in Liebig's drying apparatus, at a temperature of 240° F. (100° C.), to a current of dry hydrochloric acid gas, the weight of the apparatus increases at first; on continuing, however, the high temperature and current of hydrochloric acid gas for some time, very nearly the original weight of the apparatus is at last obtained. During the experiment water is constantly seen to leave the apparatus, until the weight of the apparatus remains stationary. If dried creatine be taken for the experiment, the apparatus shows an increase in weight. The body produced under these circumstances is neutral chloride of creatinine.

In the same manner, chloride of creatinine is obtained by dissolving creatine in concentrated hydrochloric acid, in a china dish, evaporating the solution, and heating the residue in the water-bath until all free hydrochloric acid has disappeared.

This salt contains one equivalent of hydrochloric acid and one equivalent of creatinine. It is easily soluble in boiling alcohol, and crystallizes from this solution in short, transparent, colourless prisms, which are easily soluble in water. On evaporation, it is obtained in large transparent laminæ of an acid reaction.

Chloride of creatinine + chloride of platinum.-A solution of chloride of creatinine, when mixed with chloride of platinum, and gently evaporated, yields rosy crystals, prisms of the double-salt. On rapid formation, this salt is obtained in yellowish-red, transparent granules. It contains 30.95 per cent. of platinum.

Sulphate of creatinine.-On adding to one part of creatine an equal weight of dilute sulphuric acid (composed of 27 parts of concentrated sulphuric acid and 73 parts of water), evaporating to dryness, and heating until all moisture is volatilized, neutral sulphate of creatinine is obtained. It may also be produced by adding to a boiling saturated solution of creatinine dilute sulphuric acid, until a strongly acid reaction is perceived, and evaporating to dryness. A white crystalline mass is thus obtained, easily soluble in hot alcohol. On cooling, the solution becomes milky, and, on becoming clear, deposits transparent, concentric, quadratic plates of neutral sulphate of creatinine. They remain transparent and clear at a temperature of 240° F. (100° C.)

Chloride of zinc + creatinine.-On adding a syrupy solution of neutral chloride of zinc to a concentrated solution of creatinine, a white granular precipitate is immediately pro

duced, the microscopical appearances of which I have already described. This may be filtered from the mother-liquid after twenty-four hours, washed with cold water, in which it is very little soluble. It is much more soluble in boiling water, and crystallizes from a saturated solution, on slow evaporation in large granules, warts, and groups of needles. This salt, mixed with creatine, constitutes the substance originally obtained by Pettenkofer, and produced from urine by the first method.

From this salt and from the chloride creatinine may be separated by boiling with hydrated oxyde of lead, in the manner described for the first method. From the sulphate, creatinine may be obtained by adding to its boiling watery solution carbonate of baryta, until effervescence is not any longer produced, and the fluid has got an alkaline reaction. Sulphate of baryta being thus formed, pure creatinine remains in solution.

Observations on the quantity of Creatinine and Creatine discharged in given times by healthy individuals.

Observation 1.-Five days' urine from A, 28 years of age, weight of body 70 kilogrammes, was treated for creatinine and creatine by Liebig's process. The zine salt was decomposed by hydrated oxyde of lead. The mixture of the two substances obtained was separated by alcohol, the alcoholic solution of creatinine was evaporated to dryness in a waterbath. The drying process was completed with a chloride-ofcalcium-tube and an air-pump. There was obtained, creatinine, 3.1292 grammes.

The creatine which constituted the residue from the alcoholic extraction was washed into a silver capsule with boiling water, and evaporated to dryness. Its weight was creatine, 2.0175 grammes.

This gives 0-6258 grammes of creatinine per day, and 0.4095 grammes of creatine per day.

Observation 2.-Four days' urine from A, treated as usual, the zinc salt decomposed with lead, no charcoal used.

There were obtained, creatinine, 1.4532 grammes, equal to 0:3633 grammes for twenty-four hours.

The alcoholic extraction left creatine, 12120 grammes, equal to 0-3030 grammes for twenty-four hours.

Observation 3.-Two days' urine from B, aged 28, weight of body 72 kilogrammes. There were obtained two portions

of chloride of zinc creatinine, the second portion not quite pure. It was, therefore, recrystallized, and, together with the first, dissolved in boiling water. The zinc was then precipitated by sulphuretted hydrogen, after a little ammonia had been added to the solution. The mixture stood for several days to allow of perfect precipitation of the sulphuret of zinc. But when the filtrate was evaporated, redissolved, and, after a new filtration, re-evaporated, there was always again sufficient sulphuret of zinc formed to constitute an impurity. During these proceedings it was found that the ammonia which had been added, and which must have formed chloride of ammonium with the hydrochloric acid from the zinc salt, was gradually driven out by the creatinine, and the last portions of it disappeared with the alcohol which evaporated from the creatinine. The hydrochloric acid was removed with oxyde of lead and charcoal, the filtrate evaporated, the mixture of the residue obtained was separated by alcohol, and the quantities of substances obtained were as follows:

The creatine contained yet a very slight amount of creatinine; the figures for creatinine are, therefore, somewhat below the actual amount, those of creatine a little higher.

Observation 4.-Five days' urine from B, yielded 4:363 grammes of chloride of zinc creatinine (and creatine, as an admixture). After having been dissolved in boiling water, and made alkaline with ammonia, a current of sulphuretted hydrogen was passed through the solution for several days; the yellowish-white sulphuret of zinc was thereby precipitated. The filtrate was boiled for a length of time to drive the ammonia out of its combination, it was then evaporated, and the dried residue was treated with alcohol.

There were obtained, chloride of creatinine, 2:4072 grammes, which is equal to 2.93 grammes chloride of zinc creatinine, which, deducted from the above 4.363 grammes of zinc salt, leaves 1.433 grammes for the creatine contained in the zinc salt as an admixture.

The creatine obtained weighed 1·1201 grammes.

This loss, when distributed over the different operations, and in part accounted for by the abstraction of colouring matter by the lead and the charcoal used for the purpose, cannot be called excessive, though it is still considerable. The experiment illustrates the proportions between the creatine on the one hand, and the creatinine zinc salt on the other, contained in the crystallized substance obtained from the urine.

Secreted in five days, creatinine 1.8322 grammes.
creatine 1.1201 do.

do.

Do.
Secreted in one day,
Do.
do.

Observation 5.-Five days' urine from B, yielded 6-7663 grammes of crystallized substance (chloride of zinc creatine and creatine mixed), washed and dried. From this the amount of creatinine and creatine was ascertained by calculation, upon the basis of the parts found in the fourth

observation.

If 4-3630 grammes of crystallized zinc salt yielded 1-8322 grammes of creatinine, how much would be obtained from 6.7663 grammes of zinc salt?

4.3630 1.8322 = 6.7663 x

1.8322 × 6.7663
4.3630

2.8373 grammes

of creatinine secreted during five days.

4-3630 11201 (creatine) = 6·7663: x

1.1201 × 6.7763
4.3630

of creatine secreted during five days.

= 1.7370 grammes

Secreted in one day, creatinine 0.5674 grammes.
creatine 0.3474 do.

Do.

do.

Observation 6.-Five days' urine from A, yielded a quantity of crystallized zinc salt, which was washed, redissolved in boiling water, filtered, evaporated, and dried. When dry, it was a powder-like mass of a light-yellow colour, a sample of which, when burned on platinum foil, left pure oxyde of zinc on the foil. When exposed to the air, it attracted very little moisture. Its weight, when perfectly dry, was 4-6324

grammes. The amount of creatinine and creatine was calculated upon the basis of observation 4.

of creatine contained as an admixture in the zinc salt.

There was a second portion of crystallized substance obtained from the mother-liquor. It was, however, impossible to free it from impurities, and it could, therefore, not be approached by quantitative analysis. The above values are, therefore, only expressive of a minimum, since there was certainly more creatine and creatinine present in the urine than could be obtained pure.

The above observations of the quantity of creatinine and creatine discharged by healthy individuals in a given time, have been arranged in the following tables :