14 Director's Kei'ort of the 



ft.; the water-soluble arseiiious oxide, from 0.S8 to 2.04 per ct., 

 with an averaj^e 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 wuth copper, from 4J).70 to 57.72 per ct., 

 with an average of 55.98 per ct. These results indicate that the 

 I'aris green in the market during 1901 was of good quality in 

 every respect. 



Inspection of Bahcock glassware. — In 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 sovrcc of milk fat. — The results reported in Bulletin 

 No. 107, 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 sui)ply 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; 

 (\)w 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 uiu'mal; Cow 2 fed the herd ration having a nutritive ratio 

 about 1:5.6. These rations w^ere quite varied in character and 

 contained some fat-extracted foods; yet they shoAved a quite uni- 

 form digestibility of about 70 per ct. of (he dry matter. It is 



