Chap. I. a beautiful red. Nitrate of lead and sulphate of copper give precipitates approaching to black. M. P. Boullay analyzed some of the ulmates, and found their composition as follows: 1. Ulmate of silver. Composition. Oxide of copper 5 3. Ulmate of copper. Ulmic acid These analyses give different numbers for the atomic weight of ulmic acid. Boullay considers the analysis of ulmate of copper as the most exact. According to it the atomic weight of ulmic acid is 42.61. He subjected ulmic acid itself to analysis, by heating it with oxide of copper, and obtained for the constituents Hydrogen This gives us 42 for the atomic weight of ulmic acid, a number which approaches sufficiently near the number derived from the analysis of ulmate of copper, to give some probability to its being not far from the truth. The reader will observe that the ratios between the atoms of carbon, hydrogen, and oxygen, which constitute gallic acid, are the same as those of ulmic acid. They are both resolvable into 1 atom of water and 2 atoms of carbon. But the atoms in ulmic acid are 64, while those in gallic acid are only 12. Hence the atomic weight of ulmic acid is 5 times greater than that of gallic acid. Dobereiner announced that when gallate of ammonia is exposed to the air it is converted into ulmate of ammonia. But this is not likely, the acid becomes dark coloured, but I find that the atomic weight is scarcely altered.* SECTION XVIII. OF CRAMERIC ACID. Class I Div. II. The Crameria triandra is a plant which vegetates in Peru, History. the root of which is remarkable for its astringent properties, and is said to be employed by the natives of the country where it grows, as a medicine of great efficacy in cases of atonic hæmorrhages. It is said to be brought to London in great quantities for the purpose of giving the requisite colour to artificial imitations of wine. This root attracted the attention of M. Peschier, apothecary at Geneva, who detected in it a new acid, which he has distinguished by the name of crameric acid. He obtained this acid in the following manner: The root (particularly the bark) was boiled with water, and by this means a strong decoction was obtained, which had an astringent taste, and struck a black with sulphate of iron. To free it from the tannin, which it was presumed to contain, the decoction from an ounce of the root was mixed with a solution of 48 grains of gelatine, which occasioned a reddish brown deposite weighing 126 grains. To deprive the decoction of its colouring matter and of its gallic acid, which it still contained, 200 grains of sulphate of iron were added for every ounce of the root employed in making the decoction, and the liquid is then diluted with 7 or 8 pounds of water, and filtered. By this means it is rendered nearly colourless. It is then boiled with a sufficient quantity of chalk to decompose all the sulphate of iron which it still retains, and to saturate the crameric acid present in it. The whole liquid is now passed through the filter and concentrated to the requisite degree. The lime is to be thrown down with carbonate of potash, and the cramerate of potash is precipitated by acetate of lead. The cramerate of lead being properly washed, is decomposed by a current of sulphuretted hydrogen gas. The liquid being filtered and evaporated to the requisite consistency, nothing remains but a solution of crameric acid in water. * See p. 103. Chap. I. Properties. History. Crameric acid thus obtained has a strong acid taste, and leaves upon the tongue a peculiar styptic sensation. It cannot be made to crystallize. It has no action upon the salts of lime and magnesia, but it decomposes all the salts of barytes and strontian, forming two salts with each, a supersalt which is soluble, and a subsalt which is insoluble in water. Cramerate of barytes is not decomposed nor altered by sulphuric acid. So that crameric acid has a stronger affinity for barytes than sulphuric acid has. It throws down the salts of lead white. Cramerate of potash, soda, ammonia, lime, and barytes, throw down the salts of iron yellow. It has no sensible action on the other metalline salts. Cramerate of potash crystallizes in six-sided prisms. Cramerate of soda forms large crystals, having the same shape, and efflorescing when exposed to the air. Cramerate of ammonia yields feather-shaped crystals. All these salts are insoluble in alcohol. They have little taste, and when thrown into a salt of barytes they occasion a precipitate. Such are the properties of crameric acid, pointed out by M. Peschier. They will require to be verified, and I suspect rectified in several points, before the peculiarity of this acid be fully demonstrated, and its characters accurately determined.* SECTION XIX. —OF KINIC ACID. Mr. Deschamps, junior, an apothecary in Lyons, published a method of extracting from yellow Peruvian bark a peculiar salt, to which the physicians of Lyons ascribed the febrifuge properties of that bark. His process was very simple; the bark was macerated in cold water, and the infusion concentrated by evaporation. It was then set aside for some time in an open vessel. The crystals of the salt gradually formed and separated, and they were purified by repeated crystallizations. From 100 parts of the bark about 7 parts of these crystals were obtained.+ This salt was examined by M. Vauquelin, who proved it to be composed of lime united to a peculiar acid, to which he gave the name kinic, borrowed from the term quinquina, applied by the French writers to the bark from which the salt was extracted. Deschamps' salt then is kinate of lime. M. Vauquelin separated the lime from the kinic acid by means of oxalic acid. * See Jour. de Pharmacie, vi. 51. † Au. de Chim, xlviii. 162. MM. Pelletier and Caventon obtained it from the alcoholic tincture of gray cinchona by distilling off the alcohol after having added a sixth part of its weight of water. The liquid remaining in the retort was freed from the fatty matter and the brown resin which had separated during the distillation, and was boiled for some time with a great excess of magnesia and then filtered. Being evaporated nearly to dryness, it assumed the appearance of a magma, which being digested in alcohol left a white salt consisting of kinate of magnesia. It was decomposed by lime, and the kinate of lime in its turn decomposed by means of oxalic acid, and the kinic acid was obtained in crystals by the requisite concentration." They are transparent Class I. Div. II. Kinic acid thus obtained, when pure, has a strong acid taste Properties. without any bitterness. The crystals have a good deal of resemblance to those of tartaric acid. and colourless, and destitute of smell. is 1.637. They are soluble in alcohol. of 48° they dissolve in 24 times their weight of water. When boiled with starch dissolved in water, they convert it into sugar. Distilled with alcohol, they form an ether similar to the tartaric ether of Thenard. Nitric acid converts this acid to the oxalic. Sulphuric acid decomposes it, and gives it at first a fine green colour.+ It combines with bases, and forms a genus of salts called kinates. All these salts are soluble in water. Hence it happens that kinic acid is not capable of throwing down any of the bases when dropped into saline solutions. In this respect it resembles acetic acid. Kinates of lime, barytes, and copper, were analyzed by MM. Composition, Henry and Plisson, who found them composed as follows: These numbers make it probable that the atomic weight of * Ann. de Chim. et de Phys. xv. 304. † Henry and Plisson; Ann. de Chim. et de Phys. xli. 326. The same chemists subjected the acid to an analysis, and found the constituents to be Now the smallest number of atoms that agrees with these proportions and with the atomic weight derived from the analysis of the salts is, But this gives the atomic weight too high. If we abstract an atom of carbon, and consider the acid as composed of History. Properties. we obtain 23 for the atomic weight. This, therefore, is the constitution of this acid that agrees best with the analytical results of Henry and Plisson. SECTION XX.-OF PYROKINIC ACID. This acid was discovered by MM. Pelletier and Caventou about the year 1820. It is obtained by distilling kinic acid. When heat is applied to this acid in a retort it swells up, blackens, and gives out a white acrid smoke. There passes over into the receiver a brown, oily, and very acid liquid, while some crystals make their appearance in the neck of the retort. These crystals were redissolved, and the liquor filtered through moistened cotton to retain the oil. This liquid being slowly evaporated, yielded crystals of pyrokinie acid. Pyrokinic acid crystallizes in tufts composed of diverging needles. It is at first brown, but by repeated crystallizations becomes colourless. Its taste is acid, and it is destitute of smell. It is very soluble both in water and alcohol. It forms soluble salts with potash, soda, ammonia, barytes, and lime. It occasions a * Henry and Plisson; Ann. de Chim, et de Phys. xli. 327. |