APPENDIX 315 
CHEMICAL STANDARDS AND METHODS 
The methods that must be followed in carrying out the chem- 
ical investigations essential to the protection of certified milk 
are so complicated that in order to keep the fees of the chemist 
at a reasonable figure there must be eliminated from the exam- 
ination those procedures which, whilst they might be helpful and 
interesting, are in no sense necessary. 
For this reason the determination of the water, the total 
solids, and the milk sugar is not required as a part of the routine 
examination. 
70. The chemical analyses shall be made by a competent 
chemist designated by the medical milk commission. 
V1. Method of Obtaining Samples——The samples to be ex- 
amined by the chemist shall have been examined previously by 
the bacteriologist designated by the medical milk commission 
as to temperature, odor, taste, and bacterial content. 
72. Fat Standards——The fat standard for certified milk 
shall be 4 per cent., with a permissible range of variation of 
from 3.5 to 4.5 per cent. 
78. The fat standard for certified cream shall be not less 
than 18 per cent. 
74, If it is desired to sell higher fat-percentage milks or 
creams as certified milks or creams, the range of variation for 
such milks'shall be 0.5 per cent. on either side of the advertised 
percentage and the range of variations for such creams shall be 
2 ‘per cent. on either side of the advertised percentage. 
75. The fat content of certified milks and creams shall be 
determined at least once each month. 
76. The methods recommended for this purpose are the 
Babcock (a), the Leffmann-Beam (b), and the Gerber (c). 
(See pages 233 to 239.) 
77. Before condemning samples of milk which have fallen 
outside the limits allowed, the chemist shall have determined, by 
control ether extractions, that his apparatus and his technic 
are reliable. 
%8. Protein Standard.—The protein standard for certified 
milk shall be 3.50 per cent., with a permissible range of varia- 
tion of from 3 to 4 per cent. 
