ITS QUANTITATIVE ANALYSIS. 445 



stances dissolved by the water; the insoluble parts may now be 

 easily incinerated, and their quantity thus determined. The further 

 analysis must then be completed by the ordinary methods. 



The combustion of the carbon by oxygen in a platinum 

 capsule seems to me, at all events in the case of the urine, to be 

 altogether unsuitable, on account of the volatilization of the 

 chlorine, and even of sulphuric arid phosphoric acids. 



Chambert's* method is the best adapted for a continuous 

 series of determinations of the mineral substances of the urine. 

 The evaporation of the urine must be effected in the following 

 manner : a tube two centimetres in width is provided, at its lower 

 extremity, with a glass tube, twice bent at right angles, and ter- 

 minating in a sphere ; this sphere again opens into a minute drawn- 

 out glass tube, whilst the upper part of the wide tube passes into 

 a small glass tube into which a cock is inserted. This apparatus 

 is filled with urine, and so secured to the stage of a Berzelius's spirit 

 lamp that the opening of the glass sphere is brought immediately 

 over a heated platinum crucible. By means of the cock we may 

 regulate the access of the air, and the corresponding dripping of 

 the urine into the crucible. Chambert allows the urine to escape 

 so slowly, that one drop is suffered to evaporate before another 

 succeeds it. In this manner 100 or 110 grammes of urine may be 

 evaporated in the course of an hour and a half. Loss by spirting 

 may be tolerably well prevented by carefully and uniformly regu- 

 lating the escape of the fluid. The layer of carbon which speedily 

 invests the crucible does not amount to the twentieth part of that 

 obtained by the ordinary method. 



In order to effect the combustion of the residuary carbon, 

 distilled water should be suffered to drop on the glowing carbon 

 from the same reservoir in which the urine was previously con- 

 tained ; the combustion of the carbon will go on with tolerable 

 rapidity at those points with which the water comes in contact, 

 owing to the well-known decomposition of this fluid at a red heat ; 

 but as some carbon will always adhere to the walls, it must 

 repeatedly be removed, and more water allowed to drop upon it. 

 The experiment does not gain in accuracy by this method, but the 

 combustion is effected with greater rapidity. Hence we may 

 perceive that, although this analysis is very applicable in certain 

 cases, it cannot, for many reasons, lay claim to any great degree 

 of exactness. 



It is obvious from, the above remarks, that the composition of 

 * Ilecueil des M&noires de mdd. et de pharm. militaire. T. 58, p. 328. 



