(1607) Urea is accompanied in urine by small quantities of two other crystallizable principles, which have received the names of kreatine and kreatinine. The alkaline properties of the first are extremely feeble. In order to prepare these bodies from urine, the liquid is to be neutralized by lime, and a solution of chloride of calcium added, so long as it produces a precipitate. The filtered liquid is to be evaporated by a water heat, until the salts crystallize on cooling; the mother-liquor is then to be decanted, and mixed with one-twentieth of its bulk of a saturated solution of zincic chloride. In the course of three or four days a deposit of rounded yellow crystalline grains of chloride of zinc and kreatinine, mixed with crystals of kreatine, occurs. These crystalline masses must be washed with cold water, and then dissolved in boiling water, after which hydrated oxide of lead is to be added, till the liquid is distinctly alkaline. The hydrochloric acid and zinc are thus precipitated from the hot liquid, in the form of hydrated oxide of zinc and oxychloride of lead. The filtered solution is digested with animal charcoal, in order to remove adhering colouring matter, and, on evaporating the solution, mixed crystals of kreatine and kreatinine are deposited. Hot alcohol dissolves the kreatinine, and during evaporation yields it in crystals. The undissolved portion is kreatine. If, instead of employing fresh urine for the extraction of kreatine and kreatinine, it be taken after putrefaction has commenced, the kreatine, according to Liebig, will have disappeared, whilst the kreatinine remains unchanged. Both kreatine and kreatinine were originally discovered among the constituents of the fluids contained in the muscular tissue. There can be little doubt but that, like urea, they are products of disintegration of the muscular tissue, and that they are destined either for ulterior change in the economy, or for immediate rejection as excrementitious matter; and this view is strengthened by the fact that the proportion of kreatine is greater in the muscles of animals killed in the chase than in the same animals killed otherwise.

Kreatine (Є,H,N ̧ЄH ̧Ð=131+18).—Kreatine is present in the juice of the flesh in very small proportion, whence the name, from κplaç, flesh, given to it by its discoverer, Chevreul. A pound of flesh yields on an average, according to Gregory, about five grains of kreatine; the quantity, however, varies in the flesh of different animals. The flesh of the common fowl was found by

Gregory to contain more kreatine than that of any animal upon which his experiments were made; but cod fish is its cheapest source: 10,000 parts of fresh cod furnish from 9 to 17 parts of kreatine, whilst the same weight of fowl furnishes 32 parts : and Neubauer found in ox flesh on the average 20 parts. The best process consists in chopping up raw cod finely, mixing it with an equal weight of water, and expressing the liquid. This liquid is next heated sufficiently to coagulate the albumin, taking care to avoid ebullition, after which it is filtered. Baryta water is then added cautiously, so long as it occasions a precipitate; the liquid is again filtered, to separate baric phosphate; and the filtrate, on being evaporated to a very small bulk, yields crystals of nearly pure kreatine. It may be rendered quite pure by a second crystallization.

Kreatine crystallizes in colourless, transparent, brilliant, oblique prisms, which, when heated to 212°, become opaque, and lose their water of crystallization. Kreatine is sparingly soluble in cold water, of which it requires 75 times its weight for solution it is freely dissolved by boiling water. Alcohol, when cold, scarcely dissolves it; it is insoluble in ether. The aqueous solution has a weak, bitterish taste. Although kreatine is neutral to test papers, it forms definite compounds with some of the acids. Kreatine hydrochlorate (E,H,N,,,HCl) forms colourless, welldefined crystals, which are soluble in water. It may be prepared by mixing solutions of equivalent quantities of hydrochloric acid and kreatine, and evaporating in vacuo, or by a temperature not exceeding 90° (32° C.). The sulphate (2 Є,H,N,2,H2SO) may e obtained in a similar manner; the nitrate (Є,H,N ̧,,HN→ ̧) may also be obtained in brilliant crystals, which have a very sour taste.

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be

When kreatine is boiled with mercuric oxide, the oxide is reduced, and a basic substance is formed, which Dessaignes calls methyluramine (Є,H,N ̧; 1610). The same substance may be obtained by boiling kreatine with sulphuric acid and peroxide of lead. When a solution of nitric oxide is transmitted through a solution of kreatine nitrate, an abundant disengagement of gas occurs; on neutralizing with caustic potash, separating the nitre by crystallization, and adding nitrate of silver, a crystalline compound is obtained (E,H,N,AgNO3), composed of nitrate of silver with a new base, to which Dessaignes assigns the formula €,H,N.

If kreatine be boiled with either sulphuric, hydrochloric, nitric, or phosphoric acid, it is decomposed, each atom losing an atom of water; whilst kreatinine is formed, and enters into combination with the acid :

Alkaline bodies produce with kreatine a different result. If, for instance, to a boiling solution of kreatine, crystallized baric hydrate, equal in weight to ten times that of the kreatine, be added, the kreatine is gradually decomposed, another new alkali termed sarkosine is formed, and urea is found in the liquid; one atom of hydrated kreatine furnishing the elements of one atom of sarkosine and one of urea :

By continued boiling with baryta, the urea itself is decomposed into ammonia, which is expelled during the ebullition, and carbonic anhydride, which combines with the baryta.

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(1608) Kreatinine (Є,H,N,O= 113).-This base may be procured from urine by the method already described (1607). It may also be obtained by boiling kreatine with hydrochloric acid; kreatinine hydrochlorate is thus formed, and from this the acid may be separated by boiling it with hydrated oxide of lead in excess ; a yellow, insoluble lead oxychloride is formed, and the kreatinine remains in solution. Its crystals require about twelve parts of cold water for solution, and they are still more soluble in hot water; kreatinine is also dissolved abundantly by boiling alcohol, and it crystallizes on cooling. Its aqueous solution restores the blue colour to reddened litmus, and it expels ammonia when heated with solutions of ammoniacal salts. It has a strong tendency to form basic double salts: for example, if a solution of nitrate of silver, moderately concentrated, be mixed with one of kreatinine, it becomes converted into a magma of white needles, which are very soluble in boiling water; and a similar compound is formed when a solution of corrosive sublimate is substituted for that of nitrate of silver. The chloride of zinc and kreatinine [(E,H,N ̧→),ZnCl2] is also sparingly soluble. With the salts of copper, kreatinine forms a blue crystallizable compound. Both the sulphate and the hydrochlorate of kreatinine may readily be obtained in crystals.

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(1609) Sarkosine, from oàpë, flesh (¤ ̧H,NO2=89).—In order to prepare this alkali, the solution of kreatine must be boiled with ten times its weight of baric hydrate until all odour of ammonia shall have disappeared. The excess of baryta is to be removed by a current of gaseous carbonic anhydride; the solution is to be boiled, filtered, and evaporated to the consistence of syrup, from which the sarkosine may be obtained in foliated crystals. In

790

SARKOSINE-METHYLURAMINE.

order to ensure its purity it may be converted into the form of sulphate, the aqueous solution of which may be decomposed by pure baric carbonate. Sarkosine crystallizes in right rhombic, perfectly transparent, colourless prisms, which are freely soluble in water, sparingly so in alcohol, and insoluble in ether. At a temperature a little above 212° they melt, and may be sublimed unchanged. Its aqueous solution has a sharp, sweetish, somewhat metallic taste, but has no action on vegetable colours. It forms crystallizable salts, which have an acid reaction. The sulphate (2 Є,H,Nе„H2SO,нH2O) crystallizes in colourless cubes. With platinic chloride sarkosine gives a double salt, which by spontaneous evaporation may be obtained in large yellow flattened octohedra [(Є,H,NO2)2, 2 HCl,PtCl, 2 H2O]. Sarkosine is isomeric with alanine and carbamic ether (urethane), as well as with lactamide, but quite distinct from all these bodies in properties, and is distinguished from them by its insolubility in ether and in alcohol. From its reactions Strecker considers it to be methyl-glycocine,* Є2H2(ЄH ̧)(H2N)→2 (1615). And Volhard (Liebig's Annal. cxxiii. 261) has experimentally confirmed this view by preparing sarkosine directly by heating an excess of methylia with chloracetic acid in a sealed tube to about 266° (130° C.).

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(1610) Methyluramine (Є,H,N ̧=73).—When an aqueous solution of kreatine or of kreatinine is boiled with mercuric oxide, carbonic anhydride is evolved, the oxide is reduced, and on evaporating the solution a copious crystallization of methyluramine oxalate takes place :

When the oxalate of the base is decomposed by milk of lime, methyluramine is liberated, and may be obtained in the form of a colourless deliquescent mass, by evaporating the solution in vacuo. It is powerfully alkaline, and absorbs carbonic acid rapidly from the air. It has a caustic, somewhat ammoniacal taste. When heated on platinum foil it is almost wholly volatilized. If boiled with baryta water it is decomposed, and vapours of methylia are

*It is worthy of remark, that both kreatine and sarkosine yield methylia when distilled with a mixture of sodic hydrate and lime, and sarkosine, when heated with sulphuric acid, is decomposed with effervescence, emitting vapours of a peculiar, stupefying odour, whilst methylia sulphate is formed in the liquid.

evolved. Methyluramine, in fact, contains the elements of methylia and of urea minus those of water :

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Ꮋ Ꮎ.

It

Methyluramine oxalate (2 €,H,N,,H,¤ ̧¤, 2H,→) crystallizes in flattened, double prisms, which are very soluble in water. is easy to prepare other salts of the base, such as the hydrochlorate, the nitrate, and the sulphate, by decomposing the oxalate with a solution containing an equivalent quantity of calcic hydrochlorate, nitrate, or sulphate.

(1611) Guanine (E,H,N ̧=151) was obtained by Unger from guano; it is also found to constitute the principal portion of the excrement of the garden spider (Epeira diadema), and it was found by Scherer in the pancreas of the horse. In order to obtain it from guano, this substance must be boiled with milk of lime until the liquid shall have acquired a yellowish-green tint instead of a brown colour. The liquid must then be filtered, and neutralized with hydrochloric acid. The guanine is slowly deposited, mixed with uric acid, and assumes the form of a flesh-coloured precipitate. This precipitate, when boiled with hydrochloric acid, gives up the guanine, and on cooling, a compound of this body with hydrochloric acid is obtained in crystals: the acid may be removed by digestion with ammonia. Certain specimens of guano were found to yield nearly 6 per cent. of this substance. Guanine forms a yellow powder which is insoluble in water, alcohol, and ether. It appears to possess the properties of a feeble base, and is soluble in hot dilute acids, forming unstable compounds with them. Guanine forms both normal and acid salts, the normal compound with hydrochloric acid being [(Є,H,N,,HCl),H ̧Ð ?], and the acid salt (ЄH.N ̧, 2 HCl); both of them lose the whole of their acid on being heated to 392° (200° C.). Other salts of guanine contain three atoms of the base and four of acid. Guanine forms a crystallizable double chloride with platinic chloride [(E,H,N,O,HCl),PtCl,, 2 H2O]. Guanine also combines with the alkalies, and is more soluble in alkaline solutions than in the acids. It is readily oxidized by a mixture of potassic chlorate and hydrochloric acid, yielding numerous products, among which are parabanic acid, oxaluric acid, and urea, the result of the decomposition of parabanic acid (1625), as well as a new base termed guanidine by Strecker:

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2

Guanidine.