New York Agkicultukal Experiment Station. 147 



acid reaction. The solubility corresponded with that previously 

 observed. Yield 7.7 gm. 



For analysis it was dried at 105° in vacuum over phosphorus 

 pentoxide. 



0.2914 gm. subst. gave 0.0440 gm. HoO and .1026 gm. CO2. 

 0.1667 gm. subst. gave 0.0977 gm. Ba S04 and 0.0960 gm. Mg2P207 . 



For C6H6(OH)4 02(P206HBa)2 = 770.7 



Calculated C 9.34: H 1.55: P 16.08: Ba 35.64 per ct. 



Found C 9.60: H 1.68: P 16.05: Ba 34.48 per ct. 



The barium was found to be a little low but this is compensated 

 for through a slightly high carbon content; moreover it is sometimes 

 difficult to obtain amorphous salts of this kind which show closer 

 agreement than the above. The analysis leaves no doubt that the 

 substance was the barium salt of the ester in question. It will be 

 noticed that the dipyrophosphoric acid ester is isomeric with the tetra- 

 phosphoric acid ester of inosite previously referred to. Lack of time 

 has prevented the determination of the free alcoholic (OH) groups 

 in the inosite ring in either of these compounds. Experiments along 

 this line are contemplated, however. 



That the reaction between the inosite and the pyrophosphoric acid 

 actually occurred along the hues discussed above may be judged 

 by the amount of water given off. To determine this point 0.36 

 gm, inosite (one mol.) and 1.06 gm. pyrophosphoric acid (3 mol.) 

 both previously dried at 100° C. were heated in a small flask in oil 

 bath at 200°-220° under the same conditions as in the above experi- 

 ment. The water, which began to come over at a temperature of 

 about 200°, was collected in a weighed calcium-chloride tube. The 

 aqueous vapors were removed by means of the suction pump but 

 no special effort was made to secure quantitative results. The water 

 obtained weighed 0.0494 gm. whereas the quantity calculated for 

 2 mol. H2O is 0.072 gm. The amount obtained is therefore only 

 about 68 per ct. of the theory. 



PREPARATION OF THE FREE DIPYROPHOSPHORIC ESTER. 



The air-dried barium salt of the ester (4 gm.) was suspended in 

 water and decomposed with a slight excess of sulphuric acid, the 

 barium sulphate was removed and the solution precipitated with 

 copper acetate. The copper salt was filtered off, thoroughly washed 

 in water, suspended in water and decomposed with hydrogen sul- 

 phide. It was found impossible to remove the copper sulphide com- 

 pletely by filtration as it formed a colloidal solution, but by acidify- 

 ing with a few drops of hydrochloric acid and heating to boiling the 

 copper sulphide precipitated. After filtering, the filtrate was evap- 

 orated several times in vacuum for the removal of the hydrochloric 



