40 



On the Inorganic Constituents of Plants, 



produced by the Nitrate of Soda on the formation of azotised 

 matter with that produced by the use of another salt of the same 

 alkali, not containing nitrogen. The following was the result. 



In the experiment with Tobacco just described, a considerable 

 effect was produced by the Nitrate of Soda ; a given quantity of 

 leaves contained less water, and more organic and inorganic matter, 

 than those which had not been manured with the nitrate ; and it 

 is evident that the nitrated plant had absorbed a larger quantity of 

 inorganic matter, in proportion to its weight, than the other had, 

 because on comparison it appears that the dry leaves of the former 

 contained about a twentieth part more inorganic matter than the 

 latter. In the case of the lettuces a very different effect was pro- 

 duced. In this, the plants manured with Carbonate and Nitrate of 

 Soda, grew more rapidly than those manured with Rotten Dung 

 alone ; hence, they contained a larger proportion of water, and a 

 smaller quantity of inorganic matter. This more vigorous growth 

 was apparently not connected with any increased absorption of 

 inorganic substances, because in both cases where the saline manure 

 was applied, the dry plant contained nearly a twentieth less inor- 

 ganic matter than that only manured with Dung. 



A fourth experiment was made on a far more extended scale, 

 with Potatoes. A number of tubers of the Bread-fruit potato 

 were planted, each in the centre of a square yard of ground, and 

 manured with various saline and other manures. The tubers taken, 

 were as nearly as possible alike ; they were planted on the 28th of 

 April, the various manures being applied at the time the tubers 

 were set. The stems or haulm were gathered, and the tubers 

 taken up in October. The tubers were planted eight inches below 

 the surface of the ground, each being placed in the centre of a 

 square yard, the surface soil of which was removed to the depth of 

 two inches ; the manures were then spread, and the two inches of 



