MILK AND MILK PRODUCTS 



23 



cm. long. The connection of this with the receiving flask is 

 made by means of a bulb tube to allow for occasional drawing- 

 back of the Hquid. The cork through which this tube passes 

 into the flask must not fit closely, as opportunity must be given 

 for expansion of the air. The safety tube connecting the 

 distilhng flask with the condenser should terminate a little 

 below the water level in the tank. The apparatus should be 

 heated by the low temperature burner or flat evaporating 

 burner. To avoid spurting of 

 the boiling liquid, it is usual to 

 interpose a safety-tube between 

 the distilling flask and the con- 

 denser. Many forms have been 

 suggested and are figured in the 

 catalogs of dealers in chemical 

 apparatus. The form shown in 

 figure 5 is somewhat compK- 

 cated but is satisfactory. The 

 distillation will be hastened if 

 this tube be covered with non- 

 conducting material. 



Ritthausen Method. — This 

 method depends on precipitation 

 by copper sulfate and sodium 

 hydroxid. It is apphcable only 



to fully developed milks; the proteids of colostrum and whey are 

 only partially precipitated. The reagents are given on page 27. 



10 grams of milk are placed in a beaker, diluted with 100 

 c.c. of distiUed water, 5 c.c. of copper sulfate solution added, 

 and thoroughly mixed. The sodium hydroxid solution is then 

 added drop by drop, with constant stirring, until the precipitate 

 settles quickly and the Hquid is neutral, or at most very feebly 

 acid. An excess of alkali will prevent the precipitation of some 

 of the proteids. 



Fig. S- 



