146 ANALYSIS OF MILK. 



Volatile Acid Corrections. 



2. For each 60 parts of acetic acid add on 25 '5 parts. 



3. For each 88 parts of butyric acid add on 87-5 parts. 



4. For each 74 parts of propionic acid add on 68 '5 parts. 



AmiiwHia Correction. 



5. For each part of ammonia add on 5 "2 parts. 



Lactic Acid Correction. 



6. For each part of lactic acid subtract 0'05 part. 



Aldehyde Correction. 



1. For each degree of difierence between the aldehyde figure of 

 the neutralised solution obtained in the volatile acid estimation 

 and that of the solids not fat subtract 0-0026 per cent. 



Amino- Acid Correction. 



8. For each degree of aldehyde figure of the neutralised solu- 

 tion obtained in the volatile acid estimation above 20° subtract 

 0'0018 per cent. (This is rarely required.) 



Loss of Bulijric Acid. 



!'. Subtract the acidity of the solids not fat from the difierence 

 between the aldehyde figures of the volatile acid solution, and 

 of the solids not fat ; multiply the figure thus obtained by 0'0088, 

 and add it to the solids not fat. 



By this system of corrections the author and Miller have 

 found that the solids not fat deduced from the analysis of sour 

 milks has varied from 0"32 per cent, above the solids not fat 

 in the original milk to 0'20 per cent, below, and to average 0'06 

 per cent, above. The determinations on the original milks were 

 made by subtracting the fat by Gottlieb's method from the total 

 solids by evaporation. With milks in which no very large 

 amount of volatile acid was developed the figures were + 0'17, 

 — 0'19, and + 0'07 respectively. At the Government Labora- 

 tory only corrections Nos. 1, 2, and 5, and, if necessary, a correc- 

 tion of 92 parts for each 88 parts of butyric acid are made. The 

 author, however, believes that the additional corrections give 

 more exact results, though the difierence due to neglecting them 

 is small. The whole system of corrections is based on a long 

 investigation made at the Government Laboratory, which has 



