On the Food of Plants. 
553 
and magnesia, contained a little of each. Another portion evaporated 
to dryness, and ignited left a minute residue of chloride of potassium. 
Precipitated earthy phosphates dried, powdered, and fused, with ex- 
cess of carbonate of soda ; fused mass treated witii water, and placed on 
filter. Solution examined for phosphoric acid, and insoluble matter for 
lime, magnesia, and oxide of iron. 
From the above it was inferred that the soluble portion of the ash 
consisted of sulphate of potash, with a little chloride ; and the insolul)le 
matter of siliceous scales (to be further examined), phosphates of lime 
and magnesia, small portions of carbonates of those earths, and a trace 
of potash. 
Quantitative Analysis. 
20 grains of ash lost by gentle ignition . . .0*2 grains. 
Water added, boiled, and filtered ; solution acidulated with 
nitric acid, evaporated to dryness, acidulated water 
poured on the residue, and filtered : silica washed, 
dried, and ignited . . . . . . 0.3 „ 
Acid solution mixed with chloride of barium, boiled and 
filtered: sulphate of baryta, ignited . . . 3'8 „ 
= 2 ' 9 grains of sulphate of potash. 
Matter insoluble in water, gently ignited, weighed . 
16 
•2, 
Treated with dilute hydrochloric acid, and filtered : matter 
insoluble in acid, ignited 
14 
o 
Acid solution mixed with ammonia, filtered ; phosphates, 
ignited 
1' 
' 5 
To solution oxalate of ammonia added, filtered : carbonate 
of lime 
0 
•15 
Hence, — 
[Sulphate of potash 
2 
•9 
Soluble salt . 3' oj 
Chloride, by difference 
[Silica .... 
0' 
0 
4 
•3 
1 Siliceous scales 
14 
■ 2 
1 
Insoluble part 16* 2< 
[Phosphates 
1 Carbonate of lime 
1 
0 
5 
■15 
1 
[Potash, magnesia, &c. 
()■ 
•35 
Water 
0 
■2 
20- 
0 
Grain. — Portion of ash treated with water, solution distinctly alkaline ; 
refused to filter. Niti-ic acid added, no effervescence, but greater portion 
dissolved ; filtered, black sandy matter remained. 
Solution mixed with ammonia and warmed, by which a very abundant 
white granular precipitate was thrown down ; this washed, dried, isnited, 
and examined proved to be a mixture of phosphate of magnesia with a 
little phosphate of lime : — Ammoniacal solution contained neither lime, 
magnesia, sulphuric nor hydrochloric acids ; a portion evaporated to dry- 
ness and ignited yielded a residue consisting of phosphate of potash. 
