AMERICAN ASS(X;i A'lIOX TESI 105 



form and correspond closely to chemical anal_\"sis (The Rose- 

 Gottlieb test), as the accompanying table shows. 



(2) There is much less trouble with a deposit in the test 

 bottles than is the case where the other alcohols are used. 



(3) Xormal butyl (»-but}-l) alcohol, being a single alcohol 

 that is readily jjuritied, is free of impurities while the am_\'l and 

 iso-but}'l alcohols are not likeh" to be. In blank tests made, 

 that is, when water was substituted for buttermilk in a test, a 

 short column ol' some impurity rose into the neck of the test 

 bottle when the amyl and isodjutyl alcohols were used, but not 

 when « -butyl alcohol was used. 



(4) The H-butyl alcohol is quite stable and is not at all likely 

 to be attacked by the sulphuric acid, while the other alcohols 

 mentioned are iso-alcohols that run off into chains and are less 

 stable and are likely to be mixtures. 



(5) The «-butyl alcohol does not possess either a pungent or 

 an otherwise offensive flavor or odor, and consequently is much 

 pleasanter to use than the others. 



(6) The H-butyl alcohol is the lowest in price of the dif- 

 ferent alcohols, and, being stable and free of impurities, is the 

 most reliable alcohol t<.) use. Even the cheaper grade of this 

 alcohol (the " practical ") ccmtains no impurity excepting pos- 

 sibly a slight amount of moisture. 



Extensive and carefuU}- conducterl in\-estigations have 

 shown that the right amounts of commercial sulphuric acid 

 and «-butyl alcohol to use in testing a g-grani sample of 

 skim-milk or butter-milk are as given in the directions which 

 follow : 



Directions f(jr making a test: 



Chemicals. — Commercial sulphuric acid. 

 Normal butyl alcohol. 



I. Place the chemicals and buttermilk in the test bottle in 

 the foUowing amounts and the order indicated. 



(of) 2 c.c. of »-butyl alcohol. 



{b} 9 c.c. of buttermilk. 



(c) 7 to 9 c.c. of commercial sulphuric acid. 



Vary amount of acid to suit its strength. The right amount 



