the surface covered for the greater part with its epidermis; and 3, the sort which generally occurs mixed with Lora or Crown bark, in middling fine quills. The latter was carefully selected from an original package of Loxa Cinchona :

The following was the method employed to separate the alkaloids:-1000 grains of the finely powdered bark was extracted with a mixture of 30 grains pure concentrated sulphuric acid, and 8 ounces water, in the water-bath, the extract removed, and the residue treated again with a mixture of 10 grains sulphuric acid and 8 ounces water. The extracts united, clarified by settling, poured off from the sediment, and digested at a moderate temperature with six drachms, fresh prepared, finely powdered hydrate of lime, until entirely decomposed. The edulcorated, dried and powdered lime precipitate was then boiled repeatedly with the requisite quantity of alcohol of 0.863 sp. gr., to which some pure animal charcoal had been added, to extract the alkaloid which was thus obtained on evaporating the alcohol in a nearly pure state, and after drying in thewater-bath, was weighed. When the barks abound in resin, the alkaloid, especially if it be quinine, frequently contains, by this process, some resin; this cannot be detected, from the action of the residue. In this case the alkali was separated from the resin by dissolving it in very dilute acetic acid, and precipitating with a solution of ammonia, then dried and weighed. The separation of the cinchonine and quinine was effected by allowing the greater part of the

* Which gave rise to the excessively bitter taste of the bark; a proof that this can never be depended on as a test of the goodness of bark.

As no mention of this substance is made in the last edition (1842) of Dr. Pereira's work, we have extracted the following short account from Berzelius's 'Lehrbuch,' vol. vii. p. 403 :

"This peculiar crystalline substance was first discovered by M. Winckler in Cinchona nova, when extracting the bark with æther, in one of Robiquet's displacement apparatus. The æther is distilled off, and the residue treated with alcohol of 0-863 sp. gr., in which it is very soluble. The greater part of the alcohol is driven off, and a small quantity of ammonia added, to fix the kinovic acid, and then precipitated with water. A milky-white powder is deposited, which is the kinova bitter. It cannot be sublimed, does not combine with bases or with acids, although soluble in hydrochloric acid, as well as in caustic potash, when boiled with them. Buchner, jun. subsequently proved the identity of this substance with Smilacine, with which it agrees in its physical properties as well as in its composition. It contains 62.56 Carbon, 8.70 Hydrogen, 28.73 Oxygen."

+ Small quantities of quinine are best detected by dissolving from a quarter to -half a grain of the extracted alkali in a small white test-tube, in an excess of very dilute sulphuric acid. If only a trace of quinine be present the peculiar blue opakeness renders it perceptible, even though the alkali is still impure, and the solution of the bisulphate more or less coloured yellow on that account.

cinchonine to crystallize out of the alcoholic solution of the alkalies extracted in the above manner, and treating the residue with æther, in which cinchonine is very slightly soluble. For the sake of comparison, equal quantities of several kinds of cinchona bark were extracted completely with alcohol of 0.863 sp. gr., the tinctures treated with hydrate of lime, until a solution of the perchloride of iron no longer afforded any reaction, the filtrated alcoholic solution which had been previously decolorized with animal charcoal, evaporated in the water-bath, the residue treated with very dilute acetic acid, in order to remove the resin and kinova bitter, and the alkali precipitated with ammonia from the previously filtrated solution of the acetate.

In most cases, especially with barks rich in alkali, the resultagreed exceedingly well with that obtained by extracting with acidulated water, &c.; in barks containing but little alkali the treatment with alcohol, &c. has decidedly the preference. Besides, this process has the advantage, that the amount of kinova bitter may be determined, at least approximately, at the same time; as the bitter is dissolved, on treating the residue, previously extracted with acid, with æther, still in combination, it is true, with a yellow colouring substance from which it is difficult to separate, while the resin remains undissolved. In the examination of the Huamalies barks this method was employed to determine the amount of kinova bitter; if it is wished to determine this accurately, it is preferable to extract the finely powdered bark immediately with absolute æther, to evaporate the solution, treat the residue with strong alcohol, decolorize the solution with charcoal, and to leave the filtrated solution to spontaneous evaporation.

When but a small quantity of bark is at hand a mixture of about 60 grains of the powdered bark, with as much hydrate of lime, and 30 grains animal charcoal, is extracted with the requisite quantity of alcohol, and the residue remaining after evaporation of the filtrated alcoholic extract treated with acetic acid, &c. By this method any loss of alkali is possibly avoided.

II. CINCHONA CARTHAGENA, S. FLAVA DURA; Carthagena
Hard Cinchona. China flava dura, Germ.

This kind of cinchona belongs to those barks which are poor in alkalies. From a collection of 40 samples of good cinchona 30 agreed well with one another, and belong to the above bark. Some of the kinds not belonging here afforded only cinchonine, but agreed in their physical characters more with Cinchona rubiginosa than the true Cinchona flava fibrosa, which, according to Winckler's experience, likewise contains cinchonine only, is very similar, especially the flat pieces, to the Cinchona regia, but seldom occurs in commerce. 94 ounces of the hard yellow cinchona afforded:

Cinchonine, 78 gr.

Quinine, 14 gr.

This bark contains, moreover, a considerable quantity of kinova bitter, of which a portion was separated by concentration and precipitating with hydrochloric acid from the solution filtered from the lime precipitate.

Between this bark and the Cinchona flava fibrosa stands that kind of cinchona which was previously described by Winckler as Cusco cinchona. In its physical properties it bears much resemblance to the Cinchona rubiginosa and Cinchona flava fibrosa, but is easily distinguished when seen in mass by its grayish brown colour. It differs from the Cinchona carthagena dura by the softer consistency of the substance (the rete mucosum and cortical layers). In thin quills, which are however of rare occurrence, it resembles, to deception, the true Cusco bark.

This bark is very rich in alkali; Winckler formerly obtained it from a well-known wholesale druggist under the name of Cusco china, but subsequently from a different source as Cinchona flava Cusco, which latter name he considers most proper, from its containing, beside cinchonine and quinine, a considerable quantity of a third alkaloid agreeing with that to be subsequently described under Cusco bark.

Thirty-three ounces of bark afforded 260 grs. of raw alkali, which by re-dissolving in boiling alcohol was separated into cinchonine, quinine (almost in equal proportions), and a small quantity of the new alkali. This bark, which is scarcely known, belongs, therefore, to the best kinds, and approaches nearest in amount of alkali to Cinchona rubra. In this latter bark a considerable quantity of kinova bitter was also found.

[To be continued.]

CHEMICAL PREPARATIONS.

Preparation of finely divided Calomel.

SOUBEIRAN proposes the following method as much better than that with steam, being very much easier to execute and equally efficacious as regards the beauty of the preparation. The calomel is heated in an earthen tube in a furnace, and a current of air is directed uninterruptedly into the tube by means of a small ventilator. This sweeps away, as it were, the vapours of calomel, and in a straight tube will carry them a distance of 60 feet, to avoid which the end of the recipient enters into water, by which means the calomel is moistened and falls down.-Compt. Rend. 1842, Mai, p. 665.

Righini has found that by the long-continued action of steam upon finely-powdered calomel a small portion of corrosive sublimate is formed. Journ. de Chim. Med., Avril 1842, p. 190.

Preparation of Hyperchloric Acid.

In the preparation of this acid from hyperchlorate of potassa, the sulphuric acid employed is generally diluted with water. Nativelle has shown that this is very objectionable, and proposes the following method:-500 parts of finely pulverized hyperchlorate of potassa are put into a retort, and 1000 parts of sulphuric acid of 66° (sp. gr. 1.848)

diluted with 100 parts of distilled water are added. A receiver is adjusted without any lute of paper or other organic matter; if any be used it should be of asbestus. As hyperchloric acid is volatilized at 140°, it is better not to let the mixture boil; by this means sulphuric acid is prevented from passing over. If the residue in the retort becomes colourless and no more drops pass over although the temperature is high, then the operation is finished, In this way 300 parts of impure acid are obtained, sp. gr. 1.455. If the distillation has been conducted too rapidly it contains sulphuric acid, and has a higher specific gravity. In order to free it from chlorine and sulphuric acid, it is shaken with a small excess of sulphate of silver. The filtered solution is mixed with newly precipitated carbonate of baryta until all the sulphuric acid is saturated and only a little hyperchlorate of baryta is formed. The filtered acid, containing silver and baryta, is then distilled at a gentle heat, and the water which passes over first received by itself until it has an acid reaction. The distillation may be conducted to dryness. The acid thus obtained is pure, colourless and transparent. Its specific weight lies between 1-117 and 1·824; it is oily like sulphuric acid. From 500 parts of hyperchlorate Nativelle obtained 150 parts of pure acid. Journ. de Pharm. 1842, i. p. 498.

Pure Sulphuric Acid.

Jacquelin prepares pure sulphuric acid for accurate analyses and as a toxicological test, by first purifying the acid with sulphur; he then adds a small quantity of solution of chlorine to it, and boils it for some minutes. The acid is then perfectly free from sulphurous, nitric and hydrochloric acids. He considers sulphate of protoxide of iron to be the best test for detecting traces of the oxides of nitrogen in sulphuric acid. He takes at least 50 grammes, about 750 grains of sulphuric acid, and pours on to it 7 grains of distilled water, allows it to cool, and then adds 10 drops of the sulphate, stirring the mixture to prevent much heat being evolved.-Ibid., Mai 1842.

Preparation of Chloride of Zinc according to Righini.

Dissolve 80 grm. of pure crystallized chloride of barium, and 98.6 crystallized sulphate of zinc, each in 750 grm. distilled water; pour both solutions together into a flask, and heat for a time in the water-bath; strain and evaporate to 60 grm.; strain again through a filter covered with animal charcoal mixed with some powder of chloride of barium, and then evaporate until the liquid left to itself solidifies in white crystalline flocks, which are dried and preserved in closely-stoppered bottles.-Gaz. des Hôpitaux, t. iv. No. 86.

Preparation of pure Potassa and Soda.

The best method of preparing caustic baryta is, as is well known, by decomposing sulphuret of barium with oxide of copper. The

easy preparation of it has induced Dr. Schubert to propose the following plan for preparing pure potassa or soda. He dissolves crystals of neutral sulphate of potassa, or effloresced sulphate of soda, in a very concentrated solution of caustic baryta, until chloride of barium causes no precipitate in a filtered portion; he then adds carefully a dilute solution of baryta, and then, if necessary, dilute sulphate, until neither baryta nor sulphuric acid is contained in the solution. If there is excess of baryta it will fall as carbonate on evaporating the solution, but this induces the necessity of re-solution and evaporation, by which the alkalies absorb carbonic acid.Journ, für Prakt. Chem., xxvi. 117.

Louvier's Unguentum contra Tineam.

This salve consists of 6 parts soda, 40 parts slacked lime, and 1200 auxungia. After the hair has been cut, the crusts softened, and all the places cleansed with soap and water, this salve is rubbed in daily, care always being taken that the parts are kept clean. Subsequently a powder, consisting of 15 parts caustic lime and 1 part charcoal, is strewed among the hairs, which so destroys the roots that the hair may be removed with the pincers without pain. When this has been done the embrocations are continued until the skin has acquired its usual colour.―Journ, de Pharm. 1842, p. 65.

Employment of Sulphuret of Iron in Cutaneous Diseases.

Sulphuret of iron has lately been used by Cazonave in cutaneous diseases, in the form of extremely fine powder suspended in 60 parts of Syrupus saponariæ.

CHEMISTRY APPLIED TO ARTS AND MANUFACTURES.

Theory of Saponification. By Prof. LIEBIG.

WHAT was known of the nature of saponification, previous to the commencement of the present century, amounted to nothing, excepting the important discovery, by Scheele, of the sugar of fats, now called the hydrated oxide of glyceryle. Chevreul began, in 1813, a series of investigations on soaps, which have not only thrown a clear light on this portion of chemistry, but have also led the way to the most brilliant discoveries in the whole province of organic chemistry. We are indebted to him for the present predominating principle in all organic researches, viz. to subject a body to a series of changes, and to ground its composition on their ascertained connexion.

Chevreul proved that all fats comprehended under the terms grease, oil and tallow, consist of three materials united in the most varied proportions, one of which, oleine, at common temperatures, and