DAIRY FARMING DAIRYING. 83 



Milk testing at factories, <i. S. Thomson (Jour. Af/r. and Ind. South Australia, 

 4 [1901), No. 7, pp. 560-5GS). — In an experiment of covering milk cans with cloth 

 kept moistened, it was found tliat the milk arrived at the factory several degrees 

 cdoler and with a lower acid content by several points. 



A source of error in some turbine testers, F. W. Woll ( Wisconsin Sta. Rpt. 

 I!i00,]>p. 7G-S1) .—This lias been alistracted from another source (E. S. R., 11, p. 1083). 



Influence of temperature on tests of skim milk by the Babcock test, E. H. 

 Kakkington []Vi>i<-oHxin sta. Rpt. 1900, pp. S1-S6) . — The fat content of skim milk 

 w as determined by gravimetric analysis and by steam turbine testers at 140 and 200° F. 

 in 10 comparative tests. The average results by the 3 methods were, respectively, 0.08, 

 0.06, and 0.03 per cent. "In every case the tests were higher when made in the 

 tightly-closed tester and heated to about 200° F. than they were when tested in the 

 machine having an ojiening in the cover and whirled at about 140° F. In some 

 cases twice as much fat was shown in the hot test bottles as in the others. . . . 

 Tests of skim milk made with 20 cc. of acid and whirled at a high speed in a machine 

 heated to about 200° F. give results nearer those obtained 1)v gravimetric analysis 

 than are obtaine<l l)y any (jther method." 



The estimation of fat in sweetened condensed milk by the Babcock test, 

 E. H. Farkington {]Vi.^cuii.^in Sta. Rpt. 1900, pp. S6-S9). — This has l)een abstracted 

 from another source (E. S. R., 12, p. 307). 



Testing for pasteurized milk, A. Bernstein (Ztscltr. Fleiscli u. M'dchhyg., 11 

 {1900), Nu. o, ])j). SO, SI). — The following method is given for estimating the degree 

 to which milk has l)een heated: To 50 cc. of the milk 4.5 cc. of a normal solution of 

 acetic acid is added, slightly shaken until the milk has coagulated, filtered, and the 

 clear filtrate heated. If the original milk has not been pasteurized, a heavy precipi- 

 tate of albumin will form. The higher the milk has been heated, up to 90° C, the 

 smaller will be the pret-ipitate. Above that no precipitate will occur. 



Thermal death point of tubercle bacilli under commercial conditions, H. L. 

 Ri'ssELL and E. G. Hastings {Wisconsin Sta. Rpt. 1900, pp. 147-170) . — Standards 

 recommended for the pasteurization of milk for the destruction of tubercle bacilli 

 are given and discussed, and investigations conducted for the purpose of retesting 

 some of the more recent work (E. S. R., 12, p. 1091) under commercial conditions 

 are reported. 



In 5 series of experiments milk was inoculated with pure cultures of the tubercle 

 bacillus and heated at 60° C. in a commercial rotary pasteurizer. The time of heat- 

 ing in the different tests varied from 5 to 45 minutes. Control samples were 

 unheated. The vitality of the bacilli was tested by intraperitoneal injections into 

 guinea pigs. The results of the tests, including post-mortem notes, are given in 

 detail. "The conclusions from these series indicate that a temperature of 10 min- 

 utes at 60° C. (140° F. ) is sufficient to destroy the vitality of the tuliercle organism 

 so completely that large doses inoculated in the most susceptible portion of a very 

 susceptible animal (guinea pig) fail to jjroduce any development of the disease, 

 while unheated samples of milk and those exposed to 60° C. (140° F. ) for 5 minutes 

 produced the disease without exception." 



In 2 series of experiments a comparison was made of heating milk at 60° C. in the 

 commercial pasteurizer and in open bottles placed in a water bath. In the latter 

 case the milk remained in a (juiescent condition and was exposed to the action of 

 the air which j)ermitted a film to form on the surface. "Where the milk was 

 exposed in a (piiescent condition, as in a glass tube or bottle, the tuliercle l)acilli 

 were more resistant than where the milk was in a closed receiver and agitated. 

 While all tubercular organisms were destroyed in the commercial pasteurizer in 10 

 minutes, neither an exposure for this j)eriod nor for 15 minutes sufficed to destroy 

 the same lot of organisms when the iiulk was treated in a quiescent condition at the 

 same temperature in vessels to which the air had more access. . . . 



