CRYOSCOPE TEST IS CHALLENGED.

Star (Christchurch), Issue 18585, 10 October 1928, Page 10

CRYOSCOPE TEST IS CHALLENGED.

THE DETERMINATION OF ADDED WATER IN MILK.

The infallibility of the cryoscopic, or freezing point test for determining the amount of added water in milk was attacked by the defence in a case before Mr H. P. Lawrv in the Magistrate’s Court this morning; Annie Henry (Mr Cavell) was charged with having sold milk containing added water. Mr Brown prosecuted. The defence, Mr Cavell stated, rested on the infallibility of the cryoscopic test. Counsel said that expert evidence had been secured and the test be attacked. Also, it would be proved that the milk which was tested was not drawn from a bulk intended for human consumption, as was specified in Section 22, Sub-Section 2, of the Act.

Mr Brown said that Mrs Henry’s cows were milked at unusual times, 2.30 a.m. and 10.30 a.m. and samples had been taken from both milkings. The cryoscopic test, which was accepted as infallible all over the world, had to do with the freezing point of milk as compared with that of water. The test had shown that there was 8.1 per cent of added water in the sample of milk. The lactometer showed that the percentage of solids in the milk was 8.5 per cent, the bare legal limit. When dried out, the percentage was 8.45 per cent. That was a very low percentage.

Thomas Edward Shaw, inspector, gave evidence of the sampling. There were a lot of empty cans, and the sample was taken from a can apart from them. Mrs Henry told him that there was no milk, as all the cans that had been taken on the round were empty, but when she found the other can which contained some milk she called witness back and sold him a sample. To Mr Cavell: Defendant did not tell me that the milk she sold me was not milk for sale to her customers. I told her what I was taking the sample for. Felix J. T. Greigg, Government Analyst, gave evidence of the testing of the samples. lie had used the cryoscopic, or freezing point test to determine the amount of added water. He had used that test for six years, and in the case under notice had applied it three times. The freezing point of normal milk had a very small range, from .545 to .565 degrees. The general sample froze at .550. The cryoscope was a specially graded thermometer. The lactometer provided a rough test for solids. It was accurate to within a margin of .1 per cent. The drying out test followed.

Cross-examined by Mr Cavell, witness said that there*vas no doubt about the reliability of the cryoscopic test, which had been proved infallible.