The mineral is therefore a hydrated phosphate of alumina and copper with a little lime." Dr. Foster states, with reference to the discovery :-"In looking over some specimens of chalcosiderite [a mineral not given by Bristow, and which the writer of this article therefore supposes to be also a new species, containing copper and iron] I noticed a bluish green mineral which was different from the rest, and subsequently, on calling the attention of Capt. Hosking, of West Phoenix, to the mineral, I obtained several pieces from him." It certainly shows great sagacity on the part of Dr. Foster to have suspected the presence of phosphoric acid in this mineral, unless chalcosiderite also contains that acid, but it is unfortunate that he should have omitted his reasons for the surmise from his analysis. It will be observed that, for the detection of alumina and lime, the "wet way " has to be resorted to, while the iron present is not detected at all. Henwoodite.* (1.) Appearance.-A rounded aggregation of lenticular crystals; pale green-blue. (2.) On Al plate in O.P.—Colour changed to chocolate brown. (a.) Adhered to a magnet (apparently due to particles of Goethite, which were carefully removed from the crystals). (b.) Green pyrochrome; might be due to copper, molybdenum, barium, phosphoric acid, &c.; no sublimate, no sulphur reaction. (3.) Crushed (2) between agates, and treated some minute particles on a bead of boric acid in O.P.-Bluegreen pyrochrome+copper. (a.) Streaks of curdy matter, heating into opalescence = phosphoric acid or water; see (5). (b.) White amorphous fragments; black do., with opaque. = = calcium insoluble rusty matter round. White balls phosphate, one grey ball, one black ball, all The whole bead was interspersed with shining crystalline spots SiO2? (4.) Added a fragment of pure lime under O.P.-A large clear ball; pale yellow-green hot, nearly colourless cold FeO. (A particle of cupric oxide without iron colours a similar ball brilliant chrome green, hot or cold.) = (5.) Clarified the opalescent bead with potassium carbonate and magnesium sulphate. (a.) Added fresh boric acid under Ö.P.-The clear bead became opalescent on cooling = presence of phosphoric acid. (6.) Heated another piece of (1) with pure oxide of lead on a charcoal mortar on aluminum plate.-Fused with great effervescence to a crystalline mass of plumbic phosphate, with minute balls of copper interspersed. (This new test for cupric phosphate is best seen with Libethenite. The copper disengaged seems beautifully pure.) (7.) Heated a fresh piece of (1) with sodium carbonate on Al plate in O.P.-Fused to a brick-red mass Cu2O. (8.) Crushed (7) in (a) forceps|| on agate slab, and boiled in water acidulated with boric acid.-Two precipitates (a) brown, flocculent, above; and (b) brick-red, below Cu2O. (9.) Treated (8 a) in a boric acid bead under O.P.Great opalescence = phosphoric acid (as was seen by (5 a); some opaque white balls; ditto ditto fragments; two black balls; several clear small crystals = SiO2. *I had the great advantage of seeing Mr. Collins's quantitative analysis of the mineral in the Society's journal, but having lent my copy to a pupil (Mr. Lombard:), I only remembered that Henwoodite is a hydrated phosphate of alumina and copper." Abnormally coloured flames are called "pyrochromes" by me. See page 186, "Pyrology," "The Test for Phosphoric Acid." # See page 69, Ibid, Article, " Matèriel." 157 ometer. DURING the last three months several papers have been read before the French Academy respecting the radiOn reading these papers I find that the various experiments performed are in general repetitions of some which I have devised during the four years I have been working at the subject. The descriptions of my experiments and the results I have obtained have been communicated by me from time to time to the Royal Society. Unfortunately, however, these papers do not appear in the Philosophical Transactions until twelve or eighteen months after they have been read, and according to custom I could not savants had seen my papers they would have found that I communicate them to other learned Societies. If these had not only tried the experiments, but that I had also discussed the evidence both for and against the several theories they have advanced to account for the action of the radiodescribed in the third and fourth parts of my paper: these The experiments with radiometers are almost all were read before the Society on February 10th, 1876, while in parts one and two I have considered the various supposed causes of the phenomena. meter. In the Comptes Rendus for July 3rd, 1876, M. Govi describes an experiment showing the action of dark heat on the instrument. This experiment is described in the paper read before the Royal Society on February 10th, and was also shown at a Soirée of the Royal Society on April 5th. The radiometers described by MM. Alvergniat and Gaiffe, in the Comptes Rendus of July 24, differ in nothing from those that I had previously caused to be constructed, and which are also described in the paper referred to above, while M. Ducretet's experiment of pouring ether upon the case of the radiometer was demonstrated to my audience on the occasion of my lecture at the Royal Institution, on February 11th, 1876. At the Royal Society Soirée, April 5th, I exhibited the turbine-radiometer, and this is also described in the paper read on February 10th. In the Comptes Rendus for June 19th a similar instrument is explained by M. de Fonvielle. With regard to the cause of the rotation, M. de Fonvielle adheres to the theory of emission; while M. Fizeau, in the Comptes Rendus of May 29th, attributes the action to, first, a slight excess of temperature acquired by the discs as compared with the ambient medium under the influence of light; secondly, to the unequal powers of emission and absorption of two opposite surfaces (black and polished of each disc; thirdly, to the presence, in the apparatus, of a smali In the No. for June 19th quantity of elastic fluid. M. Govi refers to Fresnel's experiments, which he will find described in my paper read in December, 1873; and he also says that, if the thermic currents of rarefied gases contained in the receiver do not suffice for explanation of the facts observed, there is another explanation, namely, * Translated from a Letter to Count du Moncel, published in the Comptes Rendus, September 11, 1876. 158 Action of Alcohol on the Brain. CHEMICAL NEWS, The more general question of what becomes of alcohol in the system has been far more deeply studied. I do not propose to enter into it except so far as to indicate our present absolute knowledge on this point. Thudichum was the first to determine quantitatively the amount of alcohol elimininated by the kidneys from a given quantity of alcohol administered, and the result was sufficient in itself to disprove the elimination theory, at that time prevailing very widely. by the dilatation by heat or the contraction by cold, | from which he concluded that "alcohol acts principally, of the gaseous layers which all bodies retain on their though not exclusively, on the nervous centres by means surface, even when placed in an absolute vacuum. In of absorption, and consequently through the circulation;" the Comptes Rendus, June 26, M. Ledieu bases his ex- and, further, that it also "exerts a slight but decided action planation on a mechanical action of the "ether" perpen- on the nervous centres through the nerves, independently dicularly to the direction of its rays of propagation, of the circulation.” and not in the same direction as those rays. Others ascribe the action to electricity. Now, in my paper read before the Royal Society in April, 1875, I have discussed all these theories, and described the experiments consequent upon them. I have there shown that, while either of the theories will account for some of the phenomena, it is not so easy to find an explanation which will satisfy all the conditions of the problem. Referring to M. Hirn's communication in the Comptes Rendus of June 26, I may mention that on March 30, 1876, I read a paper at the Royal Society on the "Movement of the Glass Case of a Radiometer," in which I showed that the internal friction, either of the steel point in the glass socket, of the vanes against the residual air, or of both these causes combined, was considerable; and on the 15th of June last I stated, in a paper to the Royal Society, that the evidence afforded by my latest experiments is to my mind so strong as almost to amount to conviction that the repulsion resulting from radiation is due to an action of thermometric heat exchanged between the surface of the moving body and the case of the instrument through the intervention of the residual gas. This explanation of its action is in accordance with recent speculations as to the ultimate constitution of matter and the dynamical theory of gases. MEMOIR ON THE THE question of the action of alcohol on the nervous system has long occupied the attention of physiologists, but the researches that have been conducted at various times by various workers have not led to any very decided results. They have, moreover, been directed to a study of the channels through which the alcohol may be supposed to act, rather than to the action itself. This, indeed, was almost unavoidable, for although there were many theories regarding the modus operandi of alcohol in the system, and especially in regard to the nervous system, our knowledge of the nervous system itself was very imperfect, and remained so until quite recently, when, by the researches of Thudichum, the chemical constitution of the brain has been elucidated. (More recently, papers on the specific points of the same subject have been published by Thudichum and the author.) The possession of this knowledge enables us to indicate fresh lines of research from which the physiological action of alcohol may be studied. In 1859 Dr. Marcet, F.R.S., read before the British Association a paper on this subject, in which he endorsed the views of Dr. J. Percy, who had, in 1839, published a research on the presence of alcohol in the ventricles of the brain. Dr. Percy concluded "that a kind of affinity existed between the alcohol and the cerebral matter." His investigation was of an experimental nature, and he states that he was able to procure a much larger proportion of alcohol from the brain than from a greater quantity of blood than could possibly be present within the cranium of the animal upon which he operated. Dr. Marcet in considering these researches alludes also to the researches of L. Lallemand, Michel Perrin, and Duroy, "who withdrew the blood from the brain in cases of poisoning with alcohol, and succeeded in extracting alcohol from the cerebral substance, thus free from blood." (loc. cit.) Finally, he describes physiological experiments, * Read before the British Association, Glasgow Meeting (Section D.). The subject, however, was followed up by Dupré and others, and the results of their continued researches may be given in Dupré's own words (See Practitioner, March, 1872), from the abstract of a communication to the Royal Society: "(1.) The amount of alcohol eliminated per day does Now it must be pointed out in regard to all these researches that they have reference to quantities of alcohol, which are certainly below those quantities which by consumption give rise to "delirium tremens." In this disease the amount of alcohol eliminated is much greater, and, in any case, the fact that alcohol is not eliminated does not prove what becomes of it. Certainly we know that it is ducts of that oxidation nor the time which is necessary oxidised in the circulation, but we neither know the profor its completion, and if there be any truth in the researches into and remain with the cerebral matter or other tissues of Percy and others alluded to, the alcohol may be absorbed until, by the obtaining of necessary conditions, it may be re-absorbed into the circulation and oxidised there. Meanwhile, assuming it to remain for a time with the cerebral matter, how may it be supposed to act in order to bring about the disease called "delirium tremens ?" It had been my intention to determine quantitatively the amount (if any) of alcohol which may remain in the brain-substance of animals to which large quantities of alcohol may be administered. In this matter, however, I have been disappointed, and my researches therefore go upon the assumption that Percy was right in his conclusions. I have pointed out in a previous publication, "On the Relations of Chemistry to Physiology and Pathology with special reference to the Brain." that alcohol may be supposed to act, when present in large quantity, upon brainmatter in one of two ways, or in both. (See CHEMICAL NEWS, vol. xxxiii., p. 79.) The brain, with its water of enables it to assimilate matters from the blood which colloidation, has a mobility of ultimate particles, which readily diffuses through it on the one hand, and a penetrability which allows of the crystallisable products of life being carried away by the blood on the other side. Now, from what Thudichum has found regarding the chemical constitution of the brain (See "Report of the Medical New Series, No. III.), it may be supposed that alcohol Officer of the Privy Council and Local Government Board," would act on it as a whole by robbing it of its mobile character, so essential to its healthy functions, and consequently impair its power to assimilate its food and its CHEMICAL NEWS, Oct. 13, 1876. Action of Alcohol on the Brain. power to throw off the products of its life functions: or alcohol may be supposed to act by dissolving traces of the principles of which brain-matter is composed-albumin, kephalines, myelines, and cerebrines, &c. I now proceed to describe the experiments I have conducted to study these points before stating the conclusions which follow from them. As it was impossible to carry on my experiments either upoh live beings or upon human brains, I had recourse to ox brains, which in each case were removed from the skull after death and immediately before experimenting upon them. Experiment I.-In this experiment an ox brain, recently removed from the skull, was maintained by means of a water-bath, at a temperature of the blood, suspended in water containing varying amounts of alcohol, or in water alone for seven hours in each case. The amounts of water and alcohol employed in the various experiments were as under: Alcohol 16 per cent. B. 1000 C. 1000 400 27 400 19 27 I. 1000 The method of examination employed consisted in the evaporation of the various extracts to dryness in a waterbath and the analysis of the products. The amount of matter which passed into solution gradually diminished with each extraction, while the nature of the matters dissolved appeared identical or nearly so, with the exception of the first extract. This contained more albumen, and what may be called waterextracts of the brain. These matters, to be presently described, would appear to have been present in great part diffused through the brain, not in a state of strong combination; they might, therefore, be regarded in part as food-forming matters, or as brain excrementitious educts. As much as was necessary of the small amounts of matter dissolved in each case was used for ascertaining the specific nature of the constituents. Those quantities remaining over were united and examined in bulk. Among the constituents were observed myeline, and identified by the test with sulphuric acid and sugar; by its deposition from an alcoholic solution on cooling; by its CdCl2 salt; and the presence of phosphorus both in the free body and the CdCl2 salt.-No kephaline dissolved. A considerable amount of water extractives, containing a phosphorised principle insoluble in strong alcohol, and not before recognised.-Potassium, chlorine, and alumina. Before the conduction of trial F. the brain was allowed to stand in water during twelve hours to wash it free from any alcohol that may have been left in it from the previous experiments. The extract in this experiment certainly contained myeline, and also the phosphorised principle insoluble in strong alcohol, besides alumina. A form of cerebrine was also found amongst the dissolved matters, no matter whether alcohol had been used or not. It was established by re-crystallisation from alcohol, inability to form a CdCl2 salt, and its freedom from phosphorus. It should be observed that in the later extractions, although much alcohol was employed, the amounts of matter dissolved were extremely small. This gradual decline in the amount of matter extracted may be ascribed to two causes. First, apparently there existed diffused through the brain matters in a state of solution, left there doubtless by the blood; but, secondly, the brain gradually grew harder and firmer, until finally its mobility of particles was almost entirely lost. Such a growth in the 159 0'19 grm. L. 1000 water. Nature.-All these extracted matters seemed of similar nature, and all gave the purple reaction with H2SO4 and sugar. For analysis see Experiment III. Experiment II. seemed to indicate (see F.) that when the amount of alcohol exceeded a given quantity more matter was dissolved, and in order to confirm this, and to ascertain its nature, the following Experiment III. was carried out on a new ox' brain. Each extraction, like as in experiments I. and II., was sustained during seven hours at a blood-heat. The results are tabulated. 160 Action of Alcohol on the Brain. {° CHEMICAL NEWS, Oct. 13, 1876. This experiment gives rise definitely to three conclusions. | being in water only at a blood-heat for five hours it had a Allowing for that decrease in the amounts of matter dis- specific gravity of 1007. solved, and caused by the hardening of the brain, it would appear (2.) If that quantity be exceeded (see O., P., Q.) much more matter dissolves. (3.) That while the influence of hardening the brain is confirmed by Q., it would appear that in healthy life, when the brain is of a very mobile character, similar quantities of alcohol to those here used would dissolve a considerable amount of matter from the brain. The matters extracted in Experiments II. and III., remaining over that used previously, were united and analysed together. On extraction with ether a red-coloured solution was produced, from which alcohol precipitated 07 grm. kephaline, (C42H79NPO13), which was identified by its properties. The ether alcoholic mother-liquor contained 20 grms. more kephaline. The matter insoluble in ether was extracted with boiling 85 per cent alcohol. From the alcoholic solution 06 grm. of mixed cerebrine and myeline, C34H68N2O8 and C42H83NPO,, was deposited on cooling. The motherliquor contained a further quantity of 40 grms. The matter insoluble in alcohol was now exhausted with boiling water, and the extract on evaporation to dryness weighed 4 grms. It constituted ordinary water-extracts of brain. The matter left insoluble by the water weighed 2.5 grms., and was chiefly albuminous in nature, making a total of 13.8 grms. matter. Experiment IV. was designed to ascertain what influence (if any) was introduced by skinning the brain previous to extraction. This was done because the conditions obtaining in life are such as to allow more readily of the passage of alcohol-bearing liquid through the brain-matter than can be secured after death. The brain was skinned after extraction A. and before B. The results, while they sustain the conclusions previously given, are not indicative of any new feature. Weight of Matter Dissolved. Grms. 2.20 4'10 Lost 600 39 600,, 34 1.60 0.66 Experiment VI.-In another case an ox brain had a specific gravity of 1031; but after being in a solution of 38 per cent alcohol for five hours at blood-heat its specific gravity was only 1005, and on continuing the experiment for another five hours the specific grauity became 1007. In Experiment V. the decrease in the specific gravity was brought out by swelling, for the weight of the brain where alcohol was used, the loss in specific gravity must had not materially altered, whereas in Experiment VI., have been introduced by the fixation of water, for the brain had gained materially in weight. To sum up and conclude, it would appear from the results attending my investigation that alcohol has no more chemical effect on the brain-matter than water itself, so long as it is beneath a certain proportion to the total volume; but if that proportion be exceeded the brain principles, including kephaline, begin to dissolve and pass into solution, while the specific gravity of the brain is at the same time affected, both by the loss of matter and apparently the assimilation of more water. Meanwhile, water itself has a strong action on brain-matter, for it is capable of dissolving also certain principles slowly from the brain, for instance, cerebrine, myeline, &c., but no kephaline, and at the same time the brain-matter swells and attains a smaller specific gravity. It is extremely hard to follow these ideas into life, and to comprehend in what way each or all of these modes of action of water and alcohol on the brain may be influenced by the other matters present in blood. Thudichum has shown that the state of the bra'n in life must vary according to every change in the state of the blood, and therefore what I have said of the action of water is probably true in life, in cases where the serum is very watery; but if the serum be rich in salts, those salts, by a power of combination which they have for the brain principles, would preserve the integrity of the latter. On the other hand, it is not so easy to see how any of the matters we know to exist in the blood could prevent alcohol, if it the brain or from dissolving traces of the principles to be were present in sufficient quantity, either from hardening henceforth carried away in the blood. If future physiological research should prove the absorption of alcohol to any extent by the brain, and its retention thereby, it would not be difficult to conceive, from what has gone before, how the alcohol would interfere with the life-functions of the brain and produce disease. Further researches are in hand. In conclusion, I have the pleasure to acknowledge Dr. Thudichum's kindness in placing his laboratory at my disposal. F. 1000 grms. water G. 340 grms. A., 600 W., The matter extracted in this experiment was submitted to analysis, and found to contain no kephaline, but gave I'I grms. of myeline (including any cerebrine present), and 125 grms. of albumin; the rest was constituted of potassium chloride and extractives, including a trace of lactic acid. I now wished to demonstrate by numbers, if possible, the fact that brain-matter (after death) increases in hardness, with loss of its penetrable character, when maintained at the temperature of the body, and immersed in water or water containing alcohol. 1 therefore devised experiments with that object in view, but, although some important results were obtained, they were not of the sort sought for. I had expected that the hardening might be accompanied by an increase in the specific gravity, brought about by contraction, but, as will be evident on consideration, this need not necessarily take place, and in fact did not. Experiment V.-The specific gravity of an ox brain reoved from the skull a few hours previously = 1036. After NOTICES OF BOOKS. Cup and Platter, or Notes on Food and its Effects. By G. OVEREND DREWRY, M.D., and H. C. BARTLETT Ph.D., F.C.S. London: Henry King and Co., 1876. "CUP and Platter" is a pleasantly written little volume giving much practical information on the subject of food and its effects on the human system. It is the joint work of Dr. Drewry, a well-known physician, who has specially devoted himself to the study and treatment of diseases of the digestive organs, and Dr. Bartlett, who is equally well known as one of our food analysts. Amongst the more prominent merits of this little work may be reckoned the sound common sense and candid courage with which it exposes many of the mischievous fallacies which at present pass current with regard to the nutritious properties of certain descriptions of food. In the introduction the general properties of food products and the processes of their digestion and assimilation are clearly and succinctly described, and the chapters CHEMICAL NEWS, Oct. 13, 1876. Solid Water. 161 great difficulty in applying any of the systems of units at present in use to a variety of electrical and magnetic measurements. Even the expert scientific calculator is often at a loss when he finds it necessary to convert the results obtained by one system into those of another. Mr. Day's little manual will, we think, be useful both to the beginner and to the practised electrician. The book contains nearly seven hundred examples of exercises relating to every kind of electrical and magnetic measurement. Telegraphic testing, the measurement of magnetic force, resistance of conductors, induction and condensers, and electro-magnetic measurement, coming in for the lion's share of attention. Copious examples relating to liquid and battery resistance, shunts, and derived circuits, heat are preceded by a short preface giving an account of the system of units of measurement adopted by the Units Committee of the British Association, and known to electricians as the c.g.s., or centimetre-gram-second system, and showing how to convert a measurement founded on one system of units into a measurement founded on another. The units employed by practical electricians such as the ohm, the farad, the volt, &c., are also defined and explained. This part of the book might perhaps have been extended with advantage. The answers to the examples are appended, but we think that for the sake of the weaker portion of electrical students a few worked-out problems might have been given. For those who are commencing laboratory practice or who are preparing for actual work in connection with electric telegraphy, Mr. Day's little book will form a necessary complement to the excellent manuals of Culley, Sabine, and which follow give a lucid account of the various descriptions of food in detail, the whole terminating with some excellent practical remarks on the scientific principles of cooking. In the chapter on water the remarks on filtering and filtering media are judicious, and the common error that a filter will last for an indefinitely long period is clearly pointed out. The authors dwell at considerable length on the pernicious effects of " previous sewage contamination" on drinking water, but their remarks on this subject might very well have been supplemented by a warning to their readers of the mischief arising from subsequent sewage gas contamination which, in ninety-nine cases out of a hundred, the water receives after it has found its way into the cistern. It is surely a waste of power and money to compel the different water companies to filter the water supplied bying effects of currents, &c., are also given. The problems them to the public as long as householders are allowed to poison themselves and their families by using cisterns which are in direct communication with the house drain or water-closet through the waste-pipe. The next time that Dr. Drewry meets with a peculiarly puzzling case of derangement of the digestive organs we should advise him to ask his patient to allow him to look at his cistern as well as his tongue. In the following chapter the merits of condensed milk are rightly insisted on, and the authors' remarks on this valuable article of diet will do much to destroy the small amount of prejudice which still lingers among the public with regard to its wholesomeness. Messrs. Drewry and Bartlett, in the chapter on breadstuffs, are strongly in favour of the use of whole meal bread so as to receive the entire nutritive value of the wheat grain. The general public are hardly aware that the rage for white bread leads to the sacrifice of nearly 20 per cent of the flesh-forming constituents of the wheat. The thousand and one so-called farinaceous foods are very properly attacked at the end of this chapter. The pretensions which are contained in the advertisements of manufacturers of this class of foods have long been known by the merest tyro in dietetics to be false and mischievous, but the fallacy has never been so fully exposed as in the present work. In relation to this matter Dr. Harkwicke, the Coroner for West Middlesex, goes so far as to say that most of the deaths of infants under six months old arise from the use of corn flour and other kinds of starchy food. One of the largest firms in the trade coolly assert in their advertisement that when their corn flour is mixed with milk it closely resembles beef and bread! The vegetarian craze reprobated, but we must take exception to one remark in which the authors give it as their opinion that "the cooling and laxative properties possessed by certain descriptions of fruit are those to which the greatest value must be attached." Surely the wholesome properties of the vegetable acids must have been overlooked when this paragraph was written. An eminent physician used to say that if each of his patients were to eat a couple of oranges before breakfast every morning he would lose half his practice. As a rule, we English, especially the middle classes, eat far too little fruit. is In the chapter on stimulants the ingenious action of the different aldehyds, ethers, and alcohols, other than ethylic alcohol, which are found in all new spirits are clearly pointed out. The little work concludes with some capital hints on cookery and kitchen management. We regret to see that Messrs. Drewry and Bartlett have thought proper to introduce the names of several wellknown manufacturers of food products as having furnished them with "characteristic samples" of their manufactures. In a popular book like the present such "honourable mentions" savour too much of the puffing testimonial and ought to have been omitted. Exercises in Electrical and Magnetic Measurement, with ELECTRICAL Students, more especially those who are weak Everett. CORRESPONDENCE. SOLID WATER. To the Editor of the Chemical News. SIR,-Your readers will be amused with the following correspondence which has recently appeared in the Athenæum anent a communication on "Solid Water" which I made to the last meeting of the British Association: "ATHENEUM," September 23, 1876. "Prof. Guthrie's note, 'On Solid Water,' was a description of what he formerly called 'cryohydrates,' aqueous solutions of various salts of such strength that when reduced to certain definite temperatures-all below o° C.the salt and the water solidify together. Surely there is nothing new in the fact of water becoming solid by associating with various compounds in their crystallisation? But of course a scientific man cannot go before the public at the British Association and not be sensational." "September, 1876 "In the Athenæum for September 23 your reporter for the Chemical Section of the late meeting of the British Association, in noticing my communication on solid water as it exists in certain compounds, expresses himself as follows: "Surely there is nothing new in the fact of water becoming solid by associating with various compounds in their crystallisation? But of course a scientific man cannot go before the public at the British Association and not be sensational.' "To the first part of this expression I have only to say that I did not, and do not, pretend to be the discoverer of water of crystallisation as it is ordinarily understood. A great many salts (Epsom salts, blue vitriol, alum, &c.) were known, before your reporter and I were born, to contain water; but others (sal-ammoniac, saltpetre, &c.) |