nium thiocyanate as indicator. The barium salt can be obtained in 

 the form of spherical masses consisting of microscopic needles ; other 

 salts with inorganic bases crystallize much less readily or not at all.. 

 Posternak describes, however, several double salts which were crystal- 

 line. The only organic base found so far that forms readily crystalline 

 salts with inosite hexaphosphoric acid is strychnine, as was first shown 

 by Clarke (1914). 



PROPERTIES OF THE SALTS OF INOSITE HEXA- 

 PHOSPHORIC ACID 



The alkali salts of the acid have not been obtained in crystalline 

 form. The magnesium and calcium salts have no definite crystalline- 

 structure, but are obtained under certain conditions as small spherules 

 or globules of uniform size. Posternak obtained double salts of the- 

 acid with alkali and alkaline e'arths which crystallized in small needles.. 

 Of the salts with inorganic bases the acid barium salts crystallize most 

 readily. If the barium salt dissolved in dilute hydrochloric acid is pre- 

 cipitated with alcohol an amorphous precipitate is formed which, how- 

 ever, on standing in contact with the aqueous alcoholic mother-liquor,, 

 usually assumes the crystalline form after a few hours. These crystals 

 are minute rosettes consisting of microscopic needles. The same 

 shaped crystals may be obtained by carefully adding alcohol to the 

 dilute hydrochloric acid solution of the barium salt until a slight 

 cloudiness appears. The solution is now filtered and allowed to stand,, 

 when the salt separates out in the above-mentioned crystalline form. 

 These salts are crystalline, but they do not contain a constant quantity 

 of barium unless an excess of barium chloride is added to the solution 

 before crystallization begins. It is also necessary to provide as nearly 

 identical conditions as possible as to concentration of the salt and 

 acid ; slight variation in the amount of free hydrochloric acid present 

 will cause'a difference of 1.5 to 2 per cent, in the amount uf barium in- 

 the crystalline salt. Similar crystalline barium salts are obtained" 

 when solutions of the barium salt in dilute hydrochloric acid are heated 

 nearly to boiling, only in this case the salt contains about 4 per cent- 

 more barium than when separated from the acid alcohol mixture men- 

 tioned above. A salt of similar crystal form and composition is also- 

 formed when the dilute hydrochloric acid solution of the salt is nearly- 

 neutralized with dilute barium hydrate, filtered and allowed to stand.. 

 The first salts mentioned above correspond to tribarium inosite hexa- 

 phosphate, C 6 H 12 24 P 6 Ba 3 , and the last mentioned salts correspond' 

 to heptabarium inosite hexaphosphates, (CeHnO^Pu), Ba r , or else 

 to equimolecular mixtures of tribarium and tetrabarium inosite hexa- 

 phosphates, C 6 H 12 O 24 P Ba 3 -+- C 6 H 10 O 24 P Ba 4 . The tribarium ino- 



16 



