1871J The Theory of Atmospheric Germs, 169 



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 at- 

 tempted to ascertain the results which occur when the 

 air alone is influenced by certain agents, the materials being 

 left intact. In this way the evidence of the results obtained 

 from experiments with heat may be tested by the evidence 

 of other agents of vital destruction.* 



The results obtained may be thus briefly summarised :— 



1. Putrefaction, mildew-formation, and the appearance of 

 organisms can be checked or absolutely prevented by the 

 existence of certain agents in the air supplied to a putrescible 

 body. 



2. 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) camphor; 

 (5) iodine, phosphorus, creosote, carbolic acid. 



3. The agents which stop fermentation are vegetable, not 

 animal, poisons. Fungi will grow in the presence of hydro- 

 cyanic acid and of strychnia. 



4. Comparative experiments show that a given volatile 

 agent is far more efficient when it is contained in the air 

 supplied to a putrescible solution than when an equal 

 quantity is mixed with the solution itself. 



(5) All fungoid organisms can be prevented by the presence 

 of a minute proportion of creosote, carbolic acid, ammonia, 

 hydrochloric acid, or sulphurous acid in the air, though 

 beneath the surface of the fluid are found numerous 

 bacteria and vibrios. 



There seems to be no escape from the conclusion that 

 the germs of fungi exist in the air and are destroyed by the 

 volatile poisonous agent. 



* See paper by the Author in the " Chemical News" (vol. xxii, pp. 241, 254), 

 " Evidence concerning the Germ Theory of Fermentation afforded by the 

 Action of certain substances when Suspended in the Air." 



VOL. VIII. (o.S.)— VOL. I. (N.S.) 



