeable; each drop as it strikes the mass hisses, and is converted into steam. On dissolving the neutral salt in strong sulphuric acid, and crystallising by spontaneous evaporation, an acid salt, U203SO3+HOSO3, is obtained. This uranic disulphate forms small needles grouped in warty concretions, and is of a much greener hue than the neutral sulphate. As will appear below, the spectrum of the salt is quite different from that of the neutral one. A trisulphate is described by Berzelius, but its existence is denied by Péligot. Its formula, according to the uranyl theory, would be (U2O2)O3S03, which is highly improbable. At present writing, attempts to obtain a trisulphate with a definite spectrum have been unsuccessful |