488 



its dew point, the moisture which then separates appears to 

 contain a volatile putrid substance in solution. By passing 

 the air from any putrid source through a tube cooled by ice- 

 cold water, I have been able to collect a considerable quantity 

 of this solution ; but as yet I have been unable to separate 

 the active principle from the water and other compounds 

 with which it appears to be associated, and consequently 

 have not been able accurately to ascertain its composition or 

 properties. I think, however, that I have made out satisfac- 

 torily that it is a compound of nitrogen, but certainly not 

 ammonia or nitric acid ; for on first ascertaining the amount 

 of ammonia contained in a given quantity, and the absence 

 of nitric acid or cyanogen, I found the quantity of ammonia 

 very much increased by subjecting it to an organic analysis. 

 At first I suspected it to be one of those volatile bases 

 recently discovered in Dipel oil, but subsequent observation 

 led me to conclude that such was not the case. That it is 

 a substance capable of undergoing rapid decomposition is 

 evident from its watery solution, at first perfectly transparent, 

 but in a few hours after being collected becoming perfectly 

 milky. In one instance a gas was evolved during its change, 

 but I was not certain whether it might not have been con- 

 densed by the cold. I therefore consider it a nitrogenous 

 organic compound in a state of rapid transformation — a 

 substance, therefore, similar to yeast in many of its pro- 

 perties, and which, like yeast, is capable of communicating 

 a similar state of transformation to many nitrogenous bodies 

 with which it comes in contact. That this communication of 

 motion or change to matter in a state of rest really takes 

 place in numerous instances, is a fact so well understood by 

 chemists, that I must apologise for introducing a few brief 

 illustrations. 



One of the most remarkable changes of this kind arises 

 when amygdalin, one of the constituents of the bitter 



