1917] AGEIOULTUBAL CHEMISTET AGHOTECHNY. 11 



comi.uuud between sodi^im hydroxid and glucose from a study of the electrical 

 conductivity of such a mixture. 



An attempt to modify Barfoed's solution for quantitative work was unsuc- 

 cessful. 



[Methods for analysis of wheat grain, plants, and straw], W. P. Headden 

 {Colorado Sta. Bui. 219 {1916), pp. 124~127).—The following procedures were 

 used in the study noted on page 38. 



For oxidizing the wheat grain 25-gm. samples were treated with concentrated 

 nitric acid in separate portions of from 15 to 20 cc. The material foams 

 strongly and care mu.st be taken that none is lost during the oxidation. Silica 

 dishes were used, but it was found that small flakes sometimes broke off and 

 were weighed as silica. The amount, however, was usually extremely small 

 and negligible. 'Wlien 50 cc. of nitric acid had been added the residue was 

 evaporated to a gummy mass and charred over a free flame, and finally heated 

 in the nnifTler. To remove the small portion of carbon remaining the mass 

 was treated with aqua regia, the solution evaporated to dryness, the residue 

 treated with hydrochloric acid, and filtered. The filter which contained 

 the residual carbon and silica was returned to the dish, burned, and treated 

 as before. In the solution of the ash, the iron, calcium and magnesium were 

 precipitated as phosphates, the iron weighed as phosphate, the calcium as 

 oxid, and the magnesium as pyrophosphate. 



The filtrate which contained the alkalis was concentrated and acidulated 

 with hydrochloric acid if necessary, an excess of ferric chlorid was added, 

 and then ammonia in excess to precipitate the ferric oxid and with It the 

 phosphoric acid. The precipitate was filtered off, washed, dissolved in hydro- 

 chloric acid, and again reprecipitated. The united filtrates contained the 

 alkalis as chlorids and were treated in the usual manner. 



The chlorln was determined in a separate 10-gm. sample which was dissolved 

 in a mixture of nitric acid and silver nitrate. When completely dissolved, 

 water was added, which increased the bulk of the white flocculent precipitate 

 of silver chlorid. It was filtered off, washed, the mass mixed with a mixture 

 of potassium nitrate and sodium carbonate, transferred to a nickel dish 

 containing 2 or 3 gm. of the nitrate-carbonate mixture, the mass covered 

 with the mixture, and heated until completely fused. The fused material 

 was dissolved in water and the usual determination for chlorin followe<l. 



The phosphorus was determined in a 10-gm. sample which was dissolved in 

 concentrated nitric acid, after which 1.5 gm. of magnesium oxid was added 

 and the whole evaporated to a brown, gummy mass, and ignited. The cooled 

 mass was treated with dilute nitric acid, evaporated again, and the combustion 

 completed. It was then dissolved in nitric acid, evaporated with sulphm-ic 

 acid to separate silica, and the phosphoric acid precipitated as molybdate and 

 finally weighed as magnesium pyrophosphate. 



The sulphur was determined in a manner similar to the phosphorus deter- 

 mination, except that ordinary gas could not be used during the oxidation. 



The manganese was determined colorimetrically and the samples oxidized 

 and ashed by means of nitric acid as in the other procedures. The combustion 

 was completed in the muffler and the residue taken up with sulphuric acid and 

 filtered. The solution should contain about 5 per cent sulphuric acid. A few 

 milligrams of silver sulphate and a few grams of ammonium persulphate were 

 added and the solution heated until the color had developed completely. 



Some difiiculties were experienced In detei-mining the ash of the wheat plant 

 and wheat straw. For the ash determination 10 gm. of the ground straw or 

 plant was thoroughly charred and extracted three times with boiling water. 



