1908.] PUBLIC DOCUMENT — No. 33. 119 



tion with mercury is not permissible, as it involves many points 

 of uncertain value, and all tests 1 based on capacity should be 

 excluded. 



Section 4. The official method for testing pipettes and acid measures 

 shall be calibration by measuring in a burette the quantity of water (at 20° 

 C.) delivered. 



Limit of Error. 

 The demand of State officials as to accuracy and the claims 

 of manufactures as to their ability to graduate within definite 

 limits agreed very closely, consequently there was little diffi- 

 culty in presenting figures acceptable to both parties. 



Section 5. The limit of error. 



(a) For Babcock bottles, it shall be the smallest graduation on the 

 scale, but in no case shall it exceed five tenths (0.5) per cent., or for skim 

 milk bottles one hundredth (0.01) per cent. 



(b) For full quantity pipettes, it shall not exceed one tenth (0.1) cubic 

 centimeter, and for fractional pipettes five hundredths (0.05) cubic centi- 

 meter. 



(c) For acid measures, it shall not exceed two tenths (0.2) cubic cen- 

 timeter. 



The new standard was submitted to Dr. Babcock, and passed 

 without criticism. It w r as also sent to Professor Woll, referee 

 on dairy products for the association of official agricultural 

 chemists, to be presented at the 1907 meeting, but by some 

 oversight was not forwarded to the secretary. It will be 

 offered at the next annual meeting. 



It is desired to acknowledge the valuable assistance of the 

 manufacturers, Director Stratton and station officials, for with- 

 out their co-operation the proposed standard would not have 

 been deduced. 



i Connecticut Agricultural Experiment Station, twenty-fifth (1901) annual report, p. 

 281; Wisconsin Agricultural Experiment Station, ninth (1892) annual report, pp. 222, 223, 

 tenth (1893) annual report, p. 126; Testing Milk and its Products, fifteenth edition, Far- 

 rington & Woll, pp. 53, 54; Modern Methods of Testing Milk and Milk Products, L. L. Van 

 Slyke, p. 49. 



