DAIRY FARMING DAIRYING. 571 



and when the temperature was maintained at 11° all the fat globules of the 

 cream were half solidified. When the cows were kept in their sheds somewhat 

 higher figures were obtained. It is possible in certain cases (e. g., by feeding 

 beets to the cows) to obtain solidification even at a temperature of from 18 to 

 20°. As a rule, the critical temperature for the change in the state of the fat 

 globules is to be found between 12 and 16°. 



" In cream in which the volume of the fat globules was in normal relationship 

 with the temperature at the beginning of churning, no solidification of the 

 globules was produced during the process of churning. This has been proved 

 a number of times. After a preliminary cooling for 21 hours at a temperature 

 of 11° it is possible to find a slight continuation of the solidification of the 

 globules during churning. This, however, was more noticeable than when the 

 cream was cooled to 13° ; in the case of cooling to 16° the continuation of 

 solidification was still less perceptible. It may be concluded from this that 

 fatty matter kept at a temperature favorable to acidification undergoes very 

 little change in volume. The prevailing opinion that most of the globules be- 

 come solidified during churning is, therefore, in nowise confirmed. 



" Before churning, it is necessary to try and solidify the fat globules as 

 much as possible, for cream containing solidified fat globules can be churned 

 at a higher temperature. In this way it is possible to avoid all trouble caused 

 by changes in the condition of the fat globules during churning. The degree 

 to which the temperature is reduced has a more marked effect upon the change 

 in condition of the globules than the duration of the cooling. Thus it has been 

 found that after a preliminary cooling for four hours at a temperature of from 

 6° to 8° solidification was more rapid than after a 21 hours' treatment at 11°. 

 Cooling to a low temperature (6°) is especially to be recommended in autumn. 



" These results explain the success obtained with the density method of 

 Swartz. If cream with a uniform content of fatty matter, but from different 

 cows, is cooled for 21 hours at a temperature of 12° a varying amount of 

 dilatation is observed in the fat globules when the cream is subsequently heated. 

 The maximum dilatations were 188 units, the minimum 125 units, in 10,000 units 

 of volume. The nature of the cow's feed has a considerable effect upon the 

 dilatation of the fat globules, as many experiments have proved. In the same 

 way, any change in the animal's mode of life such as the descent from the alpine 

 pastures to their winter quarters, or vice versa, is also clearly demonstrated 

 by the dilatometer. 



*' The iodin value of the fat globules is in direct relationship with the solidify- 

 ing power, which shows that combinations of oleic acid have a preponderant 

 effect on solidification. There are, however, some exceptions in cases where 

 the iodin value is very small and where consequently there is very little dilata- 

 tion. A cream containing globules which only dilated to a small extent gave 

 in many experiments a soft butter, whereas in cases where the dilatation was 

 considerable the butter produced was hard. In every case where the iodin 

 value corresponded imperfectly to the dilatation, this latter corresponded better 

 to the consistency of the butter." 



Inexpensive appliances and utensils for the dairy, W. D. Nicholls {Kenr 

 tucky Sta. Circ. 6 {1915), pp. 15-31, flgs. 9). — This circular describes various 

 kinds of inexpensive homemade steam sterilizers and a new-style sanitary 

 milk pail. 



Laboratory guide in market milk, H. E. Ross {Ithaca, N. Y.: Carpenter 

 and Co., 1915, pp. 65, flgs. 2). — This book is designed for the use of students 

 in dairy laboratories. 



The present status of the pasteurization of milk, S. H. Ayees ( U. S. Dept. 

 Agr. Bui. 31,2 {1916), pp. 16, fig. i).— This bulletin discusses the value of pas- 



