38 On the Inorganic Constituents of Plants. 



Green or outer leaves of Savoy; as before. 



It is evident that no definite conclusions can be drawn from this 

 series of experiments. All the plants included in the foregoing 

 tables were manured with 1800 or 2000 grains of the substance 

 applied, but as these manures were merely spread on the surface 

 of the soil, and were much protected from rain by the leaves of the 

 young plants, a portion remained on the surface of the soil to the 

 last ; this in part accounts for the very trifling effect produced. 



At the same time that these experiments were tried, some others 

 were made with plants less able to bear large quantities of saline 

 manures than savoys and most glaucous leaved plants are. A num- 

 ber of plants of common broad leaved Tobacco were manured 

 with Nitrate of Soda, the quantity employed increasing from 3oz. 

 up to 2 lbs, to each plant. Tobacco was selected for experiment 

 because it is one of those plants which most commonly contain 

 salts of Nitric acid ; it was hence reasonable to expect that a top 

 dressing of the Nitrate of Soda would produce a beneficial effect 

 and also that a comparatively large quantity of that salt might be 

 applied without fear of injury. Those plants which had received 

 4, 8, 12, and 16 oz. respectively of Nitrate of Soda were all 

 rendered more vigorous in their growth and looked greener 

 and far more flourishing than those not so manured ; their luxu- 

 riance being nearly in proportion to the quantity of the salt they 



