from wheat bran we (Anderson 1912 (3) ) obtained evidence of the 

 presence of pentose and Rather (1913) also showed that such prepara- 

 tions contain varying amounts of pentose. Small quantities of these 

 soluble carbohydrates adhere to the inosite phosphoric acid prepara- 

 tions with great tenacity. We have noticed that barium salts of 

 inosite phosphoric acid isolated from various plant material gener- 

 ally show too high a percentage of carbon in the early stages of puri- 

 fication. 



In order to obtain salts having constant composition it is neces- 

 sary to recrystallize them a great number of times. We have found 

 that it is possible to obtain preparations having uniform composition 

 after repeated, careful recrystallization of the products. After this 

 degree of purity has been attained further crystallization does not alter 

 the composition. All of the crystalline barium salts which we have 

 thus obtained correspond in composition to salts of inosite hexaphos- 

 phoric acid; i. e., the relation of C : P is as 6 : 6. We believe for this 

 reason that the inosite phosphoric acid exists in plants or in the 

 majority of plant material at least as salts of inosite hexaphosphoric 

 acid. In this connection it should be noted that it is very much easier 

 to obtain preparations from plant extracts which differ in composition 

 from those just mentioned. In order to obtain preparations corre- 

 sponding in composition to salts of inosite hexaphosphoric acid the very 

 greatest care is necessary in the manipulations connected with the isolation 

 and purification. In isolating the material from wheat bran, for instance, 

 the bran must not be digested in 0.2 per cent, hydrochloric acid, but in 

 an acid solution of such strength as to inhibit the activity of the 

 enzyme phytase. The same applies when isolating the preparation 

 from rice bran. Unfortunately, several investigators appear to have 

 overlooked this important fact. It might be argued that repeated re- 

 crystallizations might cause decomposition or pa'rtial hydrolysis of 

 the product, for these purifications naturally require considerable time. 

 Of course, that danger always exists. We have always employed as 

 mild methods as possible, avoiding contact with strong acid and care- 

 fully avoiding heat. The various operations have been performed as 

 rapidly as possible. But even when working with the greatest pos- 

 sible rapidity it is sometimes not possible to complete the isolation 

 and crystallization of a particular preparation in less time than a week 

 or ten days. If a notable amount of hydrolysis occurred during this 

 time when the substances during crystallizations are in contact with 

 dilute acid for varying periods, the resulting product should show a 

 steady increase in carbon content and a decrease in the percentage of 

 phosphorus because the hydrolysis is progressive, the molecules of 

 phosphoric acid splitting off one by one. This is not the case, how- 

 ever, for, as mentioned above, such carefully recrystallized barium 



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