50 DR. R. ANGUS SMITH ON 



portion of the organic matter was retained, two separate 

 substances of an organic kind existed in the vapour ; but 

 even this might not be fair, as water absorbs from the gas 

 readily, and begins instantaneously to give out again. I 

 draw, however, this conclusion, that there is a distinct 

 amount of carbon other than that of the carbonic acid, 

 and that a part of the bodies containing carbon is absorbed 

 by acids, others by alkalies. Other experiments show that 

 more is absorbed by alkalies. There was present, in fact, 

 the substance of which I am in search, but of which I 

 can give no account. 



I was inclined to believe that when such a large amount 

 of air was passed through the salt, not only was the sul- 

 phide of lead oxidized, as was plainly seen, but the organic 

 matter was oxidized also, and perhaps a facility given to its 

 oxidation by the presence of the salt. I believe this ex- 

 plains also why such a small amount of organic matter is 

 obtained when impure air is passed through water. In the 

 atmosphere itself the organic matter begins to be oxidized 

 as rapidly as it is freed, and so prevents accumulation ; and 

 in passing air through water facihties for continued oxida- 

 tion still exist undiminished, and perhaps increased. The 

 method of freezing, so as to obtain the moisture and the 

 dissolved matter at the same time, is very effectual, but it 

 is a very troublesome operation, and, when it lasts long, 

 it becomes expensive also. Besides, the actual vapours of 

 putrefaction are not in this way obtained, on account of 

 the rapid oxidation which occurs when they are mixed 

 with the atmosphere. 



It was in order to avoid the imperfect results alluded to 

 that I adopted the simple method of enclosing the blood 

 in a vessel, and collecting the gas which escaped under 

 pressure. It might be said that this really does not express 

 the exact condition of substances putrefying in nature ; and 

 I was deterred from it at first. But on consideration and 

 on experiment it was seen that the blood required the as- 



