26 Literatlire on Inosite-Phosphoric Acid [Sept. 



phide through the liquid ; the third is removed by adding dilute sul- 

 phuric acid. In all cases, the lead or copper salt is the last pre- 

 cipitated in this manner of purification; and when the product is 

 carefully washed, and the metal removed by hydrogen sulphide, the 

 filtrate from the lead or copper sulphide is evaporated at a low tem- 

 perature, leaving the inosite-phosphoric acid.^ 



The various salts which have been studied were made from this 

 acid. In obtaining the acid for the preparation of pure Compounds, 

 the greatest difficulty lies in removing the last traces of magnesium. 

 Rising overcame this difficulty by taking up the syrupy acid with 

 absolute alcohol, and adding ether until droplets of the acid formed. 

 He then filtered off the acid magnesium inosite-phosphate and again 

 evaporated. The commonest impurity in phytin is inorganic ortho- 

 phosphate which, however, is easily removed. Starkenstein uses the 

 calcium salts of the mixed acids and washes with glacial acetic acid, 

 which dissolves the inorganic part but not the organic phosphorus 

 Compound. Forbes precipitates with magnesia mixture, removes 

 the excess of this reagent by washing with ammonia water, washing 

 again with alcohol, and extracting with 95 per cent. alcohol con- 

 taining 0.2 per cent. mineral acid, which also dissolves all the in- 

 organic phosphorus and none of the " phytin." Attempts to prepare 

 these salts synthetically will be referred to in a later section. 



PROPERTIES OF INOSITE-PHOSPHORIC ACID AND ITS SALTS 



The substance widely known as "phytin," and described in the 

 middle of the last Century by the microscopists as " spheroid bodies," 

 frequently assumes the globular shape when forced out of Solution, 

 In most cases, the precipitate comes down as a flocculent amorphous 

 mass. Inosite-phosphoric acid has not as yet been obtained in crys- 

 talline form. At room temperature, it is a syrup of light straw 

 color, which becomes very viscid on cooling to — 20° C, and darkens 

 on heating to 100° C. Vorbrodt found that this coloration could 

 not be prevented by replacing the air with an inert gas during the 

 heating, and from this concludes that the change is not due to 

 oxidation. If the heat is allowed to reach 125° C, an insoluble dark 

 char is produced (cf. Posternak). Inosite-phosphoric acid may 



'For details of the method of preparing the acid see Hart and Patten 

 (page48). 



