280 EXPERIMENT STATION RECORD. [Vol.38 



Principles and practice of milk hygiene, L. A. Klein (PhiladclpMa and 

 London: J. B. Lippincott Co., 1917, pp. X+S29, pis. 5, figs. S3).— This book, 

 which is inteucled primarily for a text for students in milli hygiene, treats of 

 thj physiology of milk secretion ; the properties of colostrum and its detection ; 

 the physical and chemical properties of milk, its microscopic appearance, the 

 ferments and enzyms it contains, and the bacteria with which it may be con- 

 taminated ; defects in the consistency, odor, taste, and color of milk due to 

 nonbacterial causes; diseases of cattle transmissible to man through milk, or 

 which may make milk harmful to man, and diseases of man transmissible 

 through milk; dairy inspection; pasteurization; and methods of examining 

 milk. Tlie appendix gives methods and standards for the production and dis- 

 tribution of certified milk. 



Safe milk. — An important food problem, E. A. Sweet {Pub. Health Rpts. 

 [U. S.], Sup. SI (1917), pp. 24). — A general discussion of the production and 

 handling of sanitary milk, the topics dealt with being the composition of milk, 

 abnormal qualities of milk, milk adulteration, accidental impurities, bacteria 

 in milk, and milk-borne diseases and their prevention. 



Report of an investigation into the hygienic quality of the milk supplied 

 to babies attending certain schools for mothers, with suggestions to those 

 responsible for the feeding of children, W. Buckley {Nat. Clean Milk Sac. 

 [London], [Pnb.'], No. 10 {1917), pp. 18). — Results are given of the examina- 

 tion of samples of milk from 27 dairymen in London supplying milk for bottle- 

 fed babies. The bacterial content of these milk samples varied from 98,000 to 

 104,300,000 per cubic centimeter. Organisms of the Bacillus coll group were 

 present in all the samples examined, and tubercle bacilli were found in two of 

 the samples and in one sample of certified milk. 



Suggestions are given for the improvement of the milk supply of cities in 

 Great Britain and Ireland. 



Variations in cream tests. — Differences between butter and butter fat, 

 W. A. Wilson {Saskatchewan Dept. Agr. Bui. 43 {1916), pp. 15, figs. 2).— This 

 bulletin gives information concerning the variation of the cream test and the 

 difference between butter and milk fat. 



In seven tests, in each of which mixed milk was divided into three lots and 

 separated at temperatures of 98, 80, and 70° F., all other conditions being 

 uniform, the fat content of the cream increased as the temperature of the milk 

 was decreased. In one of the tests 24 per cent cream was separated from milk 

 at a temperature of 98° and 35 per cent cream at a temperature of 70°. The 

 fat content of the skim milk was higher for the cooler lots of milk. 



Six lots of milk were separated at speeds of the separator crank varying 

 from 50 to 62 revolutions per minute, the separators being adjusted to a correct 

 speed of 60 revolutions per minute. In these tests the fat content of the cream 

 decreased with the speed of the separator. In one trial the test dropped from 

 41 to 22 per cent when the crank speed was reduced from 60 to 50 revolutions 

 per minute. 



In another series of seven trials cream tests ran frcm 1 to 5 per cent higher 

 when the receiving can of the separator was almost empty than when the re- 

 ceiving can was full. Other causes for variation in cream tests are mentioned. 



In order to demonstrate how the weight of butter churned can be increased 

 when quality is not considered, a series of five churnings was made, in each of 

 which one lot of cream was divided into two parts of equal wei<jht and churned 

 under different conditions. In one test 26 lbs. of 41 per cent cream, at a tem- 

 perature of 55°, was churned in 25 minutes and made 8 lbs. 2 oz. of butter and 

 17 lbs. 4 oz. of buttermilk which tested 0.15 per cent fat. The other lot of 



