78 AIDS TO BACTERIOLOGY 



Disinfection. No danger is apprehended from the 

 handling of wools from Australasia and the Argentine, 

 but precautions are necessary when dealing with horsehair 

 from China, Siberia, and Russia, and with Persian wool. 

 While the vegetative forms are quickly killed by heat and 

 disinfectants, 5 per cent, phenol acting for at least twenty- 

 four hours is required for the destruction of the spores, 

 and the disinfection of hides, hair, and wool is therefore 

 difficult. For hides and skins the use of formaldehyde is 

 impracticable, since it so injures the consignments as to 

 prevent them being turned into good leather. Legge 

 thinks it doubtful if there is any way in which hides to 

 be afterwards tanned can be effectively disinfected. 



Constant Ponder concludes the best method for de- 

 stroying the infection on hides to be that devised by 

 Seymour Jones. The process involves treating the hides 

 for twenty-four hours in a soak containing 1 per cent, of 

 formic acid and 0-02 per cent, mercuric chloride, and 

 then transferring them to the ordinary brine pit. This 

 does not interfere with the subsequent processes involved 

 in transformation into leather. Hewlett found the pro- 

 cess to be satisfactory provided the strength of the solution 

 was doubled or trebled when dealing with horsehair. 

 Forty-eight hours' exposure to a solution containing 2 per 

 cent, hydrochloric acid and 10 per cent, sodium chloride 

 (Schattenfroh method) is also satisfactory (Lancet, August 

 7, 1915). 



Webb and Duncan's experiments seem to show that, 

 leaving out of consideration white or grey hair, which is 

 liable to change colour, no injurious effect is produced on 

 horsehair by steam disinfection, provided the temperature 

 does not exceed 218 F. a comparatively low tempera- 

 ture for efficient disinfection. Legge concludes that, to 

 secure certain destruction of all anthrax spores in horse- 

 hair, absolute reliance cannot be placed on either steam 

 disinfection (within the limits in which it can be applied) 

 or simple boiling. 



In the Home Office Regulations in respect of processes 

 involving the use of horsehair from China, Siberia, or 

 Russia, no manipulation except opening or sorting is 

 allowed until the hair has undergone disinfection. Dis- 

 infection may be accomplished either by exposure to a 

 temperature of not less than 212 F. for at least half an 



