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ing papers were read after the delivery of the President's vessel a mineral substance. This substance was produced, Address:

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Dr. T. Phipson-A few words on Sponges as a Source of Bromine and of Nitrogen.

Dr. Angus Smith-On a Method of Estimating Carbonic Acid in the Air, with Apparatus.

Dr. Williamson-Report on the Analysis of the Gases evolved from the Bath Waters.

F. Crace Calvert-Notes on the Action of Acids on some Metals and Alloys.

Dr. J. E. de Vry-On the possibility of Manufacturing Neroli in the British Colonies.

Owen Rowland-On the Properties of Parkesine, and its Application to the Arts, Manufactures, and Telegraphy. F. G. Finch-On the Utilisation of Blast Furnace Slags. Dr. A. Voeloker-On recently-discovered Phosphatic Deposits in North Wales.

Dr. Frankland-On the Constitution of the Acids of the
Acetic, Lactic, and Acrylic Series.
Professor Wanklyn-Report on some of the Differences
between the Normal and the Beta Alcohols.
Dr. D. S. Price-On the Action of Light upon Sulphide
of Lead, and its bearing upon the Preservation of
Paintings in Picture Galleries.

Report of the Committee on Gun Cotton.
Manning Prentice-The Progress of the Manufacture of
Gun Cotton and its application to Mining, Military, and
Sporting Purposes.

W. L. Scott-On Action of Alkali Metals on Gun Cotton.
W. L. Scott-On Arseniuretted and Antimoniuretted
Hydrogens.

Smyth, J., jun.-On an Apparatus for the determination
of Ozone, and experiments made therewith.
Dr. de Vry-On the Rotatory Power of several Essential
Oils.

Dr. Macadam-On Esparto Fibre, or Spanish Grass, and
its employment in the manufacture of paper.
Dr. Macadam-On the Results of Agricultural Experi-
ments made in 1864.

D. Forbes-On some Minerals from South America. On
the Colour of Gold as seen by transmitted light.
T. Fairley-On the Reactions of Cyanogen.
Glycocine, with tables.

Note on

Adulteration of Dutch Yeast.-At a meeting of the Sanitary Committee of the Hull Board of Health, held on Wednesday, the chairman stated that his attention had been called by an anonymous letter to the adulteration of Dutch yeast. The letter stated that the recent importations of yeast contained a large admixture of China clay, which was ground as fine as flour by a machine. The chairman remarked that this kind of adulteration occurred a few years ago, and he had reason to believe that it was again being extensively practised. The same anonymous correspondent had again written to him to say that two importers at Bradford had written to the agents on the Continent, telling them that it was very likely that the whole of the next importation would be seized unless the quality was improved, and there was an improvement in the next cargo. The inspector stated that the cargo spoken of as improved was one of the worst samples that had been sent to Hull for some time. He had made inquiries, and had collected samples, some of which he had dissolved in water, when there sank to the bottom of the

and pronounced by two surgeons, who are members of the Committee, to be a kind of aluminous earth. It was resolved that the substance be sent to an analytical chemist for inspection. The average import of Dutch yeast in Hull is about 7000 baskets per fortnight, and during the past fortnight 123 baskets of yeast had been said the Board had no power to interfere with the adulteradestroyed as unfit for human consumption. The chairman tion if it could not be proved deleterious. If the substance take prompt steps to remedy the evil. on analysis was found to be injurious, the Board would

The

North London Industrial Exhibition.-Among the rich displays of optical instruments at the Agricultural Hall, the first that will attract notice is the large case of Mr. T. Ross. This contains a selection of telescopes, microscopes, and photographic lenses of that excellence and finish for which the maker is famous. Among the photographic lenses are some speciniens of the new actinic large-angle doublet, of which we may speak more particularly since some pictures hanging beside the case, and others in the gallery upstairs, are exhibited to show the capabilities of these lenses. We may say, shortly, that the marvellous beauty of these pictures has never been equalled. As the name implies, the doublet is remarkable for the very wide angle of view it embraces. This is well shown in the views of different courts in the Crystal Palace, which could only have been taken by a lens of this kind; and the special adaptation of the lens for taking buildings will be at once apparent to the photographer, who will further remark the sharpness of definition to the very edge of the pictures. Famous as Mr. Ross has been as a maker of lenses, this last is certainly his most valuable contribution to the art of photography. visitor should particularly notice the copy of a map of France made with the doublet, as sharp, clear, and legible as the original engraving. Mr. Ross also exhibits one of Monckoven's enlarging apparatuses, with specimens of untouched pictures taken by means of it. M. Dallmeyer exhibits a case of photographic lenses, well made, of course, but including nothing novel. Mr. How has an extensive display of all kinds of apparatus, among which is the only spectroscope in the Exhibition. This is an excellent instrument, of Bunsen and Kirchoff's form, and is a very useful and cheap piece of apparatus. Mr. How also exhibits a student's microscope, a very well-made instrument, with sliding stage and rapid and slow motion to body, two eye pieces, and a quarter and one-inch object glasses of excellent quality. There are besides a condenser, live-box, and other additions, which make this an exceedingly cheap instrument. Some useful little chests containing blowpipe tests for mineralogists are shown, and a delicate pocket aneroid compensated for temperature for travellers. Some models of crystals in deserve a notice as exceedingly useful for educational purglass, showing the primary and included forms, also poses. Several other cases in this interesting exhibition yet require a notice, but these we must reserve for another occasion.

ANSWERS TO CORRESPONDENTS.

D. T. 0.-Melted sulphur and sand.

H. F-Treatment with sulphuric acid and bichromate of potash would probably effect the first object; for the second, what you sug gost would probably answer. Try a greenish oil.

M. A. W.-1. A process does not occur to us now, but we will look

for and give it next week. 2. Subscribe to the Meteorological Society, who forward reports.

Books Received." Practical Treatise on Coal, Petroleum, and other Distilled Oils," by G. A. Gesner, second edition; "Scientific Review "Proceedings of the American Pharmaceutical Association, 1864;" "Dictionary of Chemistry," Part XXX.

Received. Thallium.

, NOTTS

,

BRITISH ASSOCIATION.

Address to the Section of Chemistry, by the President, Professor W. A. MILLER, M.D., LL.D., Treas. and V.P.R.S., President of the Chemical Society. INTERESTING historical associations are naturally awakened in the mind of the chemist as he enters upon the business of this section of our scientific gathering in the town whose hospitalities we are now sharing; for he is reminded that on August 1, 1774, only ninety-one years ago, Priestley laid, at Birmingham, the foundation of modern chemistry, by the discovery of oxygen.

Yet it seems difficult to realise the fact that there must be some still living who entered life when the chemical nature of the atmosphere was undiscovered, when water was believed to be an elementary substance, when the composition of the ordinary acids, nitric, hydrochloric, and acetic, was unknown, when the discoveries of Galvani had not been made, and when the battery which perpetuates the name of Volta did not exist.

It requires a considerable mental effort to estimate aright the extraordinary progress which chemistry, both in its scientific and in its practical aspect, has made since that day.

foremost of them all, James Watt, who here diversified his engineering labours with his famous investigations into the composition of water. It was at the factory at Soho, too, that Murdoch made the first great experiment on gas-lighting, at the illuminations for the short-lived peace of Amiens; and it was in Birmingham that Dr. Roebuck, in the middle of the last century, erected the first leaden chamber for the making of sulphuric acid, and thereby inaugurated the most important of the chemical manufactures of this country.

Nor has Birmingham failed in more modern times to maintain her reputation in connexion with the chemical arts. Here, twenty-five years, ago, Elkington founded the first establishment, in this country, for carrying out the processes of electro-plating and electro-gilding. Here Askin made the nickel of commerce, with its companion metal, cobalt, as oxide-articles that might_vie in purity with the products of the laboratory. Here Chance has established a manufactory of optical glass which specially calls for acknowledgment on the part of the student of science; and here Sturge and Albright have erected the only manufactory for red phosphorus which the country contains.

Vast as is the modern development of experimental science, it yet cannot excite much surprise that, with the exception of that portion which falls within the domain For example, the development of the laws of combi- of the mathematician, science until recently has been nation-the determination of the equivalent proportions systematically excluded from the general course of eduof the elementary bodies-the art of chemical analysis- cation, and has been followed in the majority of instances the atomic theory-the isolation of potassium, with the by those only who commenced its study for professional consequent discovery of the compound nature of the objects. Yet can we wonder at this, when we remember alkalies and earths-and the marvellous developments of that the science of chemistry and many entire branches the organic department of chemistry, exhibit some of of experimental physics, including voltaic electricity, the most striking points in the progress of the science; electro-magnetism, thermo-electricity, the phenomena of whilst in the chemical arts we may mention gas-lighting polarised light, of photo-chemical action, radiant heat, -the manufacture of stearic acid and other fatty acids and others, are, as already stated, less than a century for candles-the industry of petroleum and paraffine- old? But the great strides that they have made in that the chemical process of bleaching by chlorine-the pre-interval, the social changes that they have introduced, paration of carbonate of soda from common salt, and the and the additional powers that they have conferred upon extensive alkali trade. The discovery of iodine and man, will vindicate their importance as necessary branches bromine, and their varied applications as remedial agents of knowledge to be acquired; whilst the more just and otherwise the fascinating processes of photography appreciation of the methods of investigation which they -the development of the trade in beetroot sugar-the pursue will establish their claim to be regarded as instruextraction of quinia, morphia, and all the vegetable ments in training the mind, and shaping the intellectual bases, these and other processes of chemical manufac- development of the future. ture too numerous to mention, are all subsequent to, and may be said to be in nearly every case consequent on, the great discovery of oxygen.

Those whose education was based upon the linguistic system almost exclusively, as was the case both before and after Priestley's time, could not be expected to Well may we sympathise, now, in the sanguine anti-realise the magnitude and true bearing of science and its cipations of Priestley himself, expressed in the preface to the volume in which this discovery is recorded, " Experiments and Observations on Different Kinds of Air," vol. ii., p. 7:-"In reality, this is not now a business of air only, as it was at the first; but appears to be of much greater magnitude and extent, so as to diffuse light upon the most general principles of natural knowledge, and especially those about which chemistry is particularly conversant. And it will not be now thought very assuming to say, that, by working in a tub of water or a basin of quicksilver, we may perhaps discover principles of more extensive influence than even that of gravity itself, the discovery of which, in its full extent, contributed so much to immortalise the name of Newton."

But it is not alone with the name of Priestley that we associate the progress of chemistry in Birmingham. Grouped around the father of pneumatic chemistry were several remarkable men who then either resided at Birmingham or frequently met there, including Matthew Boulton, James Keir, Dr. Withering, Dr. Darwin, and, VOL. XII. No. 303.-SEPTEMBER 22, 1865.

educational value. Now, however, the case is altered; and it is a subject for congratulation to reflecting men that the introduction of the scientific element into the ordinary course adopted at our public schools is at length attracting serious attention, and that its importance has been insisted on in both Houses of the Legislature. The practical instinct of the nation is becoming alive to the necessity of making certain portions of the training of our youth consist in the systematic study of the elementary parts of properly selected branches of science; and it behoves all who are themselves engaged in the pursuit of science to consider in what way they can themselves aid in forwarding this object.

I need not here advert to the exploded notion that the acquisition of the truths of science can in any wise endanger those of revelation; for truth is ever consistent. But it may not be superfluous to reassure the minds of some who imagine that science, like a fresh invasion of Vandals, will extinguish scholarship and classical learning. Language must indeed ever form the basis of

our system of education; for it is the key that unlocks the stores of knowledge; and no languages are so fitting to form the groundwork as the tongues of ancient Greece and Rome, irrespective of the treasures of philosophy, eloquence, poetry, and history which they contain. They have that intellectual finish and completeness which belongs only partially to science. A moderate amount of classical knowledge can be, as, indeed, it ought to be, attained by every so-called educated mind, while for him who would carry the critical faculty to a high state of cultivation, the study of the classics affords the means. These tongues constitute the basis of many of the modern European languages; and an acquaintance with their literature imparts a cultivation and a polish that it is almost vain to seek from any other source. Just as some minds seek to attain distinction in the wide domain of philology, other minds, as vigorous, though differently constituted, delight in the study of natural laws and affinities. It would be a hard thing to say that provision should not be made in our schools for the latter, as wide and liberal as it has been for the former.

It is not to be supposed that, because science is to form a part of the education of every gentleman, therefore it will constitute the pursuit of his mature years. What is needed is that he possesses sufficient knowledge of its principles to qualify him to appreciate the advances which science is making, and to enable him to contribute intelligently towards its progress.

It is certain that if science is to form a useful portion of the education of a boy, it must be undertaken with the determination to deal with it as a matter of study: the same pains must be taken to ascertain that each boy understands the principle, for example, of the air pump, or the meaning of the thermometric scale, as that he comprehends a rule in syntax or the analysis of a sentence. To do this, however, the instruction given must not be limited to a dry lecture on the principles of some branch of science once a week. These principles must be logically unfolded, and illustrated, when necessary, by experiments, and the structure of machines and apparatus explained by suitable diagrams; the boys must be taught to take notes of each lecture; and the ground covered must be made secure by following up the lectures with frequent examinations, both oral and written. These are as necessary to the successful study of a science as the writing of exercises, or the practice of construing, is to the accurate study of a language. Science is not merely to supply her facts; she is to be employed to develope the powers of the mind, and to discipline them for action. Hence it is of far more importance to instil principles, and to cultivate precision in observation, in thought, and in description, than it is to load the memory with mere facts, however valuable. In short, the system of cramming is to be eschewed, whilst the formation of habits of comparing, reasoning, and judging is to be encouraged in every way.

It may at first be difficult to meet with well-trained and competent teachers; but when once the want of instruction in science is proclaimed, the teachers will soon be forthcoming. Some years will, no doubt, elapse ere science is admitted to take equal rank, as a means of education, with the study of classical literature. Still it is but a question of time; and we cannot but hope that our universities, following up the commencement which the youngest but not the least active amongst them, the University of London, has made in the establishment of degrees in science-we cannot but hope, I say, that the heads of our universities will ere long feel it to be their duty, as unquestionably it will be their

wisdom, to place themselves at the head of this new movement, which is destined to exercise so wide an influence upon the education of our people.

But it is time that we proceed to take a rapid survey of some of the principal points in the progress of chemistry during the last twelve months. The course of chemical discovery since our meeting last year, though not marked by any very striking novelty, has nevertheless been steadily advancing. Ideas previously thrown out have been discussed and developed, and many of them are leading to new discoveries, or are being applied to explain phenomena before wrapped in obscurity. Amongst the problems which have, for some time past, been engaging the minds of philosophical chemists, few are of greater interest than those connected with the idea of the atomicity of the elements. It is well known that chemists now distinguish between the atomic weight and the equivalent of an element; also, that owing to the labours of many distinguished men, amongst whom the names of Williamson, Kekulé, Odling, Cannizzaro, and Wurtz are the most prominent, a classification of the elements into families has been made; and that this classification rests upon what is known as the atomicity of the elements. One group of the elements, like potassium and chlorine, is regarded as monatomic, or usually equivalent in functions to one atom of hydrogen; a second, like oxygen and sulphur, is diatomic, or equivalent in functions to two atoms of hydrogen; a third group, like nitrogen, phosphorus, and arsenic, is triatomic or equivalent for the most part to three atoms of hydrogen; while a fourth group, like carbon and silicon, is tetratomic, or equivalent in functions to four atoms of hydrogen, and so on.

It would lead us too much into detail, were I to attempt to show how this idea of the atomicity of the elements has been applied, and is still in process of application, to the study of the formation of compounds in general, how it endeavours to explain the existence of a limit to their number, and how it even teaches us to anticipate their possible varieties.

Among the subjects connected with its development is its bearing upon isomerism, or the remarkable fact of the existence in many cases of two or more bodies of different properties but yet composed of the same elements combined in identically the same proportions. Upon this subject, which, at our last meeting, was characterised by Dr. Odling as the chemical problem of the day, a suggestive theoretical paper was published, about twelve months ago, by Dr. Crum Brown; whilst, in the same direction, Cahours, Kekulé, Beilstein, Fittig, and several other chemists have published valuable experimental researches. Inquiries of this kind are now acquiring special importance from the numerous cases of the formation of such isomeric bodies by the methods of synthesis and substitution, which are daily multiplying.

Closely connected with the same subject are the investigations into the constitution of the more complex organic acids, which have been prosecuted so actively during the last five or six years, and which, in the hands of Kolbe, Franklin, Perkin and Duppa, Kekulé, Wurtz, and their pupils, have made such rapid progress.

During the past year Frankland and Duppa have especially signalised themselves by their researches upon the lactic and the acrylic series. Two years ago, Frankland, commencing with oxalic ether, and acting upon it with zinc ethyl, obtained from it leucic ether by substituting ethyl for a portion of the oxygen contained in the oxalic ether; and afterwards, conjointly with his

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In these and kindred investigations, the necessity for the introduction of fixed principles of nomenclature for regulating the construction of names for the recently discovered compounds has been sensibly felt; and indeed the changes in notation rendered necessary by the alteration in the values assigned to the atomic weights of many of the chemical elements have rendered a general revision of the system of chemical nomenclature a matter of pressing importance. Probably few subjects could more usefully occupy a portion of the time of this section during the ensuing week than a thoughtful consideration of the changes which it may be expedient to introduce. The meeting of chemists from various parts of Europe with many from distant parts of our own country affords an excellent opportunity for discussing a subject of this kind, where any conclusions, to be practically effective, must secure the concurrence of a majority of the active cultivators of the science.

Did time permit, it would be easy to mention other investigations in the organic department of chemistry, scarcely less interesting than those already alluded to, such as those on the synthesis of the aromatic acids by Kekulé, who has prepared both benzoic and toluic acid by the graduated action of sodium on an ethereal solution of bromo-benzol, and of bromo-toluol whilst submitted to a current of carbonic anhydride, as, for instance, may be explained by the equation

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H,Br+ Na2+ €02 = ́Ña¤ ̧H ̧(¤02) + NaBr. or such as those of Maxwell Simpson and of Baeyer on the artificial formation of tribasic acids; and, referring to methods of research, stress might be laid on the important aid afforded by the extended use of the amalgam of sodium as a reducing agent, and on the similar but still more remarkable reducing effects of hydriodic acid -processes, indeed, not new, but the value of which till quite recently has only been partially recognised.

Passing allusion only can now be made to some of the processes of mineral and metallurgic chemistry, such as the improvements in the details of the process for preparing magnesium, the comparative facility with which the recently discovered metals thallium, rubidium, and caesium and their compounds may be obtained, and the application by Redtenbacher of his observation of the sparing solubility of their alums to the extraction of the new alkalies from the lithium residues of commerce. Of indium, too, the latest of the newly discovered metals revealed by the spectrum, it must suffice to say that it has been obtained in quantity which places its existance as a distinct metal beyond question. I am indebted to my friend Professor Roscoe for the small specimens of the metal and its sulphide now upon the table.

An extensive branch of industry is now springing up in the improved methods of voltaic depositions of the metals. Weil has, by the use of an alkaline solution of tartrate of copper, contrived to coat iron and steel with a tough closely adherent sheathing of copper, by simply suspending the articles to be coated by means of a wire of zinc in the metallic bath. No battery is required. Lead and tin may in a similar manner be deposited on copper, iron, or steel, if the oxide of tin or of lead be dissolved in a bath of strong solution of caustic soda.

I must, before I conclude, advert to one or two interesting additions to our knowledge upon the side where chemistry and physics meet. Few results, perhaps, were more unexpected than those obtained by Deville and Troost upon the permeability to gases of certain dense metals at elevated temperatures. They have proved that platinum and iron, when white-hot, become for the time porous, and are rapidly permeated by hydrogen, which will even pass out under the pressure of the atmosphere and leave a vacuum almost perfect within the tube. In one form of these experiments, tubes of hammered and of cast platinum (which in one case was as much as a twelfth of an inch in thickness) were fitted by means of corks into the axis of a shorter and wider tube of glazed porcelain; a slow current of pure and dry hydrogen was then maintained through the porcelain tube, whilst a current of dry air was transmitted through the platinum tube. At ordinary temperatures no change was observed in either gas. A fire was then lighted around the outside of the porcelain tube, and gradually raised until the heat became very intense. At 2000° Fahr. the oxygen contained in the air had entirely disappeared; nothing but nitrogen mixed with steam passed out of the platinum tube, hydrogen had passed through the pores of the platinum and entered into combination with the oxygen of the air within; whilst at still higher temperatures the moist nitrogen became mixed with hydrogen. As the tube cooled, the same phenomena occurred in the inverse ofder, till, when the ordinary temperature had been regained, no diffusion of hydrogen was perceptible, and unaltered air was collected from the platinum tube. Analogous results were obtained when a tube of soft cast steel was substituted for that of platinum, though the thickness of the steel tube was an eighth, or in some cases as much as a sixth of an inch.

From these experiments one practical conclusion deducible is, that air-pyrometers, the bulbs of which are formed of iron or platinum, cannot be relied on when employed for measuring elevated temperatures; glazed porcelain, however, was found to confine the gases completely.

Curious as these results are, they are but parenthetical in another series of more general bearing, in which Deville has for some time been engaged - viz., the phenomena of dissociation, as he has termed the partial decomposition which compound gases experience under the influence of a temperature more or less elevated.

A very striking result was obtained by the use of an apparatus similar to that employed in the experiments just described, but in which a brass or silvered tube was substituted for the platinum or iron tube. A rapid flow of water was maintained through the metallic tube, so that it was kept quite cool, whilst the outer porcelain tube was gradually raised to an intense heat as before. On transmitting a current of pure and dry carbonic oxide through the porcelain tube, the lower part of the surface of the cold metallic tube became covered with deposited carbon, whilst a portion of the carbonic oxide,

by combining with the oxygen previously united with this carbon, became converted into carbonic anhydride. Sulphurous anhydride was by similar treatment resolved into sulphur and sulphuric anhydride; and even hydrochloric acid was partially separated into hydrogen and chlorine. These experiments are intimately connected with the attempts made to explain the cause of certain exceptions to Ampère's law, that equal volumes of gases or vapours contain the same number of molecules of each. Chemists now generally assume that the molecule, both of simple and of compound bodies, forms two volumes of vapour, and consequently that the molecular weight of any substance corresponds with the number which represents twice its density when referred to the density of hydrogen, if this be taken as unity. But there are exceptions to this law: pentachloride of phosphorus, hydrochlorate of ammonia, hydriodate of phosphuretted hydrogen, and various other bodies, instead of forming two volumes when one molecule of each is converted into vapour, yield four volumes.

In order to explain these anomalies, Kopp and Cannizzaro suppose that, at the temperature at which the vapour-densities of these compounds are observed, the bodies are temporarily decomposed, and, instead of forming one homogeneous vapour, are at the time of the observation really composed of a mixture of vapours. In certain cases this explanation is probably the true one; but its general acceptance has been disputed by Deville himself, though his results on dissociation seem, to cursory observation, to be in its favour; and it must be admitted that, up to the present time, the arguments and experiments which he has brought forward in opposition to the views of Kopp and Cannizzaro have not been satisfactorily answered.

No sufficient proof, for example, has yet been adduced that the well-known anomalous cases of nitric oxide, chlorous anhydride, hydrosulphide of ammonium, cyanine of ammonium, and various other salts of ammonium and the volatile bases are due to dissociation of their components.

This subject is one, however, too intimately connected with the molecular theories at present under discussion to remain long in its actual state. New experiments and evidence will no doubt be forthcoming, which will throw further light upon the cause of these outstanding exceptions.

SCIENTIFIC AND ANALYTICAL CHEMISTRY.

On a New Series of Bodies Intermediate between Nitric Acid and Ammonia, by Dr. A. W. HOFMANN, F.R.S. IN the course of a discussion on a paper read at the Birmingham meeting of the British Association, Section B, by Dr. C. Calvert "On the Action of Acids on some Metals and Alloys," Dr. Hofmann asked Professor Calvert whether, in his experiments on the action of acids, and more especially of nitric acid, upon the metals, he had met with some of the extraordinary bodies lately observed by Dr. Lossen. This young chemist, at one of the late meetings of the Berlin Academy, had laid before that body an account of several substances which had attracted general attention. It was well known that among the products of the action of nitric acid upon certain metals ammonia invariably occurred. But it appeared that ammonia was only the last product of the reaction, and that a whole series of intermediate com

pounds existed between nitro-ammonia acid, the substance acted upon, and the .ast product of its reduction. One of these bodies Dr. Lossen had succeeded in isolating. It was a compound which, from its composition, might be termed protoxide of ammonia, having, in fact, the formula H.NO. This substance, like ammonia, combined with acids, producing a series of magnificent salts remarkable for the facility with which they crystallise. The simplest method of producing this interesting compound consisted in submitting nitrate of ethyl to the action of metallic zinc in the presence of an acid. It would be observed that the derivation of the new body from nitric acid was perfectly analogous to that of aniline from nitrobenzol.

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On Some Salts of the Peroxide of Thallium,
by A. STRECKER.*

THE compounds of thallous oxide with acids have been for the most part studied and described, but little has been said of the salts of thallic oxide (T103), except that they are hygroscopic and easily decomposable. The author, therefore, prepared some of the salts, and submitted them to investigation. He prepared the oxide by adding hypochlorite of soda to a solution of thallous chloride in carbonate of soda. The two solutions, when mixed in the cold, gradually deposited a brown precipitate of thallic oxide, which was washed by decantation. A boiling saturated solution of thallous chloride in carbonate of soda added to hypochlorite of soda gives a dark brown precipitate of thallic oxide, usually mixed with a small quantity of chloride, which may, however, be changed into peroxide by digesting the precipitate with hypochlorite of soda.

According to Lamy, the peroxide precipitated by an alkali from the perchloride retains, after drying at 100° C., one equivalent of water; but Strecker found the entire loss, on heating the oxide to redness in a stream of dry air, was only o'6 per cent.; the formula TIO, + HO would require 3.8 per cent. of water.

Thallic Sulphate.-Thallic oxide easily dissolves in warm dilute sulphuric acid. On evaporating the solu tion, thin, colourless plates separate from the concentrated liquor; these must be collected on a filter paper and separated from the mother liquor by pressure; washing with water decomposes the salt. Dried in the air, the salt has the composition TIO3,3SO, + 7HO; at 220° it loses six equivalents of the water, and becomes TIO3,3SO3 + HO.

Sulphate of Thallic Oxide and Soda.-A solution of thallic sulphate in dilute sulphuric acid added to saturated solution of sulphate of soda gives colourless * Abstract Annalen der Chem, und Pharm., Aug., 1865, p. 207.

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