528 APPENDIX. 



will of course likewise precipitate upon the addition of bichlo- 

 ride of platinum, it is necessary to determine the exact pro- 

 portion in which these salts are present in the urine under 

 examination. For this purpose a separate weighed portion of 

 urine is precipitated with bichloride of platinum, and the 

 amount of precipitate substracted from the former. 



Two samples of urine of 7 grammes each, treated accord- 

 ing to this method, yielded 0-202 grammes of urea, or 2'88g, 

 and 0-199 grammes of urea or 2'84g. Fourteen grammes of 

 the same urine was treated according to the ordinary plan ; they 

 yielded 0-617 grammes of nitrate of urea, or 2'15g of urea. 

 The extractive matters of the urine yielded no ammonia. 



These experiments prove that the method of determining 

 urea in the form of ammonio-bichloride of platinum yields 

 much more accurate results than the plan usually adopted ; it 

 may, therefore, in many cases be advantageously employed, 

 with this precaution, that all substances likely to interfere with 

 the accuracy of the process (as uric and hippuric acids, albu- 

 men, &c.) be previously removed. It might be advisable in 

 certain cases to separate the urea in the first place by means 

 of oxalic acid, and then to decompose the oxalate with sul- 

 phuric acid. 



The following table may save trouble in calculation. 



1 atom of ammonio-chloride of platinum corresponds to 0-134498 of urea. 



2 0-268996 



3 0-403494 



4 0-537992 



5 0-672490 



6 0-806988 



7 0-941484 



8 1-075984 



9 1-210482 



The author concludes his paper by an acknowledgment of 

 the kind assistance of Liebig. 



In principle the method adopted by Heintz 1 is so similar to 

 the above, that it is unnecessary to enter into the details. 

 Both writers agree respecting the inaccuracy of the ordinary 

 method. 



PAGE 238. Urine in Bright's disease. In Heller's memoir 

 already referred to, we find the following analyses of the urine 

 in this disease. 



1 Poggendorff' s Aunalen, No. 7, 1845. 



