421 



determinations, by means of tlKj lactoeiitc, of the tat in sour milk so 

 treated, showed very nearly the same percentage as had been contained 

 in the fresh sample. A slight error was noticed, however, sour milk 

 2 days old showing an average decrease of 0.05 per cent in fat as com- 

 pared with the fresh sami)le. A correction was tlierefore made by add- 

 ing 0.05 to the results obtained by the lactocrite. It is recommended 

 to make the lactocrite test directly after the addition of ammonia. It 

 is essential to accurate results to add the ammonia to the whole volume 

 of sour milk in the vessel in which it soured, instead of attempting to 

 take an average sample from this, and it is therefore necessary to know 

 the exact volume of the sour milk. j 



Testing milk by electricity, Dohrmann {MolJi. Ztg., 1891; abs. in 

 Vtljahressch. it. Ghem. d. Kalir. u. GeiiKSfuntl., 6 {18.91), p, 13). — The test 

 depends upon the fact that when a weak electric current is conducted 

 through a column of milk, changes are induced in the strength of the 

 current which can be measured by a galvanometer. It is claimed that 

 the test furnishes reliable indications as to whether milk has become 

 sour or has been watered. The apparatus consists of a tube through 

 which the milk runs, intercepting a weak electric current which is in 

 connection with a galvanometer, and is adjusted for normal milk at 10° 

 0. A deflection of the needle of the galvanometer to the left indicates 

 sour, and to the right watered milk. The instrument is so arranged 

 that tests can be rapidly executed, a sample of milk being taken auto- 

 matically fi'om each can, which is cooled to 10° C. by passing through 

 a cooler and then run directly through the column. The accuracy of 

 the apparatus in case of watering has been questioned. 



The eflFect of centrifugal action on the distribution of bacteria 

 in milk, Scheurlen {Arh. a. d. Kais. Ges. Amt, 7, pp. 3G9-282; abs. 

 in Ghem. GentralbJ., 1891, part 2, p. 581, and Milch Ztg., 20 {1891), 

 p. 851). — After proving that treatment in a centrifuge did not destroy 

 the vitality or virulence of bacteria, the author found further that 

 organisms not capable of motion (antlirax bacilli and spores, Prodigiosus, 

 Staphylococous aurens, and tuberculosis bacilli), as well as forms capable 

 of locomotion (il/^^a//<eriw;», bacteria causing red milk, Proteus vulgaris, 

 and typhoid fever bacilli) when suspended in water gradually sank to 

 the bottom of the vessel if allowed to stand quietly in it from 1 to 4 

 days, and were partially thrown outward by centrifugal action. Proteus 

 mirabilis and Asiatic cholera spirilli were not separated bj" this treat- 

 ment in a centrifuge, nor did they sink to the bottom after standing. 

 Tests of cream, skim milk, and dirt from a separator showed that wliile 

 a considerable number of the bacteria had been separated in the dirt 

 the cream contained many more than the skim milk. A control lest 

 made by whirhng a tube of milk in a hand centrifuge showed likewise 

 that the larger proportion of the bacteria had been separated with 

 the cream. The author concludes that in the creaming of milk, either 

 137iS— Xo. G 5 



