THE ASH OF PLANTS. 169 
cubic cent., (one fluid ounce,) of this liquid with a liter, 
(or quart,) of water and a single drop of strong solution 
of sulphate of iron, and employ this diluted solution to 
feed the plant. 
Wolff’s solution, thus prepared, contained in 1000 parts 
as follows, exclusive of iron: 
Phosphoric acid - - 8,234 
Lime - 10.370 
Potash - - = 9,123 
Magnesia -  - = 1.408 
Sulphuric acid- —- 2.254 
Chlorine - - = 0.885 
Nitric acid - - - 29.703 
Solid Matters - - - 61.972 
Water - - - 938.028 
1000. 
This solution was diluted to a liquid containing but one 
part of solid matters to 1000 or 2000 parts of water. 
The solution should be changed every week, and as the 
plants acquire greater size, their roots should be trans- 
ferred to a larger vessel, filled with solution of the same 
strength. 
It is important that the water which escapes from the 
jar by evaporation and by transpiration through the plant, 
should be daily or oftener replaced, by filling it with pure 
water up to the original level. The solution, whose prep- 
aration has been described, may be turbid from the sepa- 
ration of a little white sulphate of lime before the last dilu- 
tion, as well as from the precipitation of phosphate of iron 
on adding sulphate of iron. The former deposit may be 
dissolved, though this is not needful; the latter will not 
dissolve, and should be occasionally put into suspension by 
stirring the liquid. When the plant is half grown, further 
addition of iron is unnecessary. 
In this manner, and with this solution, Wolff produced 
8 
