312 EXPERIMENT STATION EECORD. 



Ilojiltli Series, edited by (L S. Grahara-Smitli and J. E. Purvis, is said to fill 

 these requirements, and its contents are as follows : General methods for the 

 isolation and identification of indicator organisms, water, soil and. sewage, shell- 

 fish, milk, modified milk and milk products, the bacteriology of meat and meat 

 products, air, and the determination of antiseptic and germicidal power. An 

 appendix dealing with the composition of the culture media is included. 



Fatty foods: Their practical examination, E. R. Bolton and C. Revis 

 (I'hiludclpJtia, I'JIS pp. X+STl, pis. 8, figs. 36). — This handbook is intended 

 for analytical and technical chemists and deals with general and si)ecial methods 

 for the examination of foods and feeding stuffs containing fats. The contents 

 are as follows : Beef fat, lard, butter, margarin, and ghee ; vegetable oils and 

 fats — special tests for oils and fish and marine animal oils; rancidity; cocoa, 

 chocolate, and milk chocolate; feeding stuffs — methods of analysis and calcu- 

 lation of rations; and milk — analysis and examination for use in margarin, 

 pasteurization, cleanliness and bacteriological condition, and cream and sepa- 

 rated milk. 



Methods for the biological examination of milk, J. Bauer (Die Methodik 

 dcr Biologischcn Milch untersucJiung. Stuttffitrt, 1913, pp. XI-\-112, figs. 15). — 

 This small book deals principally with biological methods for examining milk, 

 under the headings of methods for determining the animal from which the milk 

 originates; determining heated milk; and determining the sanitary condition 

 of milk. It is said to be the first book of its kind. 



A method for the determination of fat in milk (nephelometric method), 

 W. R. Bloor {Jour. Amer. Uhcm. Hoc, 36 {191Jf), Xo. 6, pp. 1300-l.:^OJf).—" The 

 procedure is as follows : One cc. of the milk, measured with an accurate pipette, 

 is run slowl5^ and with stirring into about 80 ce. of an alcohol-ether mixture 

 (containing 3 parts of redistilled alcohol and 1 part of redistilled ether) in a 

 100 cc. graduated flask. (The measurement may be checked by determining the 

 weight of the added milk.) The mixture is raised to boiling by immersion in 

 a boiling water bath, cooled to room temperature, made up to 100 cc. with the 

 rlcohol-ether, shaken, and filtered. The filtrate is clear and almost colorless. 



" For the determination, 5 cc. of the solution is run from a pipette, slowly 

 with stirring, into 100 cc. of distilled water in a beaker, producing a slightly 

 opalescent colloidal solution. The point of the pipette must be kept below the 

 surface of the liquid during the outflow. A similar solution is prepared with 

 ' 5 cc. of the standard fat solution. To the standard and to the test solutions 

 are added, simultaneously, 10 cc. portions of dilute (10 per cent) hydrochloric 

 iicid and, after stirring, the solutions allowed to stand for five minutes, after 

 which they are transfen-ed to the comparison tubes of the uephelometer [E. S. 

 R., 30, p. 410]. 



" For the comparison, the two tubes, filled to the same height with the solu- 

 tions, are placed in the nephelometer with the standard tube always on the 

 same side. If bubbles appear in the walls of the tubes they are removed by 

 inverting two or three times. The movable jacket on the standard side is set 

 at a convenient point, generally 50 mm. (Richards' nephelometer), and com- 

 parisons made by adjusting the jacket on the test solution until the images of 

 the two tubes show equal illumination. At least five readings are taken, alter- 

 nately from above and below, and the average taken as the reading. This read- 

 ing is cori'ected from the calibration curve of the instrument and the fat value 

 of the milk calculated from the correctetl rending. 



"The standard solution is an alcohol-ether solution of pure triolein, made 

 with freshly distilled absolute alcohol and pure dry ether, of which 5 cc. con- 

 tains about 2 mg. of fat." See also a previous note (E. S. R., SI, p. 610). 



