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 - - - - 1.403 

 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 phosj)hate of iron 

 on adding suljDhate of iron. The former deposit may be 

 dissolved, though this is not needful; the latter will not 

 dissolve, and should be occasionally jjut 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 



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