526 
On the Food of Plantx. 
Siliceous scales, on analysis, gave : — 
13-1 
0-5 
0-5 
0-1 
14-2 
Soluble salt converted into chloride, and examined for soda: — 
2" 8 grains ignited cliloridc gave 8*8 grains ilouLle chloride of 
platinum and potassium; corresponding to 2" 699 grains of 
pure chloride of potassium. 
Grain : — 
1000 grains of wlieat gave of ash, hy incineration, 14 "5 grains. 
Or, 1 "45 per cent. 
10 grains gave, on analysis : — 
Phosphates of magnesia and lime . 3 •'7 
Allvaline phosphate (by difference) . .^(' i 
Charcoal,- sandy matter, &c. . .0 9 
10-0 100 
This result must be looked upon as approximative only. There 
are obstacles in the way of a very exact analysis of these grain 
ashes, the chief of which are the difficulty of procuring a sufficient 
quantity to operate on, and the impossibility of separating by the 
filter the soluble from the insoluble salt, owing to the peculiar 
character of phosphate of magnesia. The presence of a large 
amount of soluble phosphate was rigidly demonstrated, although 
the c^uantity of that substance could only be conveniently obtained 
by difference; a method liable to a certain degree of error. It 
is, no doubt, this alkaline phosphate which renders the incinera- 
tion of this and other kinds of corn so excessively slow and trou- 
blesome, by causing fusion to take place unless the heat be regu- 
lated with the utmost care. 
2. Wheat from Berkshire; land enriched by farmyard manure. 
Straw : — 
500 grains of entire straw gave of ash . 23*0 grains. 
500 . . . . . 23'3 „ 
The mean gives 4'G3 per cent. 
20 grains, on analysis, gave : — 
Sdica 
Phosphates 
Potash 
Ciiarcoal, &c. 
Ill 100 parts. 
31 
54 
9 
