A Study of Colorado Wheat 
f 
A Study of Colorado Wheat 127 
The separation of the bases and the determination of the alkalis were 
effected just as in the case of the wheat. 
Phosi>horus 
I took 25 grams of finely ground straw, disintegrated thoroughly with 
concentrated nitric acid, added 1^/^ to 2 grams magnesic oxid, evaporated 
down, and finally heated to introduce the combustion. The residue was 
not white, but contained much unbumed organic matter. Nitric acid was 
added and the previous operation repeated. The residue, if still too dark, 
was burned white in the muffle. The thoroughly burned mass was dis¬ 
solved in nitric acid, a few cubic centimeters of concentrated sulfuric acid 
added and evaporated, at last, on the sand-bath till the sulfuric acid fumes 
began to escape, the dish was then placed in a hot-air oven and kept at 
160® or higher to separate the silicic acid. The phosphoric acid was separ¬ 
ated from this solution with the usual precautions by ammonic molybdate 
and eventually weighed as magnesic pyrophosphate. 
As the silicic acid may give some trouble, this may be removed by 
digesting the disintegrated straw with 10 to 15 c.c. of strong hydrofluoric 
acid before the addition of the magnesic oxid. 
Sulfur was determined in essentially the same manner as the phos¬ 
phorus, except that gas cannot be used unless free from sulfKir, and the 
magnesic oxid, which must not be heated too strongly, was taken up with 
hydrochloric acid and evaporated to separate silicic acid. 
The manganese in the straw was determined in ten-gram portions in 
the same manner as in the wheat, except that to the thoroughly disinteg¬ 
rated mass was added a few c.c., 5 or 6, of 'concentrated hydrofluoric acid 
to remove the silica; the mass was then heated for! 10 minutes, when I add¬ 
ed 5 c.c. concentrated sulfuric acid and continued the evaporation, heating 
at last over the free flame. The residual mass of carbon usually burned 
'out readily in the muffle. 
