on Milk and Milk-Products. 
393 
that the milking is done in a pure atmosphere, the danger of 
organisms entering the milk is reduced to a minimum. Milk 
treated in the manner described has been found to keep fresh 
and sweet for several weeks. If this system must be pronounced 
as unworkable in the daily practice of dairying, it no doubt gives 
valuable hints which ought to receive careful consideration. 
The utmost cleanliness with regard to the cows, and more 
especially their udders, as well as all the vessels with which the 
milk comes in contact, is of the greatest importance in keeping 
micro-organisms in check. It is a precaution deserving full 
attention not to collect the first stripping from each teat, but to 
milk it into the hollow of the hand, and taste it, as is done in 
some dairy districts. All vessels should be cleansed with boiling 
water, and finally, if possible, a jet of steam directed into them. 
To avoid the milk coming into contact with the air is a prac- 
tical impossibility, and even under Pohl's patent system it is 
not altogether excluded. The first care then must be to keep 
the air as free from impurities as possible. As, however, even 
in the purest air at our disposal, micro-organisms are present, 
the question arises, how can their action be limited, or pre- 
vented ? 
Destroying ferments, or at least preventing their develop- 
ment, is the object of all the different processes of disinfection 
and preservation. These can be divided into two groups — those 
which are based on the addition of certain chemical disinfect- 
ants, and those in which the application of low or high tem- 
peratures is relied upon. 
Employing chemicals for the purpose of preserving milk is, 
upon the whole, objectionable. The most powerful disinfect- 
ants, containing acids and compounds of the heavy metals, are 
absolutely excluded because of their decomposing action on 
milk, and their effect upon the human body. Others, such as 
thymol and benzoic acid, are not suitable on account of their 
imparting to milk an unusual smell, or as giving a taste, e.g. 
salicylic acid, when added in quantities sufficient to have any 
appreciable preservative efl'ect. 
Perhaps the least objectionable of all preservatives recom- 
mended for milk is boracic acid and its various preparations, 
the effect of the latter depending on, and being equivalent to, the 
quantity of the pure acid they contain. But even the addition 
of boracic acid is of comparatively little use, and at the same 
time cannot be considered altogether harmless. The quantity of 
the acid which can be added to milk without impairing its 
taste is relatively small, though large enough to interfere with 
the assimilation of food in the human system when continuously 
taken. Moreover, the addition of the preservatives in question 
