830 EXPERIMENT STATION RECORD. 



80 per cent acetic acid to the milk after measuring- out in the test 

 bottles and heating to boiling, or in a water bath with air conducted 

 into the bottles to prevent frothing. The boiling is continued until the 

 liquid in the test bottle does not exceed the volume of milk taken, ?. c, 

 17.6 cc. The solvent action of the acetic acid on the casein at the boil- 

 ing temperature is said to considerably reduce the amount of sulphuric 

 acid necessary, so that from 13 to 15 cc. of sulphuric acid of the usual 

 commercial strength is said to be sufficient. The test is then made in 

 the ordinary way. 



"A uotable difference is seen iu the qiiality of the results when the readings are 

 taken. The fat now appears clearer, more transparent, and more sharply defined at 

 the top and at the bottom than iu the average test in the ordinary way. The defi- 

 nition, that is, the clearness of the top line and the dividing line between the fat 

 and water, is, almost without exception, perfect. The fringe of undissolved curd at 

 the bottom of the fat, not infrequent in the ordinary method, especially in unskillful 

 hands, is almost never seen. The fat column is so clear that it would be apparent 

 at sight whether it were pure fat or part curd. . . . 



"While the process here described is more complicated than the ordinary test, it 

 seems to be more certain and accurate, at least in unskillful hands. With a dozen 

 samples to test it would require somewhat more time, but with 50 or 100 it would 

 require very little more, as the several operations would overlap." 



The results must be corrected for the carbon bisulphid added, and 

 to facilitate this a table is given. 



The results are given of a number of trials of this method of pre- 

 serving the sample in comparison with gravimetric analyses. "In the 

 practical trial of the method the results are excellent." 



For measuring out the carbon bisulphid it is suggested to use a 

 pipette connected with a bulb and having a small vent hole in one side. 

 A shaking apparatus for shaking the test bottles after adding the sul- 

 phuric acid is illustrated and described. 



The use of borax preservatives on cream-gathering routes, 

 W. Freak and W. S. Sweetser {FennsyJvania 8ta. Rpt. 1895, i)p. 

 86-89). — An experiment was made in which 4 teaspoonfuls of a mixture 

 of equal parts by weight of fine dairy salt and powdered borax was 

 mixed with nearly 3 gal. of cream, the cream subsequently churned in 

 a small test churn, and the butter worked, salted, etc., as usual. Sam- 

 ples of the butter were repeatedly washed by agitation in hot water in 

 a separatory funnel and the washings tested for borax by a delicate 

 method, but none was found. A repetition of the trial gave the same 

 result. 



"These tests are conclusive evidence that the borax i^reservatives, 

 even when used iu much greater proportion than is customary on cream- 

 gathering routes, are carried over into the butter, if at all, in quantities 

 too small to produce any effect upon the consumer." 



To the objection that the bacteria of the starter would be retarded 

 by the preservative just as the injurious bacteria are, the author sub- 

 mits that "this difficulty is not a great one practically, as a slight 

 increase in the amount of the starter or in the time of action will 

 suffice to overcome the retarding influence of the borax." 



