'Testing the Purity of Milk. 



133 



as well as such as is to be retailed or used in the manu- 

 facture of high-grade butter and cheese. 



In distinguishing milk fit for pasteurization purposes 

 from that which is doubtful, an arbitrary standard of 

 two-tentlis of one per cent, of acid may be taken as tha 



;unce 



Botlle. 'Measure 



Kiu, jr 



.Apparatus used for rapid estimation of the acidity of ap- 

 pareutly sweet milk or cream. 



upper limit for milk of the former kind. The appara- 

 tus used in making this test is shown in the accompany- 

 ing illustration (fig. 45), and consists of a white tea- 

 cup ; a four-, six-, or eight-ounce bottle, and a No. 10 

 brass cartridge shell, or a similar measure. A solution 

 of the tablets in water is first prepared, one tablet being 

 always added to each ounce of water: four tablets in a 

 four-ounce bottle; six, in a six-ounce bottle, etc., the 

 amount of tablet solution prepared depending on the 



