THE ASH OF PLANTS. 183 



Phosphoric acid 8.2 



Lime 10.5 



Potash 9.1 



Magnesia 1.4 



Sulphuric acid 2.2 



Chlorine 0.9 



Nitric acid . . . .29.7 



Solid Matters 62 



Water 938 



1000 



For use, dilute 15 or 20 c. c. of the above solution with 

 water to the bulk of a liter and add one or two drops of 

 strong solution of ferric chloride. 



The solution should be changed at first every week, and, 

 as the plants acquire greater size, their roots should be 

 transferred to a larger vessel filled with solution of the 

 same strength, and the latter changed every 5 or 3 days. 



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 calcium sulphate before the last dilution, 

 as well as from the precipitation of phosphate of iron on 

 adding ferric chloride. The former deposit may be dis- 

 solved, though this is not needful; the latter will not dis- 

 solve, and should be occasionally put into suspension by 

 stirring the liquid. When the plant is half grown, fur- 

 ther addition of iron is unnecessary. 



In this manner, and with this solution, Wolff produced 

 a maize plant five and three quarters feet high, and equal 

 in every respect, as regards size, to plants from similar 

 seed, cultivated in the field. The ears were not, however, 

 fully developed when the experiment was interrupted by 

 the plant becoming unhealthy. 



With the oat his success was better. Four plants were 

 brought to maturity, having 46 stems and 1535 well-de- 

 veloped seeds. (Vs. St., VIII, pp.190-215.) 



