52 SPREAD OF CONTAGION 



the ova of lice. This method should, where practicable, be 

 adopted in the case of rugs and other articles used by 

 infected animals. 



Conveyance of contagium by attendants is prevented by 

 sprinkling their clothes and boots with weak carbolic solu- 

 tions. After handling animals affected by contagious 

 disease, or making post-mortem examinations of such 

 subjects, the hands should be cleansed first with soap and 

 water, and then washed with a 4 per cent, solution of car- 

 bolic acid, or with a solution of 12-15 grains corrosive sub- 

 limate to a quart of water, which very effectually destroys 

 any adhering bacilli. 



So soon as the premises in which animals affected with 

 contagious disease have lived can be emptied, more thorough 

 disinfection should be carried out. To this end, doors and 

 windows having been closed, formic aldehyde, chlorine, or 

 sulphurous acid should be freely evolved, and the place kept 

 shut for several hours. Walls, floors, and woodwork should 

 subsequently be scraped, and washed with corrosive sublim- 

 ate solution or other disinfectant. 



Different disinfectants are suitable for different purposes. 

 For putrefying or contagious matters mixed with water, 

 the best are mineral salts, of which the most effective and 

 cheapest are corrosive sublimate ; zinc chloride, in the 

 familiar form of Burnet's fluid ; and iron chloride, or 

 formalin. For sewage disinfection, or where there is much 

 water, aluminium sulphate, followed by lime, can be recom- 

 mended. Sulphites promptly remove smells, and are most 

 effectual when conjoined with the tar acids. The mixture 

 of sodium sulphite and carbolic or cresylic acid, although 

 effectual for deodorising, has a feeble power in preventing 

 the putrefaction of night soil, for which potassium perman- 

 ganate is most useful. Common salt, although ineffectual 

 in checking decay when once established, or in neutralising 

 bad smells, is a cheap preserver of many animal substances. 

 It preserves and disinfects skins. Iodine is volatile and 

 penetrating. It is used in many sick-rooms and hospitals, 

 conveniently dissolved in the light diffusible pentane. The 

 solution contains 20 grains to the ounce ; an ounce suffices 

 for four cubic feet of space ; distributed by a spray pro- 



