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. 



71. Method of Obtaming 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. 



73. 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 (&), 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. 



78. 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. 



