ADDENDA. 



479 



p. 307, G. C. Jones finds the average composition of milk for the years 

 1909-1918 : 



P. 355. 



Total mean fat, 3-76 ; solids not fat, 8-89. 



He has found that the shortened hours of agricultural labour 

 have resulted in a departure from the usual milking intervals, 

 with a marked effect on the relative compositions of the 

 morning and evening milks. Thus, in February, 1920, the 

 morning samples averaged 3-32 per cent, of fat, or 0-22 below 

 the average, and the evening samples 4-06 per cent., or 0-22 

 above, the average composition of the daily supply being 

 unaffected. A tendency for poorer morning milk, and richer 

 evening milk, due to economic causes, is anticipated, and 

 it is to be expected that the number of genuine cases of 

 morning milk falling below 3-0 per cent, may increase. 



P. 362. For the detection of abnormal milk Baker and Van Slyke add 

 one drop of a saturated solution of bromo-cresol purple (di- 

 brom-o-cresol-sulphon-phthalein) to 3 c.c. of milk. Normal 

 fresh milk gives a greyish-blue colour, and lighter colours 

 may be due to acidity, formaldehyde, or heating to a high 

 temperature. A deeper blue is given by milk from diseased 

 udders, watered or skimmed milk, and by the presence of 

 alkaline salts. Stages in the production of acidity on keeping 

 may be followed by progressive changes of colour at intervals. 



P. 365. The table (p. 480), based on that of Thorpe, shows the inter- 

 dependence of the criteria in the analysis of butter fat. 



P. 392. Silva finds that at 65 the rate of destruction of the peroxydase 

 by heat is so slow as to be negligible, but from 69 to 71 

 the rate of destruction increases 2 '23 times for each degree, 

 and at 72 it is too fast to be measurable. Acids and salts 

 retard and alkalies increase the rate of inactivation. Lane- 

 Claypon has shown that the peroxydase is not removed with 

 the casein nor with the cream, but appears to be precipitated 

 with the albumin. 



