40 Testing Milk and Its Products. 



There is this objection to the latter method that, unless 

 carefully done, it is apt to weaken the bottles so that 

 they will easily break, and to both methods, that the 

 lead pencil marks made on such ground labels may be 

 effaced during the test if the bottles are not carefully 

 handled. Small strips of tin or copper with a number 

 stamped thereon are sometimes attached as a collar 

 around the necks of the bottles. They are, however, 

 easily lest, especially when the top of the bottle is 

 slightly broken, or at any rate, are soon corroded so 

 that the numbers can only be seen with difficulty. 



The best and most permanent label for test bottles is 

 made by scratching a number with a marking diamond 

 on the glass di- 

 rectly above the 

 scale on the neck 

 of the bottles or 

 by grinding a 

 number on the 

 bottle itself. In 

 ordering an out- 

 fit, or test bottles 

 alone, the oper- 

 ator may specify 



that the bottles FIG. 12. Waste-acid jar. 



are to be marked 1 to 24, or as many as are bought, 

 and the dealer may then put the numbers on with a 

 marking diamond. 



A careful record should be kept of the number of the 

 bottle into which each particular sample of milk is 

 measured. Mistakes often happen when the operator 



