14 Dirercror’s REPORT OF THE 
ct.; the water-soluble arsenious oxide, from 0.88 to 2.64 per ct., 
with an average of 1.28 per ct.; the copper oxide, from 26.53 to 
31.14.per ct., with an average of 29.88 per ct., and the arsenious 
oxide in combination with copper, from 49.70. to 57.72 per ct., 
with an average of 55.98 per ct. These results indicate that the 
Paris green in the market during 1901 was of good quality in 
every respect. 
Inspection of Babcock glassware—tIn 1901 the Station tested 
glassware for seventy-seven cheese factories and creameries, 
including 3,473 milk test bottles, 56 cream bottles and 97 
pipettes. Of these 119 were found incorrect and rejected. 
The Station is not required to inspect cheese factories and 
creameries to determine whether they are complying with the 
law as to Babcock glassware. The responsibility in respect to 
this compliance rests entirely with those having the manage- 
ment of the factories and creameries. 
ANIMAL HUSBANDRY. 
¢ 
The food source of milk fat—The results reported in Bulletin 
No. 197, relating to the food source of milk fats, were in con- 
tinuation of the investigations discussed in Bulletin No. 132. 
The conclusion reached in the former experiment that part, 
at least, of the milk fat comes from the carbohydrates is con- 
firmed; and other facts relating to metabolism and the utiliza- 
tion of food by milch cows are brought out. 
Three cows were used: Cow 12 fed a fat-poor ration in which 
the protein supply was gradually decreased from 2.6 lbs. daily to 
1.6 lbs. and then gradually restored to the maximum, with 
accompanying increase and decrease in carbohydrates so that the 
digestible dry matter of the ration was kept fairly uniform; 
Cow 10 fed a ration with normal supply of fat at first which was 
gradually increased to 1.4 lbs. daily, then gradually restored to 
the normal; Cow 2 fed the herd ration having a nutritive ratio 
about 1:5.6. These rations were quite varied in character and 
contained some fat-extracted foods; yet they showed a quite uni- 
form digestibility of about 70 per ct. of the dry matter. It is 
