62 



DB. K. ANGUS SMITH ON ANCIENT AND 



felt. The senses in many cases come second in sensitiveness. 

 Although chemical analysis often comes behind, it is capable, 

 no doubt, of changing its place and going foremost. 



6. Old writers, speaking of animal functions and of diseases, 

 use the word "fermentation." Fermentation is the splitting 

 up of a body into several parts, by a power within itself, or 

 imparted to it by another body in contact with it. Sugar 

 may give out alcohol and carbonic acid ; but sugar also may 

 give mucic acid and lactic acid. Some of it may form another 

 body, fusel,oil. 



There are, then, some bodies which act on each other 

 gratuitously, as it were, that is, they do not require either a 

 proportionate amount of physical force or an atomic equivalent 

 so as to act by quantity. Their power is apparently in pro- 

 portion to their quality, not their quantity. Sulphuric acid 

 decomposes common salt ; when it has satisfied its equivalent, 

 it is placid, and the common salt beside it is quite untouched. 

 Not so with a ferment; it ends with the material to be decora- 

 posed, — that is, if sulphuric acid acted like common salt, it 

 would set in motion the decomposition, so that it would never 

 end till the salt were done. This is not exactly the case with 

 the action of a ferment on sugar, because that requires a 

 certain quantity ; but of the action of a ferment on grain, 

 for example, where the ferment may be reproduced as it 

 is used. 



7. Bodies dried do not decompose ; moisten them, and they 

 begin to putrefy. 



8. The infectious matter of fever, plague, and cholera is 

 not a true gas, it does not diflFuse. It runs unequally, and 

 without following the laws of diffusion, along streets and to 

 distant towns. A true gas would go everywhere equally, 

 unless it were taken more to one place than another by 

 differences of wind and moisture. 



9. The similarity of decomposition produced in one person 

 by contact with another, is so analogous to fermentation or 



