452 THIRD CLASS OF MINERAL CONSTITUENTS. 



In the sweat, especially in that from the axillae, the occurrence 

 of ammonia is incontestable. In the urine it is assumed to exist in 

 larger quantities than is actually the case. In the solid excrements 

 which may be regarded as already in a state of decomposition, and 

 which very soon develope ammonia when exposed to the atmo- 

 sphere, Berzelius* believes that there is no carbonate of ammonia. 

 Important as is the occurrence of ammonia in the vegetable juices 

 for the renovation of the nitrogenous compounds, the animal 

 organism appears to stand in little need of this substance. Indeed 

 the process of decomposition by which the individual constituents 

 of the organs are reduced to effete nitrogenous matter, by no means 

 gives rise to the formation of ammonia, for in that case we should 

 certainly find a far larger quantity of the salts of this alkali in the 

 excretions. Urea is the principal nitrogenous product of decom- 

 position which is formed within the body from the nitrogenous 

 substances. 



The blood, chyle, lymph, and milk, the fluids of the egg, and 

 the secretions of the serous membranes either contain no ammonia 

 or only extremely small quantities of it. In the pulmonary exha- 

 lation, on the other hand, small quantities of ammonia may always 

 be recognised with great certainty. 



Almost all histogenetic substances develope ammonia when 

 treated with dilute acids or alkalies. 



Observers have often believed that they had detected hydro- 

 chlorate of ammonia by the microscope after evaporating the alco- 

 holic extract of animal fluids, when in reality, they saw the efflo- 

 rescing forms of chloride of sodium, which, in the presence of cer- 

 tain organic matters (as, for instance, in the chyle) and especially 

 when rapidly evaporated, separates in arborescent groups very similar 

 to those of hydrochlorate of ammonia. 



Lecanu and Denis failed in detecting any salts of ammonia in 

 the blood ; Marchand and Colberg were equally unsuccessful in 

 reference to the lymph, and Schwartz, and Simon, in reference to 

 the milk. 



Even in the urine the quantity of ammonia is extremely small r 

 as is shown by the following experiments. I allowed the greater 

 quantity of water in the morning urine to freeze, and thus obtained 

 a very concentrated, almost wine -red urine, in which we might 

 assume that there was no decomposition of the constituents ; when 

 carefully treated with caustic potash, it yielded a precipitate which 

 even after remaining for a long time in contact with the urine, con- 

 * Lehrb. der Chem. Bd. 9, S. 180. 



