Apr. IS, 191S 



Disinfection of Hides 



69 



The results of the above experiment indicate that mercuric chlorid, i 

 to 5,000, plus I per cent of formic acid, is efficient where mercuric chlorid 

 alone is not and that the hydrogen-sulphid solution should be used to 

 neutralize the disinfectant before putting the rods into subculture tubes. 

 The result after 48 hours' exposure to 5 per cent of phenol indicates the 

 resisting power of the anthrax spores. The next experiment consisted 

 of short exposures with the addition of defibrinated blood. This experi- 

 ment was intended to test the efficiency of the method of disinfecting 

 hides prescribed in Circular No. 23 of the Treasury Department, which 

 consisted in immersion of hides for half an hour in a solution of mercuric 

 chlorid, I to 1,000. 



The technique was similar to that described for experiment i, except 

 that all rods were washed with hydrogen-sulphid solution and defibrinated 

 blood was added so as to make up 10 per cent of the volume of the dis- 

 infectant in each tube. The results are given in Table II, experi- 

 ment 2. 



Experiment 2 indicates that anthrax spores are not destroyed in the 

 presence of defibrinated blood by mercuric chlorid, i to 1,000, without 

 formic acid, or by mercuric chlorid, i to 5,000, plus i per cent of formic 

 acid, even with an exposure of two hours. 



An experiment with stronger dilutions of mercuric chlorid plus formic 

 acid was now tried. Defibrinated blood was added in the proportion of 

 10 per cent of the total volume. (See Table II, experiment 3.) 



TabIvE II. — Germicidal efficiency of mercuric chlorid, with or without formic acid, by 

 the rod method, with the addition of defibrinated blood « 



EXPERIMENT 2 



EXPERIMENT 4 



Mercuric chlorid (i:i,ooo) 



^Mercuric chlorid (i:s,cx)o)+foniiic acid (i E>er cent). 

 Control rod 



C) 



No growth. 

 Do. 



Growth. 



a Subculture tubes incubated one week. Rods washed with hydrogen-sulphid solution. 

 *> Not exposed. 



