761 



On the composition of milk and milk products, P. Vieth {Analyst, April, 

 1891, pp. 01-67). — 111 a paper read before the Society of Public Analysts, 

 Dr. Vieth presented a report of the work done in tiie laboratory under 

 liis charge duriug the year 1890. This work includes the analysis of 

 20,(>.'}5 samples of milk, 1,188 of cream, 580 of skim-milk, 105 of butter 

 and butter fat, besides numerous samples of buttermilk, whey, water, 

 and sundry other articles. 



Of the milk, 11,810 samples were taken on arrival from the country, 

 and in order to keep a constant control over the men intrusted with its 

 delivery to customers, 7,104 samples were taken before, during, and 

 after deliv^ery. The average of these analyses for the year is given as 

 follows : 



Average composition of milk and cream, 1890. 



"The lowest percentage of total solids and fats was found, as usual, 

 in the second, and the highest in the fourth quarter of the year. * * * 

 Skim-milk, resulting when cream was separated from milk by means of 

 centrifugal cream separators, contained, as a rule, from 0.2 to 0.4 per 

 cent of fat." 



The volatile acids found in ditferent butters in 1890 were, in " Wollny 

 figures," as follows : 



English butter, 25.3-30.0; average 27.6 c. c. 

 French butter, 2.5.6-30.8; average 28.7 c. c. 

 Kiel butter, 21.3-30.7; average 27.7 c. c. 

 Danish butter, 27.3-29.9; average 28.8 c. c. 



The author mentions four cases in which the volatile acids of Kiel 

 butter " derived from two large, well-known, and well-managed dairies in 

 Holstein" were, respectively, 24.2, 22, 21.3. and 23.7, or below the usual 

 limit. These same dairies furnished butter low in volatile acids in 1889. 

 A study of this matter at the dairy experiment station at Kiel showed 

 that " with the progress of the period of lactation the volatile acids 

 decreased, reaching their lowest point in October, and that with the 

 beginning of the calving season, in November, they at once increased 

 and quickly rose above 25." Butter from an English farm, of which 32 

 samples were examined during the year, " fell below 25 from January to 

 the middle of April and again from August to November. During the 

 remaining part of the year the volatile acids varied from 25 to 26. The 

 observed extremes were 22.1 and 20.2." 



The volatile acids of butter fat which had been exposed to the action 

 of air and light for 18 months and had become bleached, increased from 

 29.2 in the original to 30.4 in the bleached sample. 



