52 ON PUTREFACTION. 



calculatedto Now it is clear that the smallest diminution of air in the 



shewminute bottle would be marked by a corresponding fall of the mercury 

 variations. .,.,.. . . , »• 



in the tube, the calibre ot which was not more than one line. 



Or, on the contrary, any evolution of gas would raise the 



mercury in the tube. 



No absorption The apparatus remained three days without any change of 



took place. mercury in the tube. On the fourth day the mercury began to 



rise, and continued to rise until the experiment was suspended, 



which proves that there was no absorption of oxygen gas by the 



putrefying substance. The thermometer included in the bottle 



stood at 60, during the experiment. This apparatus is easily 



constructed and may be used for many similar purposes as a 



gasometer. 



Putrefaction As from all these experiments it appeared that no oxygen 



effected g as was absorbed by the putrefying substance, I determined to 



of air : exclude the atmospheric air altogether. This I attempted first 



by the following experiment, 

 in carbonic I put some fresh meat into a glass vessel — filled it with mer- 



cury — placed it in the pneumatic cistern, and filled it with car- 

 bonic acid. In this situation it was kept three days 3 at the 

 end of which period the flesh was found to have undergone the 

 putrefactive fermentation 3 yet all air except carbonic acid was 

 excluded. Though Sir John Priogle and Dr. Mc Bride (and 

 the latter from actual experiments) contended for the antiseptic 

 powers of fixed air. The thermometer during this experiment 

 stood at 70. 

 and In But as my object was to exclude oxygen gas, and as car- 



fcydrogen ga 3 . jjonic acid contains that as one of its components, I thought it 

 nor impossible but that the animal matter might abstract a 

 portion of the oxygen from the carbonic acid, and convert it 

 into carbonic oxyde : as is the case with iron, zinc, tin, and 

 certain other metals. I therefore repeated the experiment in 

 every circumstance as before, except that I substituted hydrogen 

 for carbonic acid gas : but with precisely the same result, 

 putrefaction went on as well as in any of my former experi- 

 ments, 

 and in other * tried sulphuretted hydrogen and n itrogen gases in the same 

 ga«e*. manner, and with the same result. 



I then fell upon a second method of excluding atmospheric 

 air and oxygen gas. 



I to 





