94 THE CANADIAN NATURALIST. [March 



" prevent oxidation of organic, but not of inorganic substances ; 

 " tliey will not prevent iron from rusting." 



Pettenkofer states that ^' they arrest, but do not destroy 

 fermentation." This seems, however, to depend greatly on the 

 strength of the acids used, and the conclusion drawn by the 

 author is that all vital action may be destroyed by strong acids, and 

 that in various degrees of dilution they are more or less potent on 

 the lower organisms — both animal and vegetable. Experiments 

 made by Mr. Crookes showed that a solution containing 1 per 

 cent of carbolic acid: — 1** preserved meat with fresh odour; 

 2° preserved gut skin, size, and glue; 3° stopped the fermentation 

 of yeast in a saccharine solution ; 4° killed cheese-mites, infusoria 

 fish, caterpillars, beetles, and gnats. 



Cresylic acid, which accompanies carbolic acid, is also a power- 

 ful antiseptic, and has much less coagulating power over albumen, 

 than carbolic acid. It has a stronger smell, bears greater dilu- 

 tion, and is probably a more powerful disinfectant than carbolic 

 acid, and better adapted for injection into the veins of diseased 

 animals — a process which was found of great service during the 

 Cattle Plague. 



" Petroleum is a very poor disinfectant compared to tar acids. 

 " Probably it contains a little either of carbolic acid or of some 

 " allied compound, to which it owes all its disinfecting power. 

 '' Tar oils which most resemble petroleum have also a weak disin- 

 " fecting power ; but, when the acids are washed out by water, 

 " there is no disinfecting power remaining." 



Lime is a good disinfectant, but very weak. As it is, however, 

 cheap and abundant, it is an excellent auxilliary, especially 

 applied as lime-wash to the walls of buildings. It is, certainly, 

 greatly raised in value by admixture with carbolic acid, which is 

 thus retained in contact with large surfaces of air which it com- 

 pletely disinfects. The process, however, needs frequent repeti- 

 tion, if the generation of air poisons be continuous, as in stables, 

 cattle sheds, or slaughter-houses. 



After consideration of the several metallic salts, which have 

 been recommended as disinfectants, (of which our author forms a 

 less favourable opinion than of the tar acids,) attention is called 

 to the necessary removal of manure and refuse by water-closets 

 and sewers, earth closets and middens. Of the first he says : — 

 "The water-closet system is a great luxury, unquestionably, but 

 " like all other luxuries, it is taxed. ^ * ^ It is the very 



