HARMFUL BACTERIA 
65 
but No. 4, the one in which was put the corrosive 
sublimate. This is a poison to human beings when 
taken internally. 
No. 1 is open to air and dust and in time will be¬ 
come sour or undergo fermentation. If left long 
enough the milk may putrify. 
No 2 is closed to dust but not to air. However, 
no pains was taken to free the bottle or plug from the 
dust which was on them or in the contents, so in time 
this will become sour. 
No. 3 has all the conditions of No. 1 except warmth, 
which is favorable, and light, which to some dust 
plants is unfavorable. It should not spoil or sour as 
quickly as No. 1. 
No. 4 has been treated by a chemical which is poi¬ 
sonous and should kill the dust-plants present. This, 
if strong enough to kill, is a disinfectant. If only 
strong enough to prevent or retard growth for a while 
it would be an antiseptic. There should be no change 
in No. 4. 
No. 5 will have been sterilized, that is, all life within 
liquid, or bottle, killed by the steaming process. 
The first steaming is expected to kill all the growing 
or vegetative forms then present. It may not be enough 
to kill any spores' that are there. These will be en¬ 
couraged to grow by the greater heat, but on the sec¬ 
ond day they will have developed into 'the ordinary 
growing form and the steaming should kill them. 
That sterilization may be assured and any possibly 
Intermittent 
Sterilization 
