196 THE VITAMINES 



demonstrated. This method is more certain, though it has the draw- 

 back that much more time is required for its application. Both of 

 these methods have the great disadvantage that in isolation experi- 

 ments, every new fraction must await the findings of the animal 

 experiments, the vitamine preparation in the meantime being subject 

 to more and more decomposition. For these reasons, efforts have 

 long been made to develop a method that would permit of conducting 

 a test in the shortest possible time. For practical reasons too, such 

 a method would be of advantage in determining the vitamine- content 

 of various foodstuffs. 



The first step in this direction was made by Fraser and Stanton 

 (I.e. 55) . Based upon Schaumann's theory of the lack of phosphorus, 

 they believed that the vitamine content of rice could be estimated 

 by the amount of phosphorus present. Voegtlin and Myers (516) 

 also suggested the phosphorus content of wheat and corn as a some- 

 what reliable indication of the amount of vitamine contained therein. 

 On the other hand, Green (517) showed that if the phosphorus 

 content of American corn is taken as a unit, then all South African 

 varieties of corn, which are very poor in phosphorus, might be 

 regarded also as very poor in vitamines, which is, however, not the 

 case. Ottow (518) is likewise of the opinion that the estimation of 

 the phosphorus content alone may lead to false conclusions. He 

 believed that the determination of the quantity of alcohol-soluble 

 fraction of rice was more reliable, at the same time regarding the use 

 of animal experiments as the only method to be relied upon. 



We (519) sought, at first, to form some conception as to the 

 amount of vitamine present, by determining the nitrogen in foodstuffs 

 having a slight non-protein nitrogen, such as milk. For this purpose, 

 we dried some milk, made an alcoholic extract of the portion precipit- 

 able by phosphotungstic acid, and analyzed it for its nitrogen content. 

 The only result apparent was that on centrifuging the milk, a 

 large part of the residual nitrogen is lost and evidently goes over 

 into the cream. Whereas in a non-centrifuged milk this fraction 

 amounts to about 2.2 mgm. per liter, in the centrifuged milk it is 

 only 1.4 mgm. This shows perhaps that milk fat (butter) may 

 contain nitrogenous vitamine. Furthermore, since we noted that 

 vitamine fractions contained substances whose nitrogen could be only 

 partially estimated by means of a Kjeldahl determination, we wanted 

 to make use of the difference between the analyses, according to 



