487 



every change of atmospheric temperature, pressure, and 

 humidity. 



Although putrefaction is commonly regarded as a simple 

 process, generating substances the history of which is well 

 known, — producing sulphuretted hydrogen, phosphuretted 

 hydrogen, carbonic oxide, &c., yet I am convinced, from ex- 

 periments recently made, that the number of new compounds 

 formed during this process is much greater than is usually 

 imagined. It is, indeed, impossible to conceive the removal 

 of one atom of carbon, hydrogen, oxygen, or nitrogen from 

 any organic product, without, at the same time, leaving a 

 compound possessing a character entirely different from the 

 original. As these elements are gradually removed atom by 

 atom, or as they divide and subdivide, probably many times, 

 before the last products are given off, I maintain that some of 

 these intermediate compounds may be of a nature capable of 

 producing, when conveyed into the system, disease or death. 

 What is it that gives to the atmosphere in the neighbourhood 

 of putrefying organic remains the various odours which 

 characterise their presence ? In many instances neither 

 sulphuretted hydrogen nor phosphuretted hydrogen can be 

 detected. It is not the simple odour of ammonia, nor of 

 sulphuret of carbon ; these compounds in many cases are 

 absent. It is evidently some form of matter which has not 

 yet been isolated, and the exact nature of which is certainly 

 not understood. It is evident from this peculiar odour, which 

 it generally, though not always, gives to the atmosphere, and 

 more particularly from the deadly character which it inva- 

 riably communicates to that fluid when present in quantity, 

 that it is something capable of assuming the gaseous state, or 

 of being dissolved in air, like other volatile fluids. Although 

 it is impossible to detect any foreign substance in such air by 

 the usual process of eudiometric analysis, yet when the air 

 from the neighbourhood of stagnant drains is cooled below 



