to these authors contains no appreciable quantities of the 
water soluble vitamin furnished the carbohydrate of the 
diet *°. 
Source of Vitamin B, Treatment and Manner in Which it 
Was Fed. Dried skimmed milk was used as a convenient source 
of vitamin B. It permits the study of the effect of heat on the 
vitamin both in the wet and dry state. By using skimmed 
milk powder from the same lot throughout one experiment, 
possible variation in vitamin content is eliminated. 
The dry milk was heated at 100° C. for six, twenty-four 
and forty-eight hours in a constant temperature oven. It was 
spread out in thin layers about one-half inch in thickness and 
the temperature taken by means of a thermometer extending 
into the dry milk. Two hours were allowed, which was the 
time found to be necessary for the milk to come to 100° C. 
The portions heated six, twenty-four and forty-eight hours 
respectively actually remained in the oven eight, twenty-six 
and fifty hours. 
The reconstructed milk was prepared by weighing out 
100 grams of the air-dry powder and making it up to 1,000 cc. 
with water. For the heat treatment 250 cc. of this was poured 
into an Erlenmeyer flask and tightly stoppered with cotton. 
This was heated in a vigorously boiling water bath for six 
hours. A thermometer extending into the milk actually re- 
corded a temperature of 99.5° C. to 99.8° C. At the end of 
six hours the flask was removed from the bath and rapidly 
cooled under the tap. Since the volume diminished, due to 
evaporation through the stopper, the milk was again made up 
to volume before using. 
The milk was fed in doses of 8 cc. per rat per day for 
seven days a week, this, as will later be shown, being the 
amount which would best reveal any variation in vitamin con- 
tent. The milk was measured into a small cup by means of a 
graduated pipette and placed into the cage each day. If the 
rat did not drink the milk readily, the water cup was removed 
for the day and replaced in the evening. Usually this treat- 
ment brought the desired results. After two to three days all 
the rats took all the milk that was given them. The milk 
9 
