-8 7 - 
this line; and further because of the tedious character of 
the operations, only a few samples were chosen in which to 
attempt the more accurate determination of these com¬ 
ponents, sulphuric and phosphoric acids. Two samples of 
roots and one of leaves were chosen for this work; the 
leaves because of the large amount of sulphuric acid, and 
the roots because of their relative richness in phosphoric 
acid as well as low percentage of ash. 
In the following table, the first column gives the per¬ 
centage of sulphuric and phosphoric acids found in the ash, 
and the second column gives the percentage which the 
ash should contain to correspond to the percentage found 
in the plant. 
Leaves:— 
Sulphuric acid. 10.841.12.843 
Phosphoric acid. 3-459. 3.600 
Inside portion of roots:— 
Sulphuric acid. 4.881. 8.091 
Phosphoric acid .16.032.15.982 
Whole roots:— 
Sulphuric acid. 5.093 . 7-653 
Phosphoric acid. 10.270.10.048 
Here we observe a loss of 2.001, 3.210, and 2.561 per 
cent, of sulphuric acid; while the phosphoric acid determi¬ 
nations agree as well as could be expected. The prepara¬ 
tion of the ash samples has been given. The determina¬ 
tion directly from the air-dried samples was made as fol¬ 
lows: from ten to thirty grams of the sample, according to 
the amount of ash it had yielded, was placed in a silver dish 
and thoroughly saturated with a solution of a mixture of 
ten grams potassic hydrate to two and one-half grams of 
nitre and ignited with subsequent addition of weighed por¬ 
tions of nitre until the mass had become white. The sul¬ 
phuric acid in the potassic hydrate and nitrate was determ¬ 
ined and deducted from the total found. Every precaution 
heretofore given was exercised in these determinations of 
sulphuric acid, and equally so in the case of the phosphoric 
acid, which was thrown down from the filtrate from the 
baric sulphate as ferric phosphate and then by amnionic 
molybdate as usual. 
These results make evident the error in the sulphuric 
acid determinations by the method of direct incineration as 
given for these samples; but show no loss for the phos¬ 
phoric acid. These were the primary objects of the deter¬ 
mination, but the samples were chosen with the purpose of 
giving duplicate determinations of these constituents, partic- 
