428 



Journal of Agricultural Research 



Vol. III. No. s 



Two of the corrected residues were treated with hydrofluoric acid, but 

 no decrease in weight resulted. 



Barium was also determined by dissolving the barium phytate in about 

 200 c. c. of water with a few cubic centimeters of dilute hydrochloric acid. 

 Twenty c.c. of 0.4 N sulphuric acid were added to the boiling solution, 

 the whole was boiled about half an hour, and then set aside on a hot-water 

 bath for several hours. The precipitate, after standing overnight, was 

 filtered, washed, and ignited. On weighing, then fusing and reprecipitat- 

 ing the barium, as was done above, a slight increase in weight was ob- 

 served. The filtrates from the barium precipitates after fusion were united, 

 evaporated to small bulk, acidified with nitric acid, and ammonium molyb- 

 date added. A yellow precipitate was found after standing, and the 

 phosphoric acid then obtained was weighed as magnesium pyrophos- 

 phate. By fusing the impure residues amounting to from 0.2754 to 0.351 1 

 gm., the magnesium pyrophosphate obtained was found to be 0.0181, 

 0.0092, 0.0095, arid 0.0074 gm. 



The weight of the residues of barium sulphate before and after correc- 

 tion for phosphate is given in Table II. 



Table II. — Quantity of barium sulphatt "■ and viagtiesium pyrof>hosphale precipitated 

 from a solution of barium phytate 



" Not calculated to water-free basis. 



The filtrate containing the phytic acid from which the barium was 

 precipitated by the foregoing method still contained a few tenths of a 

 per cent of barium. On evaporating to small bulk or igniting, a small 

 precipitate of barium sulphate was obtained. It would appear that 

 phytic acid has some solvent action on barium sulphate. 



The fact that phosphoric acid was precipitated along with the barium 

 sulphate by very dilute sulphuric acid suggests that the composition of 

 phytic acid as determined by Anderson may have been affected. The 

 phosphorus, if carried down with the barium sulphate, would cause a low 

 phosphorus content in the remaining solution. 



It was attempted to determine barium by first igniting the salt, but a 

 white ash could not be obtained, and the residue was extremely difficult 

 to dissolve after ignition. Phosphoric acid was best determined by the 

 Neumann method, filtering off the barium sulphate formed on dilution. 

 The results were about o.i per cent lower when determined by precipitat- 

 ing the barium with dilute sulphuric acid and evaporating the phytic 

 acid thus obtained vrith magnesium nitrate and igniting and adding 

 the phosphorus anhydrid found in the fused barium residue. 



Carbon and hydrogen were determined by the regular combustion 

 method, passing oxygen through the apparatus during the burning. In 

 each case the black ash remaining was ground up with potassium 

 dichromate and rebumed. 



