26. PREPARATION OF SALICENE. The following is the process recommended for this purpose by M. Peschier. The bark of the willow is to be dried, crushed, boiled for one or two hours in water, and the liquid separated by a cloth and powerful pressure. Subacetate of lead is to be added as long as precipitation occurs; the whole filtered; the clear liquor boiled with enough carbonate of lime to decompose the excess of acetate of lead, saturate the acetic acid, and remove the colour. Being left to settle, the clear liquor is to be decanted, the deposit washed twice or thrice, the washing liquor added to the former, and the whole evaporated to the consistence of an extract. This extract, whilst hot, is to be put into bibulous paper, and pressed for some hours; after which it is to be digested in alcohol of s. g. 0.847, the fluid filtered and concentrated, when it will yield crystallized salicene, very white and pure. Salicene thus obtained, when administered in doses, of from 15 to 18 grains, in the intervals of intermitting fevers, was found perfectly effectual in stopping their progress*. 27. NEW KIND OF INDIGO. The Registro Mercantil of Manilla describes a new kind of indigo lately discovered in that island. This plant has been long known to the natives, especially in the provinces of Caramini and D'Albay; they gave it the name of payanguit or avanguit, and obtain a superb blue colour from it. In 1827 it attracted the attention of Père Mata, one of the members of the Economical Society of Samar. He made many experiments upon it, formed it into cakes, and dyed cotton, linen, and silk goods with it. The colour he obtained was so rich, and so equal to that of indigo, that he sent some of the cakes and the dyed fabrics to the Society, who directed other members residing in the same province to repeat Père Mata's experiments. All obtained most satisfactory results, and they sent many of the cakes, the leaves, and even the living plants, to Manilla. A committee of merchants and chemists was appointed to ascertain, by every kind of trial, whether the colouring matter was identical with that of indigo, and might be introduced as such into the market at the same price. The committee reported in the affirmative on these points, declaring that the payanguit had all the valuable properties of the plant to which it had been compared†. 28. CHARRING OF WOOD AT LOW TEMPERATURES. Mr. Phillips has described the following case of the slow decomposition of wood at low temperatures: Mr. Charles May, chemist, of Ampthill, has sent me some specimens of wood, converted into nearly perfect charcoal at a very low * Ann. de Chim, xliv. p. 418. VOL. I. FEB. 1831. + Bib. Univ. 1830, p. 223. but long-continued heat. The pieces, he informs me, are part of the bottom of a tub which held about 130 gallons, and which had been in use in his laboratory about three years and a half, and almost constantly worked for boiling a weak solution of common salt, generally with an open steam-pipe, and sometimes, though rarely, with a coil the temperature was seldom higher than 216° or 220°, and the vessel was lined with tin, rolled into sheets, about the sixteenth of an inch thick, and nailed to the inside; the joints, however, were not so good as to prevent the liquid from getting between the metal and the wood. Mr. May states also that he had long since remarked, that on making extracts with steam of very moderate pressure, all the apparent effects of burning might be produced, but that he was not prepared to find so complete a carbonization of wood by steam : the vessel was made partly of fir and partly of ash, the former of which was most perfectly reduced to the state of charcoal*. 29. CHANGE Of Colour in the Wood of certain Trees. M. Marcet has experimented upon this point, particularly with the wood of the alder, which, exposed to air, becomes red or brown. The change did not take place if, the instant the wood was cut, it was introduced into a perfect vacuum, or into gases containing no oxygen; but, on the contrary, being put into oxygen, the red colour became more vivid than in the air. If the wood, when cut, was plunged into water, it always reddened, whatever attempts were made to exclude oxygen. Some of the wood, which had acquired a yellow colour, communicated that colour to water, and the water, being evaporated, left a substance having every character of pure tannin. M. Marcet concludes, from his experiments, that the colouration of the alder wood is always due to a degree of oxygenation which the tannin undergoes immediately upon its exposure to the air or oxygent. 30. PRESERVATION OF BLOOD. Sugar refiners and others are often inconvenienced by the difficulty of obtaining blood at the time when it is required for use. M. Toursel has endeavoured, in part, to remove this difficulty, by proposing a method of preserving this agent for some time without injury. It consists in putting the blood into bottles or other vessels with very narrow mouths, and being careful to fill them up to the neck; a layer of oil, to the depth of at least half an inch, is then put upon it to cut off communication with the atmosphere, and the whole is left to itself. M. Toursel states that he has in this manner preserved blood, with all its physical and chemical qualities, from the 1st of December, 1827, to January, 1829. * Phil. Mag. N.S. viii. p. 383. † Bib, Univ. 1830, p. 228. Journ, de Commerce. 31. PRESENCE OF MANGANESE IN THE BLOOD.-(Professor Wurzer, of Marburg.) In some analyses of human blood, according to Engelhart's method, by liquid tests, Prof. W. was led to suspect that, besides the usual results, he had also obtained a small quantity of manganese: not being, however, quite sure of the correctness of his analyses, he was induced to repeat them in the following manner :-The blood, which had been obtained by venesection, on the day before the experiment, was ignited in an open crucible, the incinerated mass oxidized by nitre, and then diluted with water; the residuum was dissolved in muriatic acid, and the iron precipitated from the solution by succinate of ammonia. As the precipitate contained also some phosphate of lime, it was again ignited, and then dissolved in muriatic acid; the phosphate of lime was separated from the solution by alcohol, the excess of the latter expelled by heat, and the iron precipitated by ammonia. By boiling the filtered liquid with carbonate of soda, the manganese was precipitated, and then dissolved in nitric acid and again ignited. In two grammes of the coal was found 0.108 ox. of iron, and 0.034 protox. of manganese*. 32. ON TWO ORES OF TELLURIUM FROM THE ALTAI MOUNTAINS.(M. Rose.) During the journey through Russia and Siberia, which M. Rose, of Berlin, lately made in the company of MM. Humboldt and Ehrenberg, he found two ores of tellurium in the silver mines of Sawodinski, near those of Siranowski, at the river Buchtharma, and as this metal has hitherto been only found in the gold mines of Transylvania and in Norway, this discovery is of the greatest interest. We extract the description of tellurium-silver and tellurium-lead as it is given by M. Rose in Poggendorf's Annalen. He first saw these two ores in the Museum of the town of Barnoul, near the river Ob; besides numerous smaller pieces, there were two large blocks of about a cubic foot each, which, on account of their malleability and the large quantity of silver they contained, were considered to be silver-glass, from which they, however, were found to differ greatly. Tellurium-silver is of granular texture, not crystallized nor cleavable; has much metallic lustre, and its colour is between that of lead and steel it is malleable, though to a less degree than silver-glass; and its specific gravity was found, by two different experiments, to be 8.565 and 8.412. The specimens which were examined by M. Rose were adhering to greenish-grey talc slate, and the ore was mixed with black blende, small quantities of sulphate of iron and of copper, and tellurium-lead, When tellurium-silver was heated before the blowpipe on charcoal, it fused to a black mass, which, on cooling, became covered with *Poggendorff's Ann. der Physik und Chemie. numerous white points and ramifications of metallic silver. It fused also in open and closed vessels; and, when ignited in a retort, tinged the glass with which it was in contact of a yellowish colour: in the open tube it deposited a small quantity of white sublimate, part of which was volatilized by directing the flame upon it, the rest contracting into small globules. It was found to dissolve in nitric acid, particularly when heated, but much less in nitro-muriatic acid, being soon covered by a crust of chloride of silver. If the solution in nitric acid was suffered to cool, small brilliant crystals were deposited, which consisted of the oxides of tellurium and silver, but in a different proportion from what they are in tellurium-silver, for, a short time after their formation, crystallized nitrate of silver was deposited. M. Rose submitted the mineral to the following analysis:-It was dissolved in nitric acid, and after the silver had been precipitated by muriatic acid, the solution was filtered and evaporated; sufficient quantity of muriatic acid was now added until all nitric acid was decomposed, and no smell of chlorine could be perceived. The liquid was then diluted with water and heated, and on the addition of muriatic acid and sulphite of ammonia, a black precipitate was obtained, which consisted of metallic tellurium. The remaining fluid, being filtered, was again submitted to the action of sulphite of ammonia and muriatic acid, and this was repeated as long as a precipitate formed. A current of chlorine gas was then passed through the filtered liquid, in order to oxidize completely the small quantity of iron contained in it, and this was afterwards precipitated by ammonia. By this process M. Rose obtained from 2.833 gramm. of the mineral, 2.348 gr. of chloride of silver, which contain 1.769 gr. of silver, 1.047 gr. of tellurium, and .010 gr. of oxide of iron. By a second analysis, 2.678 gr. of the mineral were found to consist of 1.669 of silver, 0.988 of tellurium, and .050 of iron. According to the first analysis, tellurium-silver consists of And if tellurium-silver be considered as a compound of one atom of silver 62.63, and one of tellurium 37.37, the above results are nearly confirmed*. = The other mineral, tellurium-lead, is, like the former, not crystallized, but cleavable in three directions; the planes of cleavage are not quite even, but seem to be at right angles to one another. Its colour is tin white, almost like antimony, but a little more yellow; * According to Berzelius, the atomic weight of silver is 1351,005, and that of tellurium 806.45, oxygen being 100. it has much metallic lustre, is brittle, and of the hardness of fluor spar: spec. gr. 8.159. It is mixed with small proportions of tellurium-silver, and before the blowpipe on charcoal, fuses to a small button, which gradually diminishes in size so as ultimately to exhibit a small globule of silver, surrounded by a ring of metallic hue, which seems to be formed by the volatilized and subsequently precipitated tellurium-lead. If the flame is directed upon it, it is completely volatilized, the flame becoming at the same time of a blue colour. It fuses also in a retort, and forms a small quantity of white sublimate, which, under the action of strong heat, contracts into small globules. If ignited in an open tube, it fuses and becomes surrounded by a ring of white drops, and at the lower portion of the tube a very dense white sublimate is deposited, which before the flame of the blowpipe contracts into small drops. When powdered, it dissolved in nitric acid with the evolution of red vapours the solution was diluted with water, and the silver contained in it precipitated by muriatic acid; the fluid was then filtered, and the lead precipitated by hydro-sulphuretted ammonia; after twenty-four hours the fluid was again filtered, the sulphuretted tellurium precipitated from it by adding muriatic acid, and the sulphur ultimately separated from the metal by dissolving the sulphuret in nitro-muriatic acid, which precipitated the sulphur. As one analysis only could be made of the mineral, M. Rose refrains from giving any decided opinion on its composition at present; he is, however, inclined to consider it as a compound of 1.28 of silver, 60.35 of lead, and 38.37 of tellurium. 33. BERZELIUS' METHOD OF PREPARING UREA. The following process for obtaining urea is recommended by Berzelius in his recent work on Chemistry, vol. vi., p. 420, of the Swedish original. Recent urine is to be evaporated, and as much of the residuum as possible taken up by alcohol. The alcoholic solution is to be evaporated, and the yellow substance remaining, dissolved in a small quantity of water, and digested with a little animal charcoal, until it is rendered quite colourless. The liquid is to be filtered, heated to 50° Centigr. (122°F.), and as much oxalic acid added as is soluble at that temperature; on cooling, the oxalate of urea is deposited in colourless crystals. If, instead of 122°, the fluid is heated to 212°, the solution of oxalic acid becomes of a brown colour and unpleasant smell; and the crystals, of oxalate of urea, are of a red or reddish-brown colour, but become colourless on adding a small quantity of animal charcoal. On applying gentle heat, so as slowly to evaporate the fluid, the deposition of crystals continues, and their quantity may be further increased by adding a new quantity of oxalic acid as soon as the fluid becomes thick and loses its sour taste. After this process, all the crystals are collected, washed with ice-cold water, and then again dissolved in boiling water with a little animal charcoal; when filtered |