170 MILK 



placed on the left of the scale. The error at any point of the scale 

 shall not exceed 0.5 per cent. 



"2. Neck: (Same as standard milk test bottle.) The neck 

 shall be cylindric for at least 9 mm. below the lowest and above 

 the highest graduation mark. The top of the neck shall be flared 

 to a diameter of not less than 10 mm. 



"3. Bulb: (Same as standard milk test bottle.) The capacity 

 of the bulb up to the junction of the neck shall not be less than 45 

 c.c. The shape of the bulb may be either cylindric or conical, with 

 the smallest diameter at the bottom. If cylindric, the outside 

 diameter shall be between 34 and 36 mm.; if conical, the outside 

 diameter of the base shall be between 31 and 33 mm., and the max- 

 imum diameter between 35 and 39 mm. 



"4. The charge of the bottle shall be 9 grams. 



"5. The total height of the 6-inch bottle shall be between 150 

 and 165 mm. (5J and 6^ inches same as standard milk test bot- 

 tles); of 9-inch bottles, between 210 and 225 mm. (8} and 8J 

 inches) < 



"6. All bottles shall bear on top of the neck, above the gradu- 

 ations, in plainly legible characters, a mark defining the weight of 

 the charge to be used (9 grams). 



"Each bottle shall bear a permanent identification number. 



"Standard pipet: Total length of pipet not more than 330 

 mm. (13J inches). 



"Outside diameter of suction tube 6 to 8 mm. 



"Length of suction tube 130 mm. 



"Outside diameter of delivery tube 4.5 to 5.5 mm. 



"Length of delivery tube 100 to 120 mm. 



"Distance graduation mark above bulb 50 to 60 mm. 



"Nozzle straight. 



"Delivery 17.6 c.c. of water at 20 C. in five to eight seconds. 



"Standard of Accuracy for Babcock Glassware and Rules for 

 Testing. Section 1 : The unit of graduation for all Babcock glass- 

 ware shall be the true cubic centimeter (0.998877 gram of water at 

 4 C.). 



"(a) With bottles the capacity of each per cent, on the scale 

 shall be 0.2 c.c. 



"(6) With pipets and acid measure the delivery shall be the 

 intent of the graduation, and the graduation shall be read with the 

 bottom of the meniscus in line with the mark. 



"Section 2: The official method for testing bottles shall be 

 calibration with mercury (13.5471 grams of clean, dry mercury at 

 20 C. carefully weighed on analytic balances, to equal 0.5 per cent, 

 on the Babcock scale), the bottles being previously filled to zero 

 with mercury. 



