kreatinine causes instantly a precipitate formed of crystalline grains, appearing under the microscope as round masses, formed of very small needles concentrically grouped.

ammonia,

Kreatinine expels ammonia from ammoniacal on salts of salts, and forms with salts of oxide of copper crystal- and on salts lisable double salts of a fine blue colour.

of copper,

ide of plati

num.

Bichloride of platinum, when hydrochlorate of on bichlorkreatinine is added to it, causes no precipitate if. the solution is diluted; but on evaporation in a gentle heat, there are formed deep yellow transparent crystals of considerable size, very soluble in water, less so in alcohol.

A solution of kreatinine to which bichloride of platinum and hydrochloric acid have been added, yields, when evaporated, the same compound, which is a double salt analogous to the double chloride of platinum and ammonium.

The composition of kreatinine is easily deduced from the action of hydrochloric acid gas on kreatine. 0.5775 gm. of kreatine in crystals increased in weight when exposed to a current of that gas, at 202° by only 0.002 gm. The residue, dissolved in water, and precipitated by nitrate of silver, gave 0.5605 gm. chloride of silver, corresponding to 24.68 per cent. of hydrochloric acid.

The fact that the weight is not altered in this experiment, implies that for 24-68 parts of hydrochloric acid absorbed, an equal or very nearly equal weight of water has been expelled.

The compokreatinine

sition of

deduced

from its for

mation.

Kreatine, in forming kreatinine,

Now since crystallised kreatine, when heated alone to 2120°, loses 12.08 per cent. of water, it is evident that twice this quantity has been expelled, because otherwise, when 24.68 per cent. of hydrochloric acid had been absorbed, the weight must have increased. Since, moreover, 1 eq. of hydrochloric acid weighs 36·5 (H=1) and that weight corresponds to 4 eq. of water, it follows that for 1 eq. of hydrochloric acid absorbed, 4 eqs. of water have been expelled.

It follows further, that anhydrous kreatine must gain in weight when exposed to hydrochloric acid gas, to the amount of 14.05 per cent. In fact, 0.5820 gm. of anhydrous kreatine, under these circumstances, absorb 0.084 gm. of hydrochloric acid, corresponding to 14.46 per cent., a coincidence as close as could be obtained.

The conversion of kreatine into kreatinine, by the action of mineral acids, depends, therefore, on the loses 4 eqs. separation of 4 eqs. of water. If we subtract these from the formula of crystallised kreatine, the composition of kreatinine in 100 parts is as follows:

of water.

Formula.

Analysis of kreatinine.

In accordance with this theoretical result there

were obtained by combustion with chromate of lead the following numbers:

0.3418 gm. of kreatinine yielded 0.5332 gm. carbonic acid, and 0.1965 gm. water.

The same substance yielded, when burned, a gaseous mixture, in which, for 434 volumes of nitrogen gas, there were found 1,132 vol. of carbonic acid.*

According to this analysis, kreatinine contains

and caffeine.

If we compare with the formula of kreatinine that Kreatinine of caffeine (théine), it appears, that kreatinine contains the elements of 1 atom of caffeine + 1 atom amide. Caffeine is

The compound dis

urine by Pettenko

fer

*

Kreatine and Kreatinine, constituents of human urine. If we compare the results of the analysis of kreacovered in tine and kreatinine with the composition of the substance discovered three years since by Pettenkofer in human urine, and analysed by him, we perceive at once, that both kreatine and kreatinine must stand in a definite relation to that body. Pettenkofer found that this substance, when burned, yielded a gaseous mixture, containing, for 8 vol. of carbonic acid, 3 vol. of nitrogen. This is the same contains the proportion, as is contained in kreatine and kreati

same pro

portions of nine; although, on the other hand, he found a

carbon and

nitrogen as variation in the proportion of hydrogen and oxygen.

kreatine and

kreatinine. The substance from urine contains 1 eq. of water less than anhydrous kreatine and 1 eq. more than kreatinine.

Pettenkofer's pro

cess.

Although I had no reason to doubt the accuracy of Pettenkofer's analysis, yet I considered it desirable to compare the properties of the substance from urine with those of kreatine and kreatinine.

According to Pettenkofer's process for its preparation, fresh human urine is neutralised with carbonate of soda, evaporated till the salts crystallise out, then extracted by alcohol, and mixed with a concentrated solution of chloride of zinc. In this mixture, there are deposited, after some hours or days, small granular hard crystals, frequently in crusts, which contain chloride of zinc and a crystal* Annalen der Chemie und Pharmacie, vol. lii. P. 97.

lisable organic substance. When these crystals are dissolved in hot water, the zinc separated by means of baryta, the filtered liquid evaporated, the residue acted on by alcohol, the alcoholic solution deprived of baryta by sulphuric acid, and the liquid, which now contains hydrochloric acid, sulphuric acid, and the organic compound, boiled with oxide of lead, the sulphuric and hydrochloric acids are thus separated, and the organic compound remains dissolved in alcohol, and gives on evaporation a crystalline white mass, which instantly reproduces the original crystalline precipitate when its solution is mixed with chloride of zinc.

process

the author.

According to my experiments, this substance may Simpler be obtained from urine by a simpler process. The proposed by urine is neutralised by milk of lime, and then solution of chloride of calcium is added as long as it causes a precipitate of phosphate of lime. The liquid is then filtered and evaporated till the salts crystallise out on cooling. The mother liquor is separated, without the use of alcohol, from the salts, and mixed with a syrupy solution of neutral chloride of zinc, in the proportion of about ounce to 1 lb. of the

extract.

After three or four days the greater part of the zinc-compound of Pettenkofer is found to have crystallised in rounded yellow grains. The deposit is well washed with cold water, then dissolved in boiling water, and hydrated oxide of lead added to the solution, till it acquires a strong alkaline