aration of inorganic phosphoric acid. Concentrated solutions of the 

 acid undergo gradual spontaneous decomposition at room temperature, 

 but much more rapidly when heated. The decomposition is only par- 

 tial ; i. e., there is formed inorganic phosphoric acid but no inosite. 

 After standing for 18 months a sample of the acid contained con- 

 siderable free phosphoric acid but no inosite. Heating this same acid 

 for 48 hours to 100° caused some of the acid to decompose completely 

 because inosite was found as one of the products of decomposition, but 

 only to a small extent. Dilute solutions of the freshly prepared acid 

 give no precipitate with ammonium molybdate either in the cold or 

 on heating for half an hour- at 60°. Continued heating at 60°, however, 

 causes a gradual separation of a small amount of yellow precipitate 

 due to hydrolysis of the acid with formation of phosphoric acid. In 

 concentrated solutions ammonium molybdate produces a white 

 crystalline precipitate. The acid is soluble in all proportions in 

 alcohol, but insoluble in other organic solvents. The addition of 

 ether to an alcoholic solution of the acid causes a cloudiness and the 

 acid gradually separates out in minute oily drops. The acid coagu- 

 lates egg albumin immediately, even in dilute solutions. The alkali 

 salts are very soluble in water. Posternak states that the acid alkali 

 salts are also soluble in alcohol and water. Aqueous solutions of the 

 acid are not precipitated by the chlorides of the alkaline earths, but 

 the acetates and hydroxides of these metals give white amorphous pre- 

 cipitates. Magnesium acetate, however, precipitates the acid only 

 from neutral solutions. Alcohol produces in solutions containing the 

 acid and the above chlorides white amorphous precipitates, but the 

 salts of magnesium and calcium are less completely precipitated than 

 those of strontium and barium. While barium chloride and the acid 

 give no precipitate, yet on allowing such a solution to stand a few 

 hours, needle-shaped crystals of the barium salt separate. Silver nitrate 

 in excess produces a heavy, white, amorphous precipitate. Precipitates 

 are also produced with other heavy metals. Copper acetate in excess 

 produces green colored precipitates, even in the presence of dilute 

 acetic, hydrochloric of sulfuric acids. Lead acetate gives white pre- 

 cipitates in solutions of the free acid or in solutions of its salts in 

 acetic acid. The copper and lead salts of inosite phosphoric acid are 

 particularly suitable for isolating the acid because these metals can 

 be easily removed by hydrogen sulfide. All of the salts of inosite 

 hexaphosphoric acid except the iron salt are more or less easily soluble 

 in dilute mineral acids. The iron salt is very sparingly soluble, even 

 in strong hydrochloric acid. The great insolubility of this salt in 

 dilute acids has led to the development of a volumetric method by 

 Heubner and Stadler (1914) for determining inosite phosphoric acid 

 by titrating with a standardized solution of iron chloride, using arrimo- 



15 



