THE USE OF THE BABCOCK TEST.

New Zealand Mail, Issue 1191, 28 December 1894, Page 4

THE USE OF THE BABCOCK TEST.

Bulletin No. 27, of Illinois Agricultural Experiment Station, by Prof.

E. H. Farrington. (From the American Dairy Messenger.)

This bulletin contains some valuable pointers on the use of the Babcock test, and confirms what wrehave always claimed that while the test is exceedingly simple, yet it requires some training to use it right. Prof. F. has made at least 150 tests per day since May Ist, and it behoves everybody using the test tocarefully note the following conclusions, which may obviate the necessity of returning the acid because the test has either white or black substance. «' First— An acid having 1 82 sp. gr. should be used with milk at 60deg. to 70deg. F. If the acid is stronger, cool the milk at a lower temperature. Somewhat weaker acid c*n probably be made to work all right by warming the milk. " Second— When measuring the acid into the test bottles, hold the bottle at an angle that will cause the acid to follow the inside walls to the bottom of the bottle, and not drop through the milk in the centre of the bottle. If properly poured into the test bottle, chore will be a distinct layer of milk and acid, with little or no black colour between them. " %hird —Thoroughly mix the milk and acid as soon as measured into the test bottle. A better separation of fat is obtained by mixing at once than by allowing the two liquids to stand unmixed in the bottle until enough tests have been measured out to till the centrifuge. "Fourth— After five minutes' whirling of the test bottles in the centrifuge, add hot water until the test bottle is filled up to the neck only ; run the centrifuge one minute, then fill the neck of the test bottle with hob water, and run the centrifuge another minute. Adding the necessary hot water in two portions is often a great help in getting a clear separation of fat. When the test bottles are taken from the centrifuge, they are put into water at 140 deg. to 160ieg. F., and the per cent, of fat read at that temperature. "Fifth—Too low results will be obtained if the centrifuge does not have sufficient speed. The machines have to be watched, as constant use wears some of them, so that the speed designed by the manufacturer is not obtained. "Sixth— When testing skim-milks or butter-milks which have a very small per cent, of fat (two-tenths cf one per cent., or less), the reading of the percent, of fat should be made immediately on taking the test bottle from the centrifuge. If this is not done, and the test bottle cools before taking the reading, the contraction of the liquid in the bottle will often leave the fat spread over the inside surface of the measuring tube, so that it is not seen, but has the appearance of i being only a dirty tube. If read when

taken from the machine, the small globules of fatcati be seen and estimated.'' There is one conclusion in which we believe the Professor to be m'staken, and that is when he saya : "The action of the acid on the milk will be more or less intense, according to the temperature of the liquids. Persons who have tested milk throughout the year, at creameries or other places, may have noticed that in winter the fat is .often light coloured or whitish, while in summer it is a deep yellow. This variation in colour is caused by the difference in the temperature of the milk and acid, as well as the strength of the acid.'' At least, we have had a great variation from nearly whi'e to a strong yellow colour in the fat from different milk at the same temperature and with the same acid, and hence we belieVe the variation in Colour is more apt to be caused by the same rtason as it is in butter—natuely, feed, breed, individuality, and period of lactation.