'New Yoek Agricultukal Expekiment Station. 133 



cream by exposure to this temperature, heating to 60°C. (140°F.) 

 for 30 minutes is now coming more into favor. According to the 

 researches of Dr. Theobald Smith,^ 15-20 minutes at 60° C. 

 (146°F.) is sufficient to kill the tubercle bacillus provided the milk 

 is kept stirred so as to prevent the formation of a pellicle at the 

 surface. Higher temperatures and a shorter time would give the 

 same result, but when the temperature of 70°C. (158°F.) is 

 passed the milk takes on a disagreeable, cooked taste. This is 

 largely due to an oxidation of some of the components of the hot 

 milk and it is possible that in the future a way may be found of 

 avoiding this flavor. 



The main feature in the discontinuous process is the removal 

 of the danger from disease and this applies not only to tubercu- 

 losis but to all other germ troubles which are liable to gain access 

 to the milk before it is heated. The keeping quality of the milk 

 is much improved, especially if proper attention is given to keep- 

 ing it cool after treatment and the effect of the carelessness and 

 lack of cleanliness which are often prevalent at the barn is in a 

 measure removed. A very commendable practice exists of pass- 

 ing the milk through a separator and remixing the milk and 

 cream before pasteurization. This removes a large part of the 

 hair, excrement, etc., which is so common in the ordinary milk 

 supply of cities. 



This method of handling milk for immediate consumption is in 

 successful operation in a number of cities on a large scale. It 

 has much to commend it and when done in a large way it does not 

 increase the cost of production more than a small fraction of a 

 cent a quart. 



THE CONTINUOUS OR DANISH SYSTEM. 



When the Danish system of butter making was introduced into 

 America pasteurization came as a necessary part of it, but in this 

 case the principal object was the fitting of the cream to receive 



3 Journal of Experimental Medicine, 4: 217-233 (1899). 



