APPENDIX 317 
deducted from the nitrogen obtained as described. (Farrington 
and Woll, Testing Milk and Its Products, p. 221.) 
82. Coloring Matter and Preservatives.—All certified milks 
and creams shall be free from adulteration, and coloring matter 
and preservatives shall not be added thereto. 
83. Tests for the detection of added coloring matter shall be 
applied whenever the color of the milk or cream is such as to 
arouse suspicion. 
Test for Coloring Matter.—The presence of foreign color- 
ing matter in milk is easily shown by shaking 10 c.c. of the milk 
with an equal quantity of ether; on standing, a clear ether solu- 
tion will rise to the surface; if artificial coloring matter has been 
added to the milk, the solution will be yellow colored, the inten- 
sity of the color indicating the quantity added; natural fresh 
milk will give a colorless ether solution. (Testing Milk and Its 
Products, Farrington and Woll, p. 244.) 
84. Tests for the detection of formaldehyde, borax, and 
boracic acid shall be applied at least once each month. Occa- 
sionally application of tests for the detection of salicylic acid, 
benzoic acid, and the benzoates are also recommended. (See 
pages 257 to 260.) 
85. Detection of Heated Milk.—Certified milk or cream 
shall not be subjected to heat unless specially directed by the 
commission to meet emergencies. 
86. Tests to determine whether such milks and creams have 
been subjected to heat shall be applied at least once each month. 
(See page 298.) 
87. Specific Gravity—The specific gravity of certified milk 
shall range from 1.029 to 1.034. 
88. The specific gravity shall be determined at least each 
month. (See page 228.) 
METHODS AND REGULATIONS FOR THE MEDICAL EXAMINA- 
TION OF EMPLOYEES, THEIR HEALTH AND 
PERSONAL HYGIENE 
89. A medical officer known as the attending dairy physi- 
cian shall be elected by the commission, who should reside near 
the dairy producing certified milk. He shall be a physician 
in good standing and authorized by law to practice medicine ; 
