water, the filtered liquid was acidified by muriatic acid and evaporated; it left fifteen grains of residue, which being introduced into a glass tube with a piece of quicklime slightly moistened and heated, gave ammonia sensible not only to test papers, but also by its strong odour. Hence it results, as M. Chevallier has stated, that the natural oxides of iron contain ammonia, and this fact, conjoined with that of Austin, that ammonia is formed by the oxidation of iron in contact with air and water, acquires a certain degree of geological importance *. 10. ATOMIC WEIGHT OF TITANIUM.-(Rose.) M. Rose some time since endeavoured to ascertain the atomic weight of titanium from the analysis of its sulphuret, but finds, as he suspected, that the sulphuret often contains titanic acid, and therefore yields uncertain results. In fact, when chlorine was passed over the heated sulphuret, besides the chlorides of titanium and sulphur, titanic acid always appeared. He has, therefore, resorted to the chloride of titanium as a more definite compound; a mixture of titanic acid and charcoal is heated and chlorine passed over it; the chloride of titanium formed is rectified from off mercury or potassium † several times to remove the excess of chlorine, and is then a clear limpid fluid like water, leaving no trace of chlorine when decomposed by water. If this chloride and water be brought together suddenly, heat is evolved, and the solution is milky; if the chloride is left in a moist atmosphere, the action takes place without the least formation of turbidness. After some time the titanic acid is precipitated by ammonia, carefully added so as not to be in great excess, exposed to a moderate temperature to dissipate the excess, and filtered to separate the titanic acid. The above liquor is then mixed with nitric acid, and the chlorine precipitated from it by a solution of nitrate of silver. The titanic acid and chloride of silver are then weighed and give data to determine the quantity of titanium and chlorine in the original compound. From the mean of many experiments thus made, it would appear that one hundred parts of the compound contain Chlorine Titanium 74.46 71.461 23.539 and as 74.46 chlorine correspond to 16.82 oxygen, that the titanic acid is composed per cent. of Dumas, some time since, endeavoured to ascertain the specific gravity of the vapours of the chloride of titanium, and found it to be 6.836, that of air being 1. This would give the composition of the above compounds as expressed in the second column of figures. The cause of this difference between the results obtained is, at * Ann. de Chimie, xliii., 334. Potassium does not act upon the compound at boiling temperatures. present, unknown, but unfortunately throws doubt upon both processes*. 11. ON THE CRYSTALLIZATION OF GOLD.-(Professor Henslow, of Cambridge.) A small glass-stoppered phial, containing a solution of gold in a mixture of nitric and muriatic acids, had stood long neglected for a considerable time (perhaps four or five years) in a cupboard. Upon accidentally discovering it, I found a portion of the acid had escaped and the gold crystallized. This effect had probably been promoted by a flaw in the phial, which extended through the neck, and a little way down its length. The stopper, in consequence, must have been slightly loosened, and thus allowed more space for the formation of a thin dendritic crystallization of the gold. This was further continued down the inner surface of the phial, and was there sufficiently thick to admit the impression of minute but distinct crystalline facets. A small crystallized lump of gold lay at the bottom of the phial, but I believe this had been originally attached to the rest, and merely fallen by its weight, as I have since observed to be the case in another portion. Around the stopper, and along the flaw, there was a saline concretion, which tasted like sal ammoniac, and as ammonia was kept in the same cupboard, it had probably united with the muriatic acid as it exuded. Upon finding this specimen, I examined some other metallic solutions, and found a similar separation of the metal had taken place, in a phial containing a solution of platina, and in another containing a solution of palladium. In both these cases a thin, interrupted, and dendritic lamina of metal might be seen between the stopper and the neck, but the crystallization had proceeded no further. I unstoppered the phial containing the platina, and the lamina (as might have been expected) immediately disappeared in the form of a slight muddy film. The palladium I still possess. Probably this phenomenon may be of frequent occurrence; but as the separation of the metal does not often extend below the neck of the phial, it may have passed unnoticed. These facts, if multiplied, may perhaps serve to throw some light upon the mode in which the dendritic laminæ of native gold, silver, &c., are formed in rockst. It would have been satisfactory to know whether, in the case described by Professor Henslow, any lard, wax, or lubricating matter had been originally applied to the stopper of the phials, which could have caused or promoted the effect of reduction. The Professor has not before met with any cases of reduction in the crystalline form of gold from solution in acid. These, however, are not uncommon. We have specimens of gold finely crystallized, by gradual reduction and deposition, from an ethereal solution of its chloride; and both gold and silver, and also other metals, may be reduced Mag. Nat. Hist. i., 146. Annalen der Physik, xv., 145. from these solutions in acid, and crystallized, by leaving pieces of charcoal, phosphorus, &c., in them.-Ed. 12. SALICINE-Its power as a FEBRIFUGE.-(Leroux.) A very important Memoir by M. Leroux, which was presented to the Academy of Sciences, has been most favourably reported upon by MM. Gay Lussac and Majendie. It relates to nothing less than the discovery of a principle in indigenous plants which may replace quinia and cinchonia as medical remedies. Being aware that the willow had been employed advantageously as a bitter and febrifuge, M. Leroux sought in it for some active principle, and ultimately sent two preparations to the Academy, one called salicine, the other sulphate of salicine. He at first thought the new principle was a vegeto-alkali, but when afterwards in Paris, he convinced himself that it had no power of neutralizing acids, did not combine with them, was rendered uncrystallizable by them, contained no nitrogen, and was not a vegeto-alkali. The sulphate was a mistake. Salicine is in the form of very fine nacreous white crystals, very soluble in water and alcohol, but not in ether; it is very bitter, and partakes of the odour of willow bark. In order to obtain it, three pounds of the bark of the willow (salix helix), dried and pulverized, is to be boiled in fifteen pounds of water, with four ounces of carbonate of potash, for an hour; it is to be filtered, and, when cold, two pounds of solution of sub-acetate of lead added: when settled, it is to be filtered, treated with sulphuric acid, the rest of the lead precipitated by sulphuretted hydrogen, the excess of acid neutralized by carbonate of lime, again filtered, the liquid concentrated and saturated by dilute sulphuric acid, then boiled with animal charcoal to remove colour, filtered hot, crystallized repeatedly, and dried without access of light. About one ounce of salicine will be obtained in the large way; probably twice the quantity would result, for great loss is occasioned by the above numerous operations. It may be preserved in well-closed bottles, and does not attract moisture. As to the medicinal powers of this substance, M. Majendie states, that his own experience of its effects in intermitting fevers is favourable, and that he has seen three doses, of six grains each, stop a fever. He quotes the experiments of MM. Miquel, Husson, Bally, Girardin, Cognon, &c., at the hospitals and elsewhere, in its favour they all agree in its anti-febrile power, and in stating that from twenty-four to thirty grains of salicine will arrest the return of the fever, whatever may be its kind. This is nearly the same as the dose of the sulphate of quinia. In concluding, the commissioners state, that M. Leroux has discovered in the willow (salix helix), a crystallizable principle which approaches sulphate of quinia in its anti-febrile power, and that this discovery is, without contradiction, one of the most VOL. I. Ост. 1830. N important that has been made for many years in pharmaceutical chemistry*. 13. PREPARATION AND COMPOSITION OF MALIC ACID. This curious vegetable acid has been obtained pure and crystallized by M. Liebeg, and carefully analysed, for the purpose of setting the discordant results of different chemists at rest. The expressed juice of the ripe fruit of the mountain ash was boiled with animal charcoal, which had previously been purified by muriatic acid; and a certain quantity of potash added, but so as to leave a great excess of acid; the whole evaporated till thick as syrup, then mixed with five or six times its volume of spirit of wine, and the clear, vinous liquor, after separation from the mucilaginous matter, distilled. The thick viscid residue of the distillation was again acted upon by alcohol, which entirely did away with the mucous state. Being again distilled, the residue was diluted with much water, precipitated by acetate of lead, and the malate of lead obtained, decomposed in water by sulphuretted hydrogen. The addition of potash and treatment by alcohol has for its object the separation of tartaric acid and tartrate of potash, which occurs in the original juice, and which otherwise would have given a mixture of tartaric acid with the malic. As directed, the malic acid can contain only citric acid, or traces of tartaric acid; when concentrated, therefore, ammonia is to be added in quantity insufficient to neutralize the liquor; alcohol, equal in volume to the liquid, is to be added also, and the whole allowed to cool, when quadrangular crystals of the acid malate of ammonia will be obtained, the salt being very little soluble in alcohol, even though diluted. These dissolved in water, precipitated by acetate of lead, and the precipitate decomposed by sulphuretted hydrogen, yield pure malic acid; which will be found to crystallize by evaporation in the air, forming, first, acicular crystals, and ultimately a solid crystalline mass. A crystallized malate of zinc was then formed, resembling in properties that described by M. Braconnet. By a heat of 212° it loses ten per cent. of water, without change of form; at 248° it lost other ten per cent., then becoming a white coherent powder. By analysis, the salt gave 46.734 malic acid, 32.711 oxide of zinc, 20.555 water, the oxygen of the oxide, water and acid being as 1:34. Hence the equivalent of malic acid is 57.3, hydrogen being unity. The malate of silver is anhydrous at 212°, and composed of 66.975 malic acid, 33.026 oxide of silver per cent., which gives the equivalent number of malic acid as 57.2. When the dry salt is decomposed by heat, it blackens only for an instant, and yields carbonic oxide gas, which burns like alcohol, and contains no empyreumatic matter. * Ann. de Chimie, xliii., 440. The acid malate of ammonia was then decomposed in the manner adopted by MM. Liebeg and Woehler, with the hippuric acid*. It gave azote and carbonic acid in the proportion of 1 : 8, indicating four atoms of carbon in the acid. The hydrogen was determined by burning the dry malate of zinc with oxide of copper, and collecting the water by chloride of calcium. The results came out as 4 atoms carbon, 24; 2 hydrogen, 2; 4 oxygen, 32; 58: but as this was too high, as compared to the conclusions respecting the equivalent number, and as it was the same with the composition of dry citric acid, excess of hydrogen was suspected; and as a trace of water in the salt used would account for this excess, other experiments were made with the anhydrous malate of silver. This salt gave little more than one atom of oxygen, and the composition of malic acid may therefore be considered as follows: : 24 1 32 57† Equivalent number 14. ULMIN, OR ULMIC ACID, AND AZULMIC ACID. The following points relative to the history of ulmin are abstracted from a thesis by M. P. Boullay on this subject. This substance derives its importance from the numerous circumstances which give rise to it, and the daily conversion of numerous vegetable matters, especially those in wood, into it. Its existence in vegetable earth, in manure, and in the sap of plants, shews the important part which it performs, and it is probably the most valuable compost known. It occurs in enormous quantities in brown earth, turf, &c., and Holland probably owes the superiority of its agricultural productions to the quantity which it naturally possesses. M. Boullay has considered it as an acid, and gave it a corresponding name, because of its power of combining with bases. It was first found by Vauquelin in an exudation from the elm tree; M. Braconnot formed it artificially. It is produced in the distillation of wood in soot, and may be formed by the action of sulphuric and muriatic acids upon many vegetable substances. Ulmic acid differs from the substances produced by the action of air or oxygenizing bodies, on extracts, tannin, gallic acid, or gallates, both by its colour and solubility in alcohol. It is more probable, from the properties of the resulting substance, that when gallic acid or the gallate of ammonia is exposed to air, a new substance, not sufficiently examined, is produced. The composition of ulmic acid is the same as that of dry gallic acid, but it has a much feebler saturating power; its equivalent number is to that of gallic acid as 5: 1. It has been analysed by * Quart. Jour. of Science, vol. vii. p. 424. + Ann. de Chim. xliii. 259. |