98 



distillate was fractional ; the first portion gave no colour with starch 

 test ; it contained a minute trace of sulphurous acid. The second 

 portion was highly acid ; it was made slightly alkaline, evaporated 

 nearly to dryness, and then gave most positive evidence of nitrous 

 acid by Price's test, and also by decolorizing a deep solution of 

 indigo. 



Thus before the salt of ammonia was taken no nitrous acid could 

 be detected in the urine, whilst after the ammonia nitrous acid was 

 proved to be present, not only by Price's test, but by the indigo test 

 also. 



In conclusion, it results from these experiments, 1st, That in 

 Price's test sulphurous acid produces exactly the opposite effect to 

 nitrous acid, and even hinders nitrous acid from liberating iodine 

 from hydriodic acid. 



2ndly. That phosphoric acid, when mixed with urine containing 

 nitre and distilled very low, does liberate nitrous acid ; though when 

 used instead of sulphuric acid, it does not enable the nitrous acid to 

 be detected so readily as when the latter acid is employed. 



Hence the experiments performed in Professor Lehman n's labo- 

 ratory by Herr Jaffe*, do not invalidate Price's test for nitrous acid 

 in the way Professor Lehmann supposes ; and by again repeating 

 some of my former experiments, I still arrive at the conclusion that 

 when ammonia is taken into the body nitric acid may be detected 

 in the urine, but that the quantity which can be made to appear is 

 so small that the most delicate method is required for its detection. 

 This however is no prqof that a much larger quantity may not be 

 lost in the process for obtaining it from the urine. 



* Erdmann's Journal, vol. lix. p. 238, 1853. 



