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NEWS

May I be permitted to quote an additional instance? In the oil obtained from the seeds of the croton tiglium chemists have discovered a peculiar acid, crotonic acid, which has been lately observed also among the derivatives of mustard.

This substance, consisting of carbon, hydrogen, and oxygen, is convertible by oxidation into another acid, succinic acid, a beautiful crystalline body, which is more frequently obtained by submitting the familiar resin amber to the action of oxidising agents.

Succinic acid, when combined with an additional atom of oxygen, gives rise to the formation of malic acid, a crystalline acid largely present in the juice of apples and rhubarb-the substance, indeed, to which the acid reaction of these juices is chiefly due. On cutting an apple or a piece of rhubarb and pressing the cut surface against a piece of blue litmus paper it is immediately reddened. But malic acid also may be still further oxidised, the product being one of the most familiar vegetal acids, tartaric acid. This acid is one of the compounds existing largely in the juice of grapes. When a grape is squeezed on a piece of blue litmus paper, the latter is reddened wherever it comes in contact with the grape juice.

The molecules of all these acids contain the same number of carbon atoms and also the same number of hydrogen atoms, the difference in their composition consisting entirely in the number of oxygen atoms which are present, as obvious by reference to the diagram.

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Succinic acid
Malic acid

Tartaric acid

Increment of Oxygen.

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CHO2
CHO
CHO,+ 0
CHO,+2O = CHO
CHO,+3O=CHO
CHO,+4O = CH.O.

In this diagram an unknown acid CHO, figures between crotonic and succinic acids. This substance has not yet been obtained, but the experience of the gradual assimilation of oxygen in other series permits us to forecast the existence of this compound. Though not yet actually prepared, I have not hesitated to introduce it into the list of bodies derived from crotonic acid by simple oxidation.

The three examples which we have studied unmistakably show us that oxygen is capable of combining with other groups of elements so as to give rise to new compounds: that this combination takes place stepwise, atom by atom; that the fundamental properties of the original compound remain more or less unaltered in the new compound of greater complexity, and that the amount of oxygen thus, so to say, assimilated, is in no way dependent on the greater or less complexity of composition of the original compound. In the first case we had the simplest of all possible compounds, hydrochloric acid consisting of one atom of hydrogen and one of chlorine; in the second case we started with a compound containing two atoms of carbon and four of hydrogen, altogether six atoms, while in the case of crotonic acid not less than four atoms of carbon, six of hydrogen, and two of oxygen, altogether twelve atoms, were involved.

An endless variety of similar examples might be quoted for the purpose of illustrating the generality of the inferences we have drawn, but I will, with your permission, assume that I have established my point.

troducing at the same time other elements into the com-
position of the compound. Let us endeavour to illustrate
this point by examples; we could not, perhaps, quote a
better case than that of benzol, the substance which is the
starting-point of the manufacture of aniline, the source of
the beautiful colours so much in request at the present
time. Benzol consists of carbon and hydrogen. No one
has as yet succeeded in uniting this substance with
nitrogen alone. Nothing, on the other hand, is easier than
to combine benzol simultaneously with nitrogen and
hydrogen. The very transition of benzol into aniline
involves the assimilation by the benzol molecule of one
atom of nitrogen and one atom of hydrogen. Again,
aniline is capable of fixing a second atom of nitrogen, but
not without assimilating also a second atom of hydrogen.
The compound thus produced is a beautiful crystalline
body called phenylene-diamine, which is likely to receive
some interesting applications in the manufacture of brown
dyes. To this compound, again, additional atoms of
nitrogen and hydrogen may be joined, a fourth substance,
as yet without application, picryl-triamine, being formed.
The following diagram, in which, again, the simplest com-
pound (benzol) is placed at the top of the list, shows how
these several substances are related to each other :-
Increment of Nitrogen.
C&H6

Benzol
Aniline

Phenylene-diamine
Picryl-triamine .

CH+HN=C,H,N
CH+ 2HNCH.N2
CH+3HNCH,N2

Let me give you another and even simpler series in Hydride of ethyl, like illustration of the same point. benzol, refuses to combine with nitrogen, but it also receives into its molecule one atom of nitrogen and one atom of hydrogen, the well-known substance ethylamine, which has the greatest analogy with ammonia, being formed. This, by a repetition of the same transaction, is converted into ethylene-diamine, an oily base of great causticity; while a third repetition of the process produces a compound, vinyl-triamine, the existence of which is not yet fully established. The analogy between the first and the second series is obvious by a comparison of the formula. Increment of Nitrogen.

Hydride of ethyl
Ethylamine
Ethylene-diamine
Vinyltriamine

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C2H6
C2H6 +
C2H+ 2HN
CH+3HN C2H2N2

=

We entirely refrain from examining into the particular processes, varying to a very considerable extent, by which these transformations are accomplished, the only point, which we have an interest in establishing here, being that nitrogen, when it joins a compound, joins not alone, but in company with hydrogen. In this respect, then, nitrogen essentially differs from oxygen, which we saw combining with bodies, atom by atom, without involving the introduction of other materials.

Can we explain this strange difference in the behaviour of oxygen and nitrogen? Before endeavouring to answer this question, let us examine in what manner carbon atoms are received into the molecules of bodies, whether like oxygen atoms they are capable of joining directly, or like nitrogen atoms they are accepted only when presenting themselves Investigation of a special in company with other atoms. We have, in the next place, to examine whether subcase appears best fitted to supply the desired information. stances are capable of combining with nitrogen, exactly Among the endless number of carbon compounds, we as we have just seen them unite with oxygen. Remem- could not possibly select a simpler one than marsh-gas. bering as we do that nitrogen is rather marked by the This transparent, colourless inflammable gas, as every one absence of salient combining powers, we are not surprised knows, escapes from the fissures of the great coal measures to learn that all attempts hitherto made with the view of and accumulates in the galleries of ill-ventilated coaladding nitrogen directly to other bodies have entirely mines, frequently giving rise to the explosions so much failed. But even indirectly by availing ourselves of dreaded and deplored. It is also often developed from roundabout ways, by calling to our aid the multitude of stagnant pools and swamps, in general from marshy lands, Marsh-gas consists of carbon and reactions which modern chemistry has brought to light, whence its name. nitrogen cannot be added to other substances without in-hydrogen. Is this substance convertible into a compound

which contains a larger amount of carbon? By a series of processes far too numerous and complicated to admit of being discussed this evening, marsh-gas may be converted into hydride of ethyl, a substance of very similar properties, and which the members of the Royal Institution have frequently seen prepared by a simpler method discovered by Dr. Frankland-viz., the action of zinc-ethyl upon water. Hydride of ethyl contains one atom of carbon more than marsh-gas; but with this carbon atom two hydrogen atoms have been simultaneously conferred upon the marsh-gas molecule. On submitting hydride of ethyl to a similar series of transformations, we convert it by the addition of another carbon atom into hydride of propyl, but not without fixing again two atoms of hydrogen.

The same processes may be repeated again and again, hydride of propyl being converted in its turn into hydride of butyl, and hydride of butyl into hydride of amyl. We arrive in this manner at a series of bodies very similar in their properties, each of them differing from the previous one by the accession of one carbon atom invariably linked with two atoms of hydrogen. Many members of this series are found amongst the products of the distillation of coal; others, especially those richer in carbon, existing in the American oils, which are now being so much used for lighting and other purposes.

The composition of these several bodies may be exhibited in the following diagram :—

Again, we may take another compound as point of departure. Formic acid is a body long since discovered to be secreted by the ant. By adding an atom of carbon and two of hydrogen to this acid we arrive at acetic acid, which we have already met with this evening as one of the products of the oxidation of olefiant gas. By the successive accumulation, within the molecule of this acid, of similar quantities of carbon and hydrogen, a long series of acids is formed, including some of the most interesting compounds with which the chemist has to deal; butyric acid, contained in butter; valeric, the active constituent of the valerian root; caproic and caprylic, obtained from goat's fat; œnanthylic, from castor oil; pelargonic, the odoriferous principle of pelargonium roseum; rutic, the product of oxidation of oil of rue; palmitic, contained in palm oil and in spermaceti; margaric and stearic, constituents of the majority of animal fats; cerotic and melissic acids, lastly occurring in the several waxes. Increment of Carbon.

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Increment of Carbon.

Caprylic

Hydro-carbons.

Pelargonic,,

Marsh gas

. CH

Rutic

Hydride of ethyl

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CH10

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CH2O2+ 11CH, CH2O2+12CH2

CH12

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=

C6H14

Benic

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C-H16

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C8H18

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Hydride of propyl

Hydride of butyl

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CH2CH2 CH+ 3CH2 CH. + 4CH, CHA+SCH2 CH+6CH, CH+7CH2

=

=

But we may illustrate the law which regulates the increment of carbon by starting from another foundation. Instead of building on marsh-gas, we make use of the oxide of marsh-gas, methylic alcohol. This compound, by the successive addition of one atom of carbon and two of hydrogen, produces a series of alcohols which may be regarded as the oxides of the corresponding marsh-gas analogues. The first compound thus obtained is ethylic alcohol, ordinary spirits of wine; the second, propylic alcohol, generated in the fermentation of the grape-skin residue of the manufacture of wine; the third, butylic alcohol, formed by the fermentation of the molasses of beetroot sugar; the fourth, amylic alcohol, or potato oil, obtained as a residue in the manufacture of spirit from the starch of potatoes. Caproic, œnanthylic, and caprylic alcohols are further terms of the series, which rises, not without considerable gaps, to terms containing as many as eighteen, twenty-seven, and even thirty atoms of carbon, which are found respectively in palmitic, cerotic, and melissic alcohols-the first, a product of the decomposition of spermaceti; the last two, derived from ordinary bee's wax and Chinese wax.

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CH2O2+13CH, CH
CH2O3 + 14CH,
CH2O2+ 15CH2 CH32
CH,O, + rŠCH,
CH2O2+17CH,

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=

C18H30

C17H34O C18H3802

2CH, – C, HO,

CH2O2+29CH2 = C„H2O2

The action of the acids just examined upon the groups of alcohols previously studied gives rise, as is well known, to the class of bodies called compound ethers. On arranging some of the numerous bodies belonging to this group into a series in which the carbon rises atom by atom, we find, in exact accordance with our former observations, that the accession of one atom of carbon involves the simultaneous introduction of two atoms of hydrogen :Increment of Carbon. Compound Ethers. C2HO2

Formate of methyl. Formate of ethyl Acetate of ethyl Butyrate of methyl . Butyrate of ethyl Acetate of amyl

.

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CHO + CH=CH. O, C,H,O,+2CH=CHO, C2HO2+3CH2=C2H12O2 CHO,+4CH=CHO, . CHO+5CH=C.HO,

All these substances present more or less general interest. The powerful, and in some cases almost repulsive odours which the compound ethers possess may be tamed down by dilution, so as to render these substances useful, and, indeed, extensively applied, substitutes for natural essences. Formate of methyl, the simplest of all compound ethers, like the next term, formate of ethyl, has received some applications in the flavouring of inferior varieties of rum. Acetate of ethyl, familiar to every one as acetic ether, is used for "improving" certain wines; the butyrate of methyl and ethyl, substances which undiluted possess an almost overwhelming, and by no means attractive, odour, exhale, when dissolved in an appropriate amount of spirits of wine, the finest perfume of the pineapple; acetate of amyl, lastly, the final term of our series,

exhibits the peculiar aroma of the jargonelle pear in so high a degree that it is now extensively manufactured to flavour the well-known pear drops of our confectioners. I must not, however, dilate too much on the odoriferous qualities of the compound ethers; here, indeed, we are concerned with these substances only in so far as they afford additional evidence in favour of our speculations respecting the growth of carbon in a series of carbon compounds.

One more illustration, and we shall have done with this part of our inquiry. In a lecture delivered some time ago in this theatre, I had the honour of submitting to the members of the Royal Institution a brief account of Mauve and Magenta, the remarkable coal derived colouring matters which have sprung from the happy union of industry and science in our times. May I be permitted once more to call your attention for a moment to the group of tinctorial ammonias? Aniline red, or rosaniline, as it is called by chemists, is convertible by certain processes into beautiful violet, and even blue colouring matters. This conversion invariably involves addition of carbon to the molecule of rosaniline. By its conversion into certain varieties of violet, the red fixes six atoms of carbon; by its transition into certain bluish shades, not less than fifteen atoms of carbon are assimilated. In what manner does this increment of carbon affect the amount of hydrogen? Inspection of the diagram teaches us that aniline violet contains 12 = 2 x 6 atoms of hydrogen more than aniline red, and that the transition of red into blue is attended by an accession of as many as 30 = 2 × 15 atoms of hydrogen.

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ACADEMY OF SCIENCES.
September 25.

M. BOUSSINGAULT presented a memoir "On the Functions of Leaves." Having shown before that pure carbonic oxide is not decomposed by leaves, he now details experiments which prove that the same gas is never decomposed when diluted by some inert gas as hydrogen. This inertness of carbonic oxide with regard to the green parts of leaves the author takes as a corroboration of the opinion which supposes that leaves simultaneously decompose water and carbonic acid, the latter being transformed into carbonic oxide: CO2,HÓ CO,H,O,,CO,H expressing the relation in which carbon is associated with the elements of water in cellulose, starch, and sugar-that is, in the principles elaborated by leaves, and whose composition is represented by carbon and water. Further, the author states that the decomposition of water by leaves is no longer an hypothesis. He has established the fact by the analysis of plants grown in an utterly sterile soil under the influence of carbonic acid and water alone. He then proceeds to show that there is a limit to the decomposition of carbonic acid by leaves. A square centimetre of leaves exposed to sunlight for nine hours decomposes 1'14 cc. of carbonic acid. A perfectly dry leaf loses its power of decomposing carbonic acid, and that power can never be restored. The vegetable cell, therefore, offers a striking contrast to the animal cell, since dried infusoria are restored to vitality by moisture. The leaf once dried, its vitality is destroyed for ever. There is nothing like latent existence.

Under the influence of this agent, the granules seem to contract, separate as flocculi, and fall to the bottom of the vessel. A curious fact pointed out by the author is, that, on crystallising a solution of iodide of potassium containing a slight excess of iodine, the whole of the latter is taken out by the crystals, the mother-liquor containing

none.

M. Gal presented a note entitled "Researches on the Cyanic Ethers." By passing a current of dry hydrochloric acid into perfectly dry cyanic ether (Wurtz's), the author obtained a simple combination of the two bodies. It is a colourless liquid at ordinary temperatures, has a piquant smell, fumes slightly in contact with moist air, and slowly becomes a white crystalline mass. On adding a few drops of water to the liquid, the temperature soon begins to rise, and carbonic acid is evolved. If only a very small quantity of water is added, and the tube is cooled, the mixture becomes solid. Treated with more water the solid mass dissolves, and the solution gives a yellow precipitate with bichloride of platinum. Analysis shows that this precipitate is a double chloride of platinum and ethylammonium. The above mentioned solid compound is therefore chloride of ethylammonium, C,H,N,HCl. Hydrobromic acid gives a corresponding compound. Both this and the hydrochloric compound with cyanic ether decompose when heated in sealed tubes; hydrochloric and hydrobromic acids escape when the tubes are broken, and a crystalline body remains behind, which is cyanuric ether.

M. Payen made another communication" On Iodide of Potassium," in which he showed that the starch granules swollen under the influence of the neutral iodide are coloured an intense violet by a slight excess of iodine.

The author next studied the action of the hydracids on the cyanic ether obtained by M. Cloez by the reaction chloride of cyanogen on ethylate of soda. This body, although isomeric with the ether employed in the above experiments, differs from it in all other respects. With dry hydrochloric acid it furnishes chloride of ethyl and cyanuric acid, and with hydrobromic acid undergoes a corresponding splitting up.

The author regards this latter as pure cyanic ether, and writes its formula

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The properties of the former (obtained by the reaction of sulphovinate and cyanate of potash) seem to show that it is a derivative of ammonia, and its composition may be represented by the formula— C2O

NCH..

NOTICES OF BOOKS.

Journal für Praktische Chemie. No. 13. 1865. IT is sufficient to say of this number that it contains no communication of interest of which some account has not already been given in the CHEMICAL NEWS.

Chemisches Central Blatt. No. 43. 1865. THE numbers of this periodical of late have been destitute of novelties of interest; but in this number we notice a communication by Professor Städeler, entitled "A Contribution to the Knowledge of Aniline Colours," in which he shows that it is possible to produce true aniline dyes; that is, dyes from aniline without intervention of toluidine. We shall shortly give an account of the author's experiments.

Death of Professor Beaumert.—We regret to announce the recent decease of the above eminent chemist, whose name will be remembered in connection with the early history of ozone. The experiments by which he attempted to prove that ozone was an oxide of hydrogen higher than the binoxide, although not generally accepted, showed great ingenuity, combined with much philosophical

acumen.

NOTICES OF PATENTS.

NEWS

GRANTS OF PROVISIONAL PROTECTION FOR French serpents. A solution of pernitrate of mercury is

SIX MONTHS.

Communicated by Mr. VAUGHAN, PATENT AGENT, 54, Chancery Lane, W.C. 1884. G. Nimmo, Jersey, New Jersey, U.S.A., "Improvements in the manufacture of pots and crucibles wherein metals and other materials may be heated or melted."-Petition recorded July 19, 1865.

2008. J. W. Perkins, Norfolk Street, Strand, "Improvements in the treatment of hydrocarbon or paraffine oils." August 3, 1865.

2307. W. Unwin, Sheffield, "Improvements in the manufacture of iron."-September 9, 1865. INVENTION PROTECTED BY THE DEPOSIT OF A COMPLETE SPECIFICATION,

2436. T. V. Lee, Macclesfield, Cheshire, "Improvements in preparing turf for fire-lights and fuel, and for machinery to be employed therein."-Recorded September 23, 1865.

NOTICES TO Proceed.

1349. H. A. Bonneville, Rue du Mont Thabor, Paris, "Improvements in hydrometers for ascertaining the strength of spirits and the specific gravity of fluids."-A communication from C. A. Valsou, Rue de Ponthieu, Paris. -Petition recorded May 15, 1865.

MISCELLANEOUS.

Money Grants of the British Association.-The following are the only grants made by the British Association for chemical investigations:-Mr. Fairley, polycyanides of organic radicles, 20l.; Dr. Matthiessen, cast iron (renewed), 50l. Those made for geological observations (which involve, we imagine, agreeable trips on the part of the observers) amount to 415., and those for zoology, botany, and physiology amount to 3401. The amount granted for Kew Observatory is only 600l., a miserable sum when the work done there is taken into account. Some of the grants, we think, might reasonably have been withheld, and the money better applied in improving the salaries of the Kew officials.

Pharaoh's Serpents.—The following account of the curious experiment mentioned by our Paris correspondent last week is contributed to the Pharmaceutical Journal by Mr. C. H. Wood :-"A very curious toy is now being sold in Paris, under the name of Pharoah's Serpent. As this toy really constitutes an interesting chemical experiment, perhaps an account of it may prove interesting to your readers. It consists of a little cone of tinfoil, containing a white powder, about an inch in height, and resembling a pastille. This cone is to be lighted at its apex, when there immediately begins issuing from it a thick, serpent-like coil, which continues twisting and increasing in length to an almost incredible extent. The quantity of matter thus produced is truly marvellous, especially as the coil which so exudes is solid, and may be handled, although, of course, it is extremely light and somewhat fragile. Having a little of the white powder, with which the cones are filled, placed at my disposal by a friend, I submitted it to analysis, and found it to consist of sulphocyanide of mercury. This salt, when heated to a temperature below redness, undergoes decomposition, swelling or growing in size in a most remarkable manner, and producing a mixture of mellon (a compound of carbon and nitrogen), with a little sulphide of mercury. The resulting mass often assumes a most fantastic shape, and is sufficiently coherent to retain its form; it presents a yellow colour on the exterior, but is black within. The serpent' shape, of course, results from the salt being burnt in a cone of tinfoil. Both the mercurous and mercuric sulphocyanides decompose in the same manner; but the mercuric salt,

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containing more sulphocyanogen, seems capable of furnishing a larger quantity of mellon, and is the one used in the readily precipitated by sulphocyanide of ammonium, and the mercuric sulphocyanide may be easily so prepared. It is best to use the mercurial solution as strong as possible, and to keep it in excess throughout the precipitation. Solution of perchloride of mercury is not so easily precipitated as the pernitrate, probably owing to the solubility of the mercuric sulphocyanide in the chlorides. Perhaps I nium, suitable for the above purpose, may be very easily may be excused for adding that sulphocyanide of aminoand economically prepared as follows:-One volume of bisulphide of carbon, four volumes of liq. ammon. fort., and four volumes of methylated spirit are put into a large bottle, and the mixture frequently shaken. In the course of one or two hours, the sulphide of carbon will have entirely dissolved in the ammoniacal liquid, forming a deep red solution. When this result is attained, the liquid is boiled until the red colour disappears, and is replaced by light yellow. The solution is then evaporated at a very gentle heat (about 80° or 90° F.) until it crystallises, or just to dryness. The product is sulphocyanide of ammonium, sufficiently pure for the above purpose. One recrystallisation from alcohol will render it quite white. One ounce of bisulphide of carbon yields by this process exactly one ounce of sulphocyanide of ammonium."

Industries of Birmingham and its Neighbour. hood. Following the example set at Newcastle, some Birmingham gentlemen are about to publish a series of reports on their local industries. The volume, it is said, will include reports prepared by gentlemen whose abilities and experience in their various departments will give the work an official and authoritative value as a récord of the history and progress of the multifarious trades of Birmingham and the district. The manufacture of brassfoundry, buttons, boilers, bedsteads (iron and brass), cables, chandeliers, coins, medals, and dies; electro-plate, gas fittings, glass (crown, flint, and stained), guns and pistols, hinges, japan ware, jewellery, nails (cut and wrought), needles, nuts and bolts, optical instruments, paper, papier maché, pins and needles, railway carriages, rules, saddlery, saws, steel pens, surgical instruments, tin plate goods, wire, wire working, wood screws, and many more of the infinitely varied trades will be fully described. The South Staffordshire district will be reported on by a local committee appointed for the purpose, and the report will include an account of the coalfield, and its probable extent and duration, by Mr. J. Beete Jukes, the statistics of the iron and coal trades, and a history and description of the manufactures of the principal towns of the "Black Country;" forming a complete and detailed account of the vast resources and varied products of the Midland hardware towns. Some account of the North Staffordshire iron trade, of the products of Stourbridge, Kidderminster, Redditch, and Coventry, will also be included in the work, which will show the enormous extent, varieties, and excellence of the products of the district described.

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Note on Zirconium, by Dr. T. L. PHIPSON. AFTER having found that magnesium heated to fusion in close vessels with the acids silicic, boracic, and carbonic, liberated the radicals of these acids, I thought that zirconium might be prepared in the same manner; for many facts show a great analogy between this body and silicium. In 1863 I had not enough of pure zirconia to make the experiments in a conclusive manner. Since then I have prepared a certain quantity with the zirconian syenite of Norway. I obtain thus a zirconia containing about 2 per cent. of yttria. On repeating the experiment I found that oxide of zirconium is reduced as easily as silicic acid or boracic acid, under the influence of magnesium. The reduction takes place at the moment the magnesium begins to melt, and zirconium is obtained in form of a velvety black powder. Dilute hydrochloric acid dissolves the whole of the magnesia formed.

In this manner one can easily obtain large quantities of amorphous zirconium. I have also reduced titanic acid. But whilst silicium and titanium (in some of my experiments) can form gases on combining with hydrogen, boron and zirconium do not. The five bodies carbon, boron, zirconium, silicium, and titanium, form evidently a group of very similar elements.-Cosmos.

What are the Source, Annual Field, and Characteristics of the so-called Volcanic Ammonia ?* by Mr. W. D. HOWARD.

THERE is no difficulty in giving the requested information as to the source and characteristics of the ammonia; the annual yield is not so easily arrived at. However, whatever information I can give is very much at the service of the Pharmaceutical Conference.

To begin, then, with the source. Almost any chemical handbook will show that the proprietor of those marvellous geological riddles, the boracic acid lagoons of Tuscany, does not succeed in preparing from the waters of the lagoons his acid in a state of purity. In commerce it always appears containing from 13 to 20 per cent. of impurities, besides adherent moisture. Conspicuous among these stand various double salts of ammonia, notably the double sulphate of magnesia and ammonia, and from these the ammonia is derived by a very simple process-viz., the double decomposition which ensues when the soda ash is added to the rough boracic acid in the manufacture of borax. The carbonate of ammonia escapes with the carbonic acid and steam, and is easily condensed by a suitable apparatus. After a second purification it takes the form which is tolerably familiar to the members of the Conference.

To illustrate the subject, I give analyses made of an average of the greater part of the boracic acid imported in each of the years 1858 to 1863 inclusive, representing 9307 casks. As every one of the casks was sampled, and special pains were taken that the annual average should not belie its name, the analyses may be fairly considered to represent the actual yield of the lagoons in those years. Further to ensure accuracy, larger quantities than customary were used in the analyses, as much as 500 grains being generally employed, and some of the more minute constituents being determined on twice that quantity. The average of 1862, which re

* Read at the meeting of the Pharmaceutical Conference. VOL .XII. No. 306.-OCTOBER 13, 1865.

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The only characteristic of the ammonia derived from this source that I am aware of is its perfect purity and freedom from all those minute traces of evil-smelling compounds with which both that made from gas liquor and from bones is so liable to be tainted.

The annual yield of the lagoons is, as I previously stated, an almost impossible problem. Doubtless the amount of ammonia arriving in this country in the boracic acid is a very small amount in comparison with that which is yearly run away in the mother liquors. Nor do I think that there would be a profit on collecting it, as the price it would fetch in this market would hardly do more than cover the expenses of transit.

On the Action of Light upon Sulphide of Lead, and its bearing upon the Preservation of Paintings in Picture Galleries, by Dr. D. S. PRICE.t

THE author's attention was directed to this subject by observing that in the cases in the South Kensington Museum, which are painted with white lead, that substances which emitted sulphurous vapours did not cause a darkening of the surface of the case, excepting where it was protected from the direct influence of light. A number of experiments was then tried as to the action of light upon sulphide of lead produced by the action of sulphuretted hydrogen upon lead paint. A board painted white with white lead was exposed for several hours to the action of sulphuretted hydrogen, until the surface had acquired a uniform brown colour. Plates of glass of different colours were then placed upon the painted surface, one portion being at the same time covered with an opaque medium, and another left entirely exposed. The board was then placed facing the light. The glasses employed were red, blue, yellow (silver), violet, and

Read at the meeting of the British Association.

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