Testing the Acidity of Milk and Cream. 127 



a 50 ec. cylinderful of tablet solution of this strength 

 will not be sufficient to make a test of cream containing 

 over .5 per cent, of acid, although it is enough for test- 

 ing the cream up to this point during the ripening pro- 

 cess. The acid-testing outfit should therefore contain a 

 100 cc. graduated cylinder, instead of one of 50 cc. capa- 

 city, so that cream of any amount of acidity up to 1 

 per cent, can be tested. A tablet solution of the strength 

 given has not only the advantage over the solution pre- 

 viously recommended (5 tablets to 50 cc. of water)' 

 of showing the per cent, of acidity directly, without 

 tables or calculations, but being weaker, the unavoid- 

 able errors of determination are decreased by its use. 



Since a 17.6 cc. pipette is found in creameries and 

 dairies with the Babcock test outfit, no new apparatus is 

 necessary for making the acidity test in the manner 

 given. 



140. The preparation of the standard solution is as 

 follows: Five tablets are placed in the 100 cc. cylinder 

 which is filled to the 97 cc. mark with clean soft water.^ 

 The cylinder is tightly corked, shaken and laid on its 

 side, as the tablets dissolve more quickly when the cyl- 

 inder is placed in this position than when left upright 

 with the tablets at the bottom. Several cylinders con- 

 taining the tablet solution may be prepared at a time; 

 as soon as one is emptied, tablets and water are again 

 added, and the cylinder is corked and placed in a hori- 



' Illinois experiment station, bulletin 32; Wisconsin experiment sta- 

 tion, bulletin 52. 



' Condensed steam or rain water should be used, and not hard or 

 alkali water, since tbe impurities in these affect the strength of the 

 tablet solution. 



