28 Literature on Inosite-PJwsphoric Acid [Sept. 



calcium and Strontium ; but the magnesium and alkali salts, and the 

 double salts, are very soluble in this reagent. Posternak says that 

 the alkali salts of this acid are solvents for the Compounds with 

 alkali earths, and that on standing, crystals of double salts form in 

 these Solutions, tending to arrange themselves in rosettes — a further 

 Suggestion as to the mode of formation of the characteristic sphero- 

 crystals mentioned above. Inosite-phosphoric acid Solutions do not 

 polarize light, and pass through semi-permeable membranes com- 

 paratively slowly. 



All the salts of inosite-phosphoric acid, except the alkali salts and 

 the acid magnesium salts, are precipitated f rom aqueous Solution by 

 four volumes of alcohol. The acid and its salts in alcoholic Solu- 

 tion are precipitated by ether. The addition of neutral Solutions of 

 silver, lead, copper, cadmium, iron, uranium, Strontium, barium and 

 calcium precipitates the acid f rom its Solutions ; so also do magnesia 

 mixture and albumin. According to Posternak, precipitation with 

 copper is prevented by the presence of fat. The copper salts are 

 soluble in ammonium hydroxid Solution. Ammonium molybdate in 

 nitric acid does not cause precipitation in dilute Solutions of inosite 

 phosphates, but in concentrated Solutions white needles are formed 

 on long Standing which are insoluble in nitric acid and soluble in 

 water. Preparations f rom seeds retain persistently small amounts of 

 magnesium, several reprecipitations being necessary to get a salt 

 containing a single metal. It is equally difficult to get a preparation 

 free from the hydrogen ion, and it may be said in general that the 

 property of forming acid salts and double salts is very characteristic 

 of inosite-phosphoric acid. The most important contribution to our 

 knowledge of the nature and properties of its salts has been made 

 recently by Anderson. From acid purified by means of barium pre- 

 cipitation and the method described by Hart and Patten, the follow- 

 ing Compounds have been prepared : tri-barium, penta-barium, penta- 

 barium di-ammonium, penta-magnesium, penta-magnesium di-am- 

 monium, tetra-cupric di-calcium, tetra-calcium, penta-calcium, hexa- 

 cupric, octa-silver, and hepta-silver salts. Most of them are white 

 amorphous powders, but the tri-barium and tetra-calcium salts can 

 be reprecipitated in irregulär crystalline form. 



Pure preparations have been made and analyzed by several other 

 investigators. The results of their work are given in Table 2. 



