hydrogen in the one tube as we obtained oxygen in the other.

Let us now direct our attention to the next typical hydride, namely, hydride of nitrogen or ammonia. The combination of hydrogen with nitrogen to form ammonia can be effected by indirect methods only, but it may be shown by a variety of processes, with which I will not trouble you, that these two gases always unite with each other in the ratic of one volume of nitrogen to three volumes of hydrogen. But nitrogen is found to be exactly 14 times heavier than hydrogen; and, accordingly, taking the specific gravity of hydrogen as unity, the specific gravity of nitrogen will be 14; or, calling the weight of a litre of hydrogen one crith, the weight of a litre of nitrogen will be 14 criths. Hence we have in ammonia three volumes of hydrogen combined with one volume of nitrogen, or 3 parts by weight of hydrogen combined with 14 parts by weight of nitrogen. Further, when one volume of nitrogen combines with three volumes of hydrogen to form ammonia, the four volumes become condensed into exactly two volumes. I cannot show you this conversion of four volumes of mixed nitrogen and hydrogen into two volumes of combined nitrogen and hydrogen, but the reverse experiment is of very easy performance. Thus, if we submit ammonia gas to the action of the electric spark, it undergoes decomposition into its elementary constituents, as you perceive. We have here two volumes of ammonia gas, which, by the continued action of the electric spark is decomposed into its constituent nitrogen and hydrogen, and the two volumes of ammonia become gradually increased into four volumes of hydrogen and nitrogen, mixed in the proportion of three volumes of the former to one volume of the latter gas. But in this case, as in the previous two, the information afforded by a determination of the specific gravity of ammonia renders a direct experiment of any kind unnecessary. We find that the weight of two litres of ammonia gas, for instance, is identical with the conjoint weight of one litre of nitrogen and of three litres of hydrogen; so that while from two litres of hydrochloric acid gas we can extract one litre of hydrogen, and from two litres of steam we can extract two litres of hydrogen, so from two litres of ammonia we can extract three litres of hydrogen, in addition to the one litre of chlorine, oxygen, and nitrogen respectively. Or from equal volumes of chloride of hydrogen, oxide of hydrogen, and nitride of hydrogen, we may obtain one volume of hydrogen, two volumes of hydrogen, and three volumes of hydrogen respectively, in addition, in each case, to the one volume of chlorine, the one volume of oxygen, and the one volume of nitrogen, as illustrated by these models.

unites with one volume of chlorine, and leaves the extra quarter volume of chlorine unacted upon. In the same way, if we mix together one volume of chlorine and one volume and a quarter of hydrogen, the one volume of chlorine will unite with exactly one volume of hydrogen to form hydrochloric acid, leaving the extra quarter volume of hydrogen unacted upon. Try the experiment how we please, we come to the same conclusion, that chlorine and hydrogen gases will unite only in the proportion of volume to volume. But chlorine is exactly 355 times heavier than hydrogen; or, taking the specific gravity of hydrogen as unity, the specific gravity of chlorine will be 355; or, if we call the weight of a litre of hydrogen one crith, the weight of a litre of chlorine will be 35'5 criths. Accordingly, in hydrochloric acid gas we have one volume of hydrogen united with one volume of chlorine, or 1 part by weight of hydrogen united with 35'5 parts by weight of chlorine. Moreover, when hydrogen and chlorine gases unite with one another to form hydrochloric acid gas, they undergo no alteration what ever in bulk. If we take, for instance, a litre of hydrogen and a litre of chlorine, we obtain exactly two litres of hydrochloric acid. This persistence in bulk is capable of being shown by direct experiment, but may be inferred with equal certainty by merely taking the specific gravity of hydrochloric acid gas. The weight of two litres of hydrochloric acid gas, for instance, proving to be identical with the weight of one litre of chlorine, plus that of one litre of hydrogen, it is evident that mixed hydrogen and chlorine on becoming combined hydrogen and chlorine occupy one and the same bulk before and after combination. Turning our attention next to the combination of hydrogen with oxygen, we find that when oxygen and hydrogen gases unite with one another to form water, it is always in the proportion of one volume of oxygen to two volumes of hydrogen; and, conversely, when we decompose water electrolytically into its constituent gases, we find that for every single volume of oxygen liberated at the one pole, we have two volumes of hydrogen liberated at the other. Experiment has proved over and over again that just as chlorine and hydrogen will unite with one another only in the proportion of volume to volume, oxygen and hydrogen will unite with one another only in the proportion of one volume of the former to two volumes of the latter gas. But oxygen is found to be exactly 16 times heavier than hydrogen; or, taking the specific gravity of hydrogen as unity, the specific gravity of oxygen will be 16; or, calling the weight of a litre of hydrogen one crith, the weight of a litre of oxygen will be 16 criths. Hence, in water we have two volumes of hydrogen united with one volume of oxygen, or 2 parts by weight of hydrogen united with 16 parts by weight of oxygen. When, however, two volumes of hydrogen unite with one volume of oxygen, they do not form three volumes, but only two volumes of gaseous water or steam. That is to say, the three volumes of mixed hydrogen and oxygen form only two volumes of combined hydrogen and oxygen. This condensation is capable of being shown by direct experiment, but really we do not require any such experiment, since the result may be demonstrated with equal certainty by observing the specific gravity of steam. We find, for instance, that the weight of two litres of steam is identical with the conjoint weight of one litre of oxygen and of two litres of hydrogen; so that while from two litres of hydrochloric M. GERNEZ presented a note "On Sources of Error in Exacid gas we can extract only one litre of hydrogen in periments with Saturated Solutions." A paper by this addition to the one litre of chlorine; from the same bulk gentleman, which we have recently published (vol. xi., of steam or gaseous water we can extract two volumes of pp. 250-289), states that the one cause of crystallisation hydrogen in addition to the one volume of oxygen. in supersaturated solutions is the introduction of a solid In the experiment taking place on the table of the electro-particle of the substance in solution. The object of this lytic decomposition of water, you see we have roughly, note is to explain that the air is full of solid particles of for the single volume of oxygen, a double volume of salts which are deposited on every substance in a labohydrogen; and by performing the experiment with certain ratory; and if iron filings seem to provoke crystallisation precautions, we should obtain exactly twice as much in a solution of sulphate of soda, or if a layer of oil on

Hydrochloric acid gas.

H CI

Two volumes of
Steam.

Ammonia.

H

=

H
HO

H

HN

(To be continued.)

ACADEMY OF SCIENCES.

July 10.

the surface of the solution does not prevent crystallisation, it is because small particles of sulphate of soda are present with both these substances. It is the same alum which the author says he has often found in dust.

M. Roux presented a memoir " On Water Tanks for the Navy." This paper is of some importance, for the author discusses the question, What is the best and safest material for the construction of water tanks for ships? Galvanised iron, it seems, has been employed in the French Navy, but this is condemned by the author who finds zinc in the water kept in such tanks, and in such quantities that he considers the liquid unfit for domestic uses. M. Roux has also made experiments on the preservation of water in tanks that have been ungalvanised by removing the coating of zinc with hydrochloric acid, which we may suppose to represent plain iron vessels. In one of these he placed distilled water, in another water issuing from the green sand and containing some chloride of sodium, and in a third river water containing more chloride of sodium. He found the largest proportion of oxide of iron with the distilled and river water. In conclusion the author recommends for the Imperial Navy water tanks tinned inside and galvanised outside, but he does not say how such tanks are to be made.

MM. P. and E. Depouilly read a note " On the Manufacture of Phthalic and Chloroxynaphthalic Acids." In a paper we published vol. xi., p. 242, the authors described the production of benzoic from phthalic acid, but they did not publish their method of producing the latter acid. We are now told that by treating naphthaline in the cold with alkaline chlorates and hydrochloric acid a large proportion of chlorine is fixed on the naphthaline in one operation, and considerable amounts of the bichlorides of naphthaline and chloro-naphthaline are obtained with but little of the protochloride. The last, an oily body, is easily got rid of by pressure. The mixture of the bichlorides is then treated with nitric acid, by which the bichloride of naphthaline is converted into phthalic acid, and the bichloride of chloro-naphthaline is transformed into chloride of chloroxynaphthyle. From such a mixture the phthalic acid is removed by boiling water, and will then serve for the process described in the previous paper. The chloride of chloroxynaphthyle, which remains undissolved, is now treated with caustic alkali in solution, and is thus converted into an alkaline chloroxynaphthalate. From the solution of this mineral acids precipitate the chloroxynaphthalic acid. This acid is purified by converting it into a soda salt from a neutral solution, of which alum will precipitate all the coloured impurities. The filtered solution now precipitated by a mineral acid deposits pure chloroxynaphtalic acid as a pale yellow crystalline powder. The salts of this acid are of considerable interest: the potash soda and ammonia salts are of a deep red colour, and give blood-red solutions. The lime salt, less soluble, is deposited from a boiling solution in silky crystals of a golden yellow colour. The baryta salt is of a beautiful orange colour; the alumina salt is madder coloured; the copper and mercury salts are bright red; zinc and cadmium give reddish brown salts; nickel and cobalt pomegranate coloured compounds; lead a nasturtium coloured salt. The aniline salt is of a beautiful red colour; the rosaniline salt is green, giving with water a solution of a beautiful cerise colour. All these salts seem applicable to industrial and artistic purposes. The acid itself dyes wood without a mordant a very deep red, and with other colours of course gives varied shades.

M. Deschamps presented a communication "On Absinthe." We have several times of late years had occasion to refer to communications on this subject-a matter of very little importance to Englishmen-and we may dismiss this paper very briefly. Many French writers have ascribed the most pernicious consequences to the habit of drinking this most disagreeable of liqueurs, and

many have supposed that wormwood is a most dangerous and insidious poison. M. Deschamps, however, believes that all the bad effects may be ascribed to the alcohol.

M. Boudin presented a note relating two instances in which the corpses of individuale killed by lightning seemed to be charged with electricity like Leyden jars, for in each instance people going to the assistance of the deceased received violent shocks.

NOTICES OF BOOKS.

Annales de Chimie et de Physique. May, 1865. THIS journal opens with a long article by M. J. G. Wilm, entitled "Researches on Thallium." We have much respect for M. Wilm, many of whose contributions to science have been communicated to our readers, but we believe we have a right to complain of some injustice done to us in this article. The author does occasionally refer to the CHEMICAL NEWS, but we must suppose that he is not a regular reader of this journal, or it is clear that his obvious bias in favour of M. Lamy's claim for priority in the discovery of the metallic nature of thallium could hardly have led him to make the misstatements here made. We refer to M. Wilm's account of the history of thallium; and as the CHEMICAL NEWS is much read on the Continent, we must, in justice to ourselves, but at the risk of wearying some of our English readers, refer once more, and we hope for the last time, to this dispute. After giving accurately enough the early history of the discovery, and stating that M. Lamy exhibited a small piece of the metal to the Société Impériale, &c., of Lille on May 16, 1862, M. Wilm proceeds :-"M. Lamy, however, having heard that Mr. Crookes had exhibited thallium in the International Exhibition, immediately proceeded to London; he was anxious, in fact, to compare the two products so oppositely described. On the 6th of June, 1862, he showed to several members of the Chemical Jury, more especially to MM. Hofmann, Balard, and Crookes himself, an ingot of thallium weighing twelve grammes, and communicated to them verbally the principal properties and mode of preparing the metal; he assured himself also that the body exhibited by Mr. Crookes was not thallium, and that until then the metallic character of the element had never been recognised in England." In opposition to this we need only repeat what we stated in answer to M. Dumas (CHEMICAL NEWS, vol. vii., p. 13), that our case was deposited in the Exhibition some days before it opened on May 1, and in that case were several grains of metallic thallium; and along with it was a card on which M. Lamy, if he had known English, might have read the following:-" Thallium, a New METALLIC Element, discovered by means of Spectrum Analysis;" and beside this was another card on which was written:"Chemical Reactions of Thallium, by which it is distinguished from every other known element. It appears to have the character of A HEAVY METAL," &c., &c. After suspecting it for some time, we had, indeed, definitely recognised the metallic nature of the element in the previous year; but to decide our claim to priority of publication, it is only necessary to appeal to the above documentary evidence, and, to use the words of M. Wilm, "tranche le debat."

After that we need only say that the author adopts M. Dumas' classification of thallium with the alkaline metals; appropriates freely our own published researches; quotes the papers of MM. Lamy, Kuhlmann, jun., Werther, Böettger, and others; and states that his own attention has been principally directed to the chlorides, bromides, and iodides of thallium, and to the salts of the peroxide, all of which are, perhaps, the best known compounds of the metal.

The other papers in this number of the Annales are two memoirs by MM. H. St. Claire Deville, Caron, and Troost, re-published from the Comptes Rendus, "On the Artificial

The Retrospect of Medicine: being a Half-Yearly Journal
containing a Retrospective View of every Discovery and
Practical Improvement in the Medical Sciences. Edited
by W. BRAITHWAITE, M.D., &c., &c., and JAMES BRAITH-in
WAITE, M.D. Vol. li., January to June, 1865. London:
Simpkin, Marshal, and Co. 1865.

We need only notice the punctual appearance of this
journal, containing, as usual, a large amount of
selected matter, carefully condensed-matter from which
we borrow a few short notices for our "Miscellanea."

649 M. Morgans, Brendon Hills, Somersetshire, "Imwell-provements in converting cast-iron or pig-iron into wrought iron or steel, and in machinery employed therein.". March 8, 1865.

Transmutation of Metals.-I recollect the para-on a clean piece of paper, it was transferred to a small graph referred to by Mr. Irvine going the round of the papers, but I could never ascertain that there was any truth in it. It is, however, an undoubted fact that about twelve or eighteen months ago bismuth rose in price from 25. 9d. to 24s. per pound; but I believe the company said to have been formed for transmuting it into silver to be a myth. Perhaps the following facts may clear up the mystery. The chief supply of bismuth is derived from the Royal Saxon mines at Schneeberg, which are also worked for cobalt and nickel. The lode in which these metals occur crosses in one part of its course a thin lode of silver. At the point of contact a small percentage of this metal is of course obtained; but for some time past it has been so small as not to be worth extracting, and the three metals have been sent together to this country. When the cobalt and nickel have been extracted, whatever trace of silver there may be remains in the bismuth. Possibly some one may have accidentally met with a specimen unusually rich in silver, and thence concluded that the extraction of the precious metal would turn out a profitable speculation. The Schneeberg mines are now only partially worked. A cheaper substitute for cobalt blue has been discovered, and supplies of nickel being obtained from other sources, the prices of both metals have declined. The importation of washed ore obtained from these mines used to be about 700,000 pounds per annum, but it has now fallen to about 50,000 pounds. The supply of bismuth is almost exclusively obtained from Schneeberg, and this falling off in the supply would almost of itself be sufficient to account for the rise in price of the metal. This, I think, satisfactorily disposes of the "Transmutation of Metals Company (Limited);"the but I hope in a future communication to show that believers in a sort of modified alchemy are not by any means rare even in the nineteenth century.- Richard B. Prosser, 25, Southampton Buildings, W.C.-Notes and Queries.

[We happen to know that a professed transmutor, a German, had an office in Leadenhall-street two years ago, and for a time found dupes.-ED. C. N.]

:

Arsenic Eating. Dr. Maclagan, of Edinburgh, on a visit to Styria in the spring of this year, obtained conclusive evidence of the existence of this practice, and has published in the Edinburgh Medical Journal a circumstantial account of what he saw. We quote one case, in which it will be seen no jugglery could have been practised :"Mathias Schober, a healthy-looking, fresh-complexioned, fairly muscular young man, of the age of 26 years, and about five feet nine inches in h ight, a native of Liegist, and employed as a house servant there, said he had taken Hüttereich for about a year and a half-not, however, white arsenic, but the yellow arsenic, or orpiment, of which he took a specimen from his pocket and showed it to me. Of this I retained a piece for chemical investigation. He informed me that he took the arsenic in order to keep strong, though he had never suffered from ill health. He said he had never experienced any bad effects, even when he first began using it; that he had at first taken rather less than a grain every fortnight; that he now took it twice a week; and that on omitting to take it for any longer period he experienced a longing for it, which was relieved by a repetition of the usual dose. His reason for taking the orpiment instead of the white arsenic was, that it was more easily procured; but having professed himself quite indifferent whether it were arsenious acid or the sulphuret, Dr. Knappe produced a paper containing the former (of which I also kept a sample), and having asked him to choose out a piece such as he was in the habit of taking, it was weighed, and found to be nearly five grains. We had no finer weight than one grain; but the piece of arsenic was much over four, though less than five. Dr. Knappe, having carefully ground this to powder

piece of plain white bread, about as large as a man's thumb-nail, and this the doctor put into his mouth. Schober chewed it and swallowed it, and then swallowed another portion of bread the same size immediately after. This was at 9:30 a.m. He stayed with us a few minutes, but he had to return to his work, promising, however, to come back in a short while. This he did at 11.30, two hours after, and made water in my presence to the amount of what I estimated at twenty-eight ounces, into a vessel previously carefully cleaned, and the urine was put into bottles thoroughly washed by myself. Unfortunately, in the hurry of my departure, in trying to pack these bottles into my hat-box, I broke one, and thus lost part of the urine. Since my arrival in this country I subjected the contents of the two remaining bottles to chemical analysis, adopting the distillation process of Dr. Taylor as the most convenient way of separating arsenic from the organic matters of the urine. For this purpose the urine was carefully evaporated to dryness in a clean retort. The nearly dry residue was covered with strong hydrochloric acid, and distilled into a well-cooled receiver. The product, amounting to about half an ounce, was a clear, feebly pinkish fluid, thirty minims of which, when treated both by Reinsch's and Marsh's process, gave very characteristic arsenical deposits. Schober also came the following day to see me, having taken no more arsenic since the dose which he had swallowed before me twenty-six hours previously. I again secured some urine which he passed in my presence, and this, when chemically examined as above, also yielded arsenic freely." Dr. Maclagan adds"It is evident that the confirmation of the existence of practice of arsenic-eating must lead us to modify some of the opinions that are entertained with regard to the influence of habit on the action of poisons. It has long been notorious that, by habit, the human body may be brought to bear with impunity doses of organic poisons, such as opium, which, to those unaccustomed to them, would certainly prove fatal; but it has hitherto been limits, habit appears to exercise no influence on the action considered by toxicologists that, except within very narrow of mineral poisons.' (Taylor On Poisons,' p. 89.) Though the experiment of M. Flandin, by which he proved that he could bring dogs to bear fifteen grains of arsenious acid in powder in twenty-four hours, without injury to their appetite or health, and the practice of administering arsenic to horses, have long been known as pointing rather in the contrary direction, this has been supposed to be due to some peculiarity in the constitution of the lower animals. The facts which have been ascertained with regard to the Styrian arsenic-eaters, and which the above observations confirm, entitle us to maintain that the modifying effect of habit is not confined to organic poisons, but extends to those of mineral nature-at all events, to

arsenic."

Carbolic Acid is strongly recommended to dentists cleaning out carious teeth previous to stopping them. It is said, also, to be an effectual cure for toothache.

ANSWERS TO CORRESPONDENTS.

In publishing letters from our Correspondents we do not thereby adopt the views of the writers. Our intention to give both sides of a question will frequently oblige us to publish opinions with which we do not agree.

All Editorial Communications are to be addressed to the EDITOR, and Advertisements and Business Communications to the PUBLISHER, at the Office, 1, Wine Office Court, Fleet Street, London, E.C. Private letters for the Editor must be so marked.

A correspondent asks for information on the use of cod's roes or peas in the manufacture of albumen for print works.

probably is never exactly the same in any two operations.
D. A.-The percentage on the care taken in the manufacture, and