NOV. 22 , 1915 
Occurrence of Manganese in Wheat 
35i 
in the soil is about 0.10 per cent, calculated as elemental manganese. If 
the manganese be an accidental constituent, as is usually held to be the 
case, its presence must be due to the supply in our soil, but the amount 
taken up appears to be very nearly constant, irrespective of the soil. 
In order to ascertain whether the manganese is universally present in 
the wheat kernel and to determine in what quantity it is usually present, 
I obtained samples of wheat from a number of localities in the United 
States and Canada and from three European countries. While man¬ 
ganese is probably present in every cultivated soil, it is very rarely the 
case that it constitutes more than a small fraction of 1 per cent, while 
iron is usually present in much more considerable quantities. The 
amount of manganese present in the soil bears no relation to that of the 
iron. In the soil on which our wheat samples were grown, the metallic 
iron found by a mass analysis of the soil was a trifle over 30 times as 
great as the total amount of manganese. The analytical results given 
subsequently show that this is not the ratio in which the two elements 
are present in the kernels and not even in the green plant or in the ripe 
straw. It does not seem probable that the manganese has been absorbed 
simply because it existed in the soil associated with iron, if this indeed 
be the case in any strict sense, for the association might be with calcium 
as well as with iron. 
The method used in determining manganese in grain was to take 
10 gm. of ground, air-dried wheat, dissolve it in concentrated nitric acid, 
and evaporate the solution to a thick, gummy, brown mass. This was 
then heated over a free flame till all volatile matter was expelled. The 
dish was then placed in a muffle and most of the carbon burned off. 
After removal and cooling, a few (4 or 5) cubic centimeters of concen¬ 
trated sulphuric acid were added. The sides of the dish were washed 
down with a little water and the solution evaporated at last on a sand 
bath till vapors of sulphuric acid escaped freely. After cooling, this was 
taken up with water, boiled, arid filtered into a 200 c. c. flask. The 
residue on the filter was burned, taken up with a little sulphuric acid as 
before, and the solution filtered and added to the first filtrate. The 
combined filtrates should be about 150 c. c. in volume and contain about 
5 per cent of sulphuric acid. A little silver sulphate (from 25 to 30 mgm.) 
was next added and then 4 or 5 gm. of ammonic persulphate. The solu¬ 
tion was placed on a boiling water bath and allowed to stand as long as 
the color deepened. It was then cooled, made up to volume, and com¬ 
pared with the standard, which had been prepared in the same way. 
All reagents should be tested by making a blank. 
Manganese in the straw was determined in the same way, except that 
the silica was removed by evaporating in a platinum dish with the addi¬ 
tion of hydrofluoric acid. 
In Tables I and II are given the variety, the fertilizer applied, and 
the percentage of iron and manganese found in wheat from Colorado and 
