INFECTIOUS DISEASES OF CATTLE. 375 



former ou fresh ground. This is rarely possible, hence the destruction 

 or removal of the sick, with thorough disinfection of the infected local- 

 ity, 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 in solution which 

 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, chloride of lime, crude carbolic acid, and mercuric 

 chloride or corrosive sublimate. 



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

 fecting power is limited. While it is capable of destroying all bacteria 

 in their vegetative state, it is unable to destroy spores such as those of 

 anthrax and black quarter. It is probable, however, that in incrust- 

 ing 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. Neverthe- 

 less 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 wasli 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) Chloride of lime is more efficient than simple slaked or unslaked 

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

 commerce, 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). 



(3) Crude carbolic acid. The ordinary purified carbolic acid is too 

 expensive to be used on a large scale, and the crude product is a very 

 good substitute. This is made more powerful by mixing with it an 

 equal A'olnme of commercial sulphuric acid. While the sulphuric acid 

 is being added to the crude carbolic acid much heat is evolved, and if 

 the glass jar in which the two are mixed together is placed in cold 

 water the resulting product is said to hare a higher disinfecting power. 

 The mixture is added to enough water to make a 5 per cent solution 

 (almut 3 ounces to 2 quarts of water). This is strong enough for all 

 purposes. It may be kept in wood or glass but not in metal, owing to the 

 corroding action of the acid. It should be applied freely on woodwork 

 and on infected floors. It must be borne in mind that it may be inju- 

 rious to the hands, and to the feet of animals which arc compelled to 

 walk in it. In most cases where ita application becomes desirable 

 and this rule Hhould apply to all disinfections the disinfected stables, 

 stalls, etc., Hhould remain vacant as long as possible before cuttle are 

 again put in. 



(4) Mercuric chloride or corrosive sublimate is a powerful disinfe.e- 



