144 BACTERIA IN DAILY LIFE 



80 grains of this material were present in a pint of 

 milk sold to their inspector. It is pointed out that 

 as long as preservatives are permitted there is 

 no guarantee against the addition of excessive 

 amounts to milk, and that evidence has been 

 obtained pointing to an injurious effect of boracised 

 milk upon the health of young children. The 

 Committee report that in Denmark the use of 

 preservatives is strictly prohibited, and the pro- 

 hibition is strongly enforced ; neither are preserva- 

 tives permitted in Belgium. 



The application of heat to milk is, in fact, the 

 only advisable and reliable method for rendering 

 it free from germs, but a great deal depends upon 

 the manner in which the heat is applied and the 

 cleanly condition or otherwise of the milk employed. 



The difficulties which have to be overcome in 

 producing efficiently sterilised milk are due, in the 

 first place, to the remarkable power of resisting heat 

 which characterises not only some disease germs, 

 but also some of the microbes which are par- 

 ticularly partial to milk ; secondly, to the sensitive- 

 ness of milk to heat, as exhibited by its alteration 

 in taste and other respects through exposure to 

 high temperatures. 



To overcome these difficulties many ingenious 

 pieces of apparatus have been devised, based upon 

 a process originally introduced by Pasteur for pre- 



