234 



THE CHEMICAL CONTROL OF THE DAIRY. 



7. 10 c.c. bulb pipette for acid. The bulbs prevent the acid 

 from being drawn into the mouth. 



8. Automatic measuring apparatus, or burettes, as an alter- 

 native means of measurement. 



Chemicals. — Commercial sulphuric acid, specific gravity of 

 1-820 to 1-&25 at 15° C. (59° F.) (contains 90 to 91 per cent. 

 H2SO4). The specific gravity may be taken with a hydrometer. 



Fig. 29.— Amyl Alcohol 

 Measure for Gerber Test. 



Fig. 30. — Acid Measure for Gerber 

 Test. 



Should the temperature not be exactly 15° C. (59° F.) the specific? 

 gravity may be corrected by adding on 0-001 for each degree 

 Centigrade (or 0-00056 for each degree Fahrenheit above 59°) 

 above 15°, and by subtracting 0-001 for each degree below 15° ; 

 thus, if the temperature be 20° and the specific gravity 1-818, 

 the corrected specific gravity will be 1-818 + 5 x 0-001 = 1-823;. 



