266 BACTERIOLOGY. 
killed—viz., at 55° C. in one hour, at 60° C. in fifteen 
minutes, at 65° C. in fifteen minutes, at 70° C. in ten 
minutes, at 80° C. in five minutes, and at 95° C. in one 
minute. One reason why they appear to withstand in 
milk high temperatures for a longer time than given in 
the above figures is, ag pointed out by Theobald Smith, 
that when heated in a test-tube the cream which rises 
on heating is exposed on its surface to a lower tem- 
perature than the rest of the milk as this contains 
many bacteria some of them lato less heat 
than those in the rest of th , 
The resisting power of t 
cal disinfectants is considera' great as it 
is apt to appear, for, as in bacillus is 
usually protected by mucus or cell protoplasm from 
penetration by the germicidal agent. It is not always 
destroyed by the gastric juice in the stomach, as is 
shown by successful infection experiments in susceptible 
animals by feeding them with tubercle bacilli (Baumgar- 
ten and others). They are destroyed in sputum in six 
hours or less by the addition of an equal quantity of a 
3 per cent. solution of carbolic acid, and in about one 
hour by an equal amount of a 5 per cent. solution. 
Bichloride of mercury is unsuitable for the disinfection 
of sputum unless used in very strong solutions (1 : 500). 
From recent experiments by Yersin upon pure cultures 
of the bacillus it appears that tubercle bacilli were killed 
by a 5 per cent. solution of carbolic acid in thirty sec- 
onds; by 1 per cent. in one minute; absolute alcohol, 
five minutes; iodoform-ether, 1 per cent., five minutes; 
mercuric chloride, 1 : 1000 solution, ten minutes. Salt- 
ing and smoking are said not to destroy the virulence 
of tuberculous meat (Forster). 
