BUREAU OF AXIMAL INDUSTRY, 121 



462,975 tests. This is moic than double the number of outfits and 

 the amount of suppUes sent to field inspectors in 1916. 



A method for preparing and testing pure arsenious oxid has been 

 successfully worked out and the details published in the Journal of , 

 Industrial and Engineering Chemistry (vol. 10, p. 522). 



There has been devised also a method for the preparation of solu- 

 ble starch which is used as an indicator in testing arsenical dipping 

 baths. This new method appears to be as satisfactory as the one 

 previously in use and at the same time less expensive. 



A study has been made of the effect of sodium sulphid on anthrax 

 spores, and it has been found that a 5 per cent solution, while ineffec- 

 tive in 5 hours, destroys the spores in 18 hours. A 10 per cent solu- 

 tion was ineffective in 2 hours but effective in 4 hours. The presence 

 of organic material, such as blood serum, did not appear to influence 

 the results. 



DISINFECTION OF HIDES. 



Studies of methods for disinfecting hides and tannery effluents 

 have been continued. Further studies of the effect of heat upon 

 anthrax spores in soak water from hides and skins show that as a rule 

 momentary heating at 100° C. is sufficient to destroy anthrax spores, 

 but in the case of certain higlily resistant strains the organisms were 

 not destroyed; one or two spores out of 500 or 600 in the heated 

 effluent surviA'ed heat at 100° C. for 1 minute. Three minutes' 

 heating at 100° C. was sufficient to insure sterifity. Heating at 93° 

 C. for 15 minutes destroyed the spores in all instances. Heating at 

 80° C. for 30 minutes greatly diminished the number of spores but 

 did not destroy all of them. When the effluent was first treated with 

 chlorin in the proportion of 50 parts per million and then heated 

 at 80° C. for 30 minutes, all the spores were destroyed. Further 

 experiments with chlorin for disinfecting soak water from hides 

 showed that the amount required varied from 250 parts to 400 parts 

 per million, the amount varying in proportion to the organic matter 

 present. 



In the disinfection of dried hides the work was confined entirely to 

 the use of solutions of hydrochloric acid and common salt. In labora- 

 tory experiments it was found that 1 per cent of actual hydrochloric 

 acid plus 10 per cent of sodium chlorid with 40 hours' exposure, and 

 2 per cent actual hydrochloric acid plus 10 per cent sodium clilorid 

 with 20 hours' exposure, rendered infected pieces of hide noninfec- 

 tious for animals, although the spores were not always entirely de- 

 stroyed. The number remaining alive, though noninfective, was 

 extremely small when compared with the number used to infect the 

 hides. 



In principle it may be said that hides and skins can be subjected 

 to treatment with hydrochloric acid and salt without injury, but it is 

 necessary to adapt the method of disinfection to the common tannery 

 practices. On a large scale in a tannery injury may be done to hides 

 and skins by the hydrochloric acid and salt solutions if neutralization 

 and washing are improperly carried out. The process appears to be 

 reasonable in cost, although its relative economy in comparison with 

 other processes when used on a large scale has not yet been ascertained. 



97335°— AGR 1918 9 



