Frost—Bacteriological Control of Public Milk Supplies. 1327 
formed, rises through the oil and collects at C. It is possible of 
course, to obtain and maintain absolute anaerobic conditions in 
the medium situated as it is under oil. 
Fig. 10. New form of fermentation tube. 
HI. DETAILED ANALYSES OF VARIOUS GRADES OF 
MILK STUDIED. 
A. Classification of Milks. 
1. Schemes Proposed. The Commission on Milk Standards 
appointed by the New York Milk Committee! suggested that 
milks should be classified into the following grades:— 
Class A Certified milk or its equivalent 
Class B Inspected milk 
Class C Pasteurized milk 
Class D Milk not suitable for drinking purposes. 
This is practically the same classification suggested by Melvin.* * 
The Department of Health of New York City! has adopted a 
classification somewhat more elaborate. 
t Public Health Reports, 1912, 27, p. 673. 
* Milk and Its Relation to the Public Health. Hyg. Lab. Bull. 56, 
1909, p. 607. 
t Milk Supply of New York City, 1912. Dep’t of Health Monograph 
Series, 5, p. 13. 
