578 Transactions of the American Institute. 



that these processes were essentially chemical, it was naturally proba- 

 ble that the agents which suppressed them should be susceptible of a 

 chemical classification. If the processes were, as asserted, those of 

 oxidation, it would surely be not unreasonable to expect that the 

 agents which arrest them should also arrest oxidation ; but common 

 experience taught an absolutely contrary lesson — that oxidizing agents 

 were the most efficient in arresting the processes. Again, on the 

 chemical theory, there ought to be some quantitative relation between 

 the amount of a chemical agent employed and the degree of its influ- 

 ence ; but the fact is that an agent present in such feeble quantity as 

 to be capable of no appreciable chemical effect on the mass of putres- 

 cible material, is yet capable of stopping all putrefaction. Further- 

 more, agents, such as carbolic acid, whieh are proved to exert no influ- 

 ence whatever on processes purely chemical, are among the most effi- 

 cient of all means for preventing putrefaction and fermentation. A 

 large series of observations show, on the other hand, that the agents 

 arresting these processes exert their influence precisely in so far as 

 they are iwisonous agents to low organisms. If at any stage of the 

 process these microscopic organisms are rendered lifeless, the process, 

 with all its attendant phenomena, ceases ; on the other hand, the 

 overt signs grow with their growth, strengthen with their strength, 

 subside when they languish, and cease when they die. Hitherto 

 experiments have usually been made with the view of ascertaining 

 the effects of antiseptic agents when mixed with putrescible material ; 

 but the author has attempted to ascertain the results which occur 

 when air alone is influenced by certain agents, the materials being 

 left intact. In this way the heat may be tested by the evidence of 

 other agents of vital destruction. The results obtained may be thus 

 briefly summarized : 



I. Putrefaction, mildew formation, and the appearance of organ- 

 isms can be checked or absolutely prevented by the existence of cer- 

 tain agents in the air supplied to a putrescible body. 



II. The power of such agents can in no sense be measured by their 

 chemical constitution or characters. From many experiments the 

 following expresses their order of efficiency, from weakest to strongest : 

 {1.) Chloride of lime. (2.) Sulphurous acid, ammonia, sulphuric ether. 

 (3.) Chloroform. (4.) Champhor. (5.) Iodine, phosphorus, creosote, 

 carbolic acid. 



III. Tne agents which stop fermentation are vegetable, not animal 

 poisons. Fungi will grow in the presence of hydrocyanic (prussic) 

 acid and of strychnia. 



