AGRICULTURAL CHEMISTRY — AGROTECHNY. 113 



the basis of the consistency of the coagulum obtained with the alcohol test 

 alone Is deemed imcertain. A method foi* proving the value of the alizarol test 

 is included in the article. 



Titration of milk with alcohol of various concentrations, F. Lohnis {Molk. 

 Ztg. [Hildesheim], 28 (1914), No. 9, pp. 153-155).— The alcohol test has been 

 modified as follows: 



Two cc. of the milk under examination is placed in a beaker and titrated with 

 80 per cent alcohol until the appearance of coagulation, the number of cubic 

 centimeters of alcohol required indicating the alcohol number of the milk. The 

 coagulating point of milks which require more than 6 cc. of alcohol is hard to 

 determine. The test is said to be an index to the number of bacteria present 

 in the milk, a milk with a low germ content requiring more than 4 cc. of alcohol, 

 while that of a medium micro-organism content requires from 2 to 4 cc, and 

 high germ contents less than 2 cc. 



The alcohol test in relation to milk, S. H, Ayeks and W. T. Johnson, Jk. 

 (U. 8. Dept. Agr. Bui. 202 {1915), pp. S5, figs. 4).— The purpose of this work 

 was to determine the practical value of the alcohol test for the quality of 

 milk, and incidentally to determine some of the causes for the coagulation of 

 milk by alcohol. 



Fresh milk from a single healthy cow in the middle of the period of lacta- 

 tion was found to give occasionally a positive alcohol test with an equal 

 volume of 68 or 70 per cent alcohol. Colostrum gives a positive reaction, and 

 the same is true, usually, of "old" milk (milk from a cow in the last of its 

 lactation period). Normal milk when mixed with colostrum milk did not show 

 positive with the 68 per cent alcohol test until the amount of colostrum milk 

 reached 80 to 90 per cent. " When 75 per cent alcohol was used the test was 

 positive with as low as 25 per cent of colostrum milk, but when colostrum milk 

 from another cow was used a mixture of 80 per cent was required to give a 

 positive reaction Avitli 75 per cent alcohol. It seems evident from these results 

 that the mixing of colostrum and normal milk would not cause a positive alcohol 

 test unless a very large percentage of the milk were colostrum milk." 



As a result of reviewing the literature on the behavior of the alcohol test 

 with market milk, it was evident that the acidity inlays a part in the alcohol 

 test. In the present investigation it was found that if the acidity was raised 

 by the addition of 1 cc. of deciuormal lactic-acid solution, a medium-sized flake 

 coagulum with 75 and 68 per cent alcohol could be obtained. " Since an in- 

 crease in acidity will cause a positive alcohol test, it is evident that the growth 

 of acid-forming bacteria in milk will cause a positive test. 



"In order to determine the relation between the number of acid-forming 

 bacteria, the acidity, and the alcohol test, two experiments were performed, 

 using a pure culture of a lactic-acid-producing organism." In one of the sam- 

 ples of milk the alcohol test was negative 7 hours after incubation, but in the 

 second sample, where a larger portion of bacterial culture was used for the 

 inoculation (at the beginning of the incubation 480,000 bacteria were present), 

 the alcohol test with 75 per cent alcohol was positive on the fifth day, when 

 the number of bacteria reached over 16,000,000. On the sixth day 68 per cent 

 alcohol gave a positive test and the number of bacteria was 31,400,000. 



Since the acidity of milk is due partly to phosphates, the effect of sodium 

 and potassium acid phosphates on the outcome of the alcohol test was studied. 

 " The results show that it is possible by increasing the acidity of milk with 

 acid phosphates to cause a coagulation with the alcohol test, but the acidity 

 has to be increased to a high degree, and there would never be enough acid 

 phosphate in a mixed market milk for it to be entirely responsible for a posi- 

 tive alcohol test. . . . When from 7 to 8 cc. of decinormal lactic acid was 



