356 AGRICULTURAL BACTERIOLOGY 



is probably as effective a disinfecting agent as can be used 

 to advantage in ordinary stable disinfection. It can be 

 made more effective by the addition of carbolic acid or 

 chloride of lime. 



In all disinfecting processes it is essential to use plenty 

 of the agent. The cheapness of lime is thus an advantage, 

 as is the ease with which it can be procured. It is also to 

 be recommended when carcasses of animals that have died 

 from transmissible diseases must be buried instead of being 

 burned. In such cases the carcass should be well covered 

 with lime, and then the dirt returned to the excavation. 



Carbolic acid. Carbolic acid is prepared from coal-tar 

 and is sold in the form of white crystals which melt below 

 the boiling-point of water, and which remain liquid on the 

 addition of 5 per cent, of water to the melted acid. It is 

 used as a disinfectant in solutions containing from 1 to 5 

 per cent, of the pure acid. Its action is not greatly re- 

 tarded by the presence of organic matter, as is the case 

 with so many other disinfectants; hence it can be used for 

 the disinfection of feces from typhoid patients, and the 

 treatment of sputum of tubercular people. 



Carbolic acid, or phenol as it is often called, does not 

 find wide use on the farm, because of its expense, its cor- 

 rosive action on the skin, and its poisonous properties. 



Coal-tar disinfectants. After the carbolic acid has been 

 removed from coal-tar, the residue still contains substances 

 that have a disinfecting action. From this residue there is 

 now prepared a great number of disinfectants commonly 

 known as coal-tar- or cresol disinfectants, a term that ap- 

 pears in the name of many of the proprietary compounds, 

 such as kresol, kreso, kresolig. The value of these com 

 pounds varies widely. Some are about equal to carbolic 

 acid, while others are ten times as effective. The great 

 majority are from two to three times as effective as phenol 



