specific gravity than the butter fat, floats on top of the fat column 

 and eliminates the meniscus, the upper part of the fat column ap- 

 pearing as a straight line. 



The reading should be made immediately, before the fat begins to 

 contract and settle, at a temperature of 120° to 140° Fahr., and the 

 reading is equivalent to percentage when the normal amount of 

 material (18 grams) is taken. Too rapid cooling of the samples 

 may be checked by setting the bottle into a vessel of water heated 

 to 130° Fahr. 



The column of fat should be a clear yellowish liquid with a sharply 

 defined upper and lower meniscus or crescent, with no white curd or 

 charred material in or below the fat and no bubbles or foam on its 

 surface. Discoloration of the fat and charring is due to excessive 

 acid action, which may be caused by too strong, too much or too 

 warm acid, too warm a sample or failure to mix at once, or the 

 action of some preservative, especially bichromate of potash. 



Light colored fat and the presence of undissolved curd may be 

 caused by too weak, too little or too cold acid, too cold a sample, 

 insufficient whirling or lack of proper heat, or the action of some 

 preservative, especially formalin. 



Bubbles or foam on the surface of the fat may be due to the use 

 of hard water containing carbonates, or sometimes to excessive heat 

 in poorly constructed turbines, » 



The contents of the test bottles should be 

 Care of Glassware, shaken out while hot to remove the deposit of 

 lime sulfate, rinsed with clean water to remove 

 the acid, which interferes with the cleaning action of the soap, "N 



cleaned with hot soap suds, preferably made by using some strongly * 



alkaline soap powder, rinsed with hot water and allowed to drain. 

 Pipettes should be cleaned in a similar manner. The scale when 

 indistinct can easily be restored by rubbing over with an oil ship- 

 ping crayon. 



