Pasteurisation. 53 



common : one is the aforesaid burning or scorching of 

 the milk, and another the great insecurity of attaining 

 the desired degree of heating for all the milk passed 

 through the apparatus. As the injection of the milk 

 was continuous it was unavoidable that some part of the 

 milk would at times rise and find the exit without 

 having attained the prescribed degree of heat. As 

 we may suppose all such milk heated to 1(5.") or 170 

 acquired the taste of boiled milk, a defect which, it is 

 safe to say, has hardly a chance to be overcome. The 

 great heat that has to be kept up on the metal sides 

 of the copper cylinder containing the milk is one of 

 the great defects of all of our present pasteurizing 

 machines, and it is certain that this must be remedied 

 before pasteurization will become an operation of uni- 

 versal practice. After what has now been said there 

 would be justice in contending that the present pas- 

 teurizing apparatus will be even less successful if 

 temperatures of not more than 17() F. can be applied. 

 This will hold good only for the present apparatus - 

 in other words, all these apparatus have a defect, and 

 a signal defect at that, which involves the scorching 

 before mentioned. This great defect is that the milk 

 is heated for too short a time and that it remains 

 inside of the apparatus for too limited a duration, 

 consequently necessitating a comparatively excessive 

 heating at the sides of the milk to attain an enhanced 

 keeping quality. 



From this reflection and from the observation that 

 the u boiled " taste of milk is already noticeable at 



