INFECTIOUS DISEASES OV CATTLE. 361 



disease is likely to run a chronic course, as in tuberculosis. The next 

 important step is to separate the well from the sick by placing the 

 former on fresh ground. This is rarely possible; hence the destruc- 

 tion or removal of the sick, with thorough disinfection of the infected 

 locality, is the next thing to be done. As to the disinfectants to be 

 used, special directions are given under the various diseases, to which 

 the reader is referred. Here we will simply call attention briefly to 

 the general subject. 



Disinfection consists in the use of certain substances which possess 

 the power to destroy bacteria or their spores, or both. Those which 

 are cheapest and most available for animal diseases are ordinary 

 freshly slaked lime or unslaked in powder, chlorid of lime, crude car- 

 bolic acid, corrosive sublimate, formaldehyde gas, formalin, creolin, 

 and lysol. 



(1) Slaked lime is perhaps the most easily procured, but its disin- 

 fecting power is limited. While it is capable of destroying all bac- 

 teria in their vegetative state, it is unable to destroy spores such 

 as those of anthrax and blackleg. It is probable, however, that in 

 incrusting spores it may destroy their vitality sooner or later. It is 

 regarded as safe practice to use only spore-destroying substances for 

 the virus of those diseases of which we have no definite knowledge. 

 Nevertheless, in the absence of other disinfectants, lime is very useful. 

 It may be employed as a whitewash on wood and stone and sprinkled 

 as a dilute wash or in powder over yards, manure heaps, and over 

 carcasses before they are buried and over the ground on which they 

 have lain, to prevent other animals from carrying the infection away. 



(2) Chlorid of lime is more efficient than simple slaked or unslaked 

 lime, since it destroys spores. It is the ordinary bleaching powder 

 of commerce5 and is quite unstable; hence old preparations, unless 

 sealed, are of little value. A 5 per cent solution is sufficiently strong 

 for all spore-bearing bacteria (3 ounces in 2 quarts of water). It may 

 be efficiently applied to the walls and floor of an infected stable by 

 mixing with limewash in the proportion of 6 ounces of the chlorid of 

 lime to each gallon of limewash. The ceilings and those portions of 

 the walls which can not be reached should be disinfected by means 

 of chlorin gas liberated from the chlorid of lime by crude carbolic 

 acid. This is accomplished by making a cone of 5 or 6 pounds of 

 chlorid of lime, in the fop of which a deep crater is made for the 

 placement of from 1 to 2 pints of crude carbolic acid. The edge of 

 the crater is thereupon pushed into' the fluid, when a lively reac- 

 tion follows. Owing to the heat generated, it is advisable to place 

 the chlorid of lime into an iron crucible and to have nothing inflam- 

 mable within a radius of two feet. The number and location of 

 these cones of chlorid of lime depend on the size and structure of 

 the building to be disinfected. As a rule it may be stated that chlorin 

 gas liberated from the above-sized cone will be sufficient for disin- 



