288 ANNUAL OF SCIENTIFIC DISCOVERY. 



with phosphate of lime and silicate of potash, forms a complete manure, and 

 suffices for the full development of vegetation. Parallel experiments, with 

 nitrate in place of bicarbonate of potash, resulted in the vigorous growth of 

 the sunflower plants, and the formation of 21*248 grams of organic matter, 

 from seeds weighing, as before, only - 107. This 21'111 grams of new veg- 

 etable matter, produced in three months of vegetation, contained 8 444 of 

 carbon, derived from the carbonic acid of the air, and 0*1666 grains of nitro- 

 gen. The 1'4 grams of nitrate of potash applied to the soil, contained 

 0'1969 grams of nitrogen, leaving a balance of 0*0303, nearly all of which 

 was found, unappropriated, in the soil. 



Finally, Boussingault made a neat series of comparative experiments, 

 introducing into calcined sand the same amount of phosphate of lime and 

 carbonate of potash, but different proportions of nitrate of soda, or, in other 

 tvords, of assimilable nitrogen, and watering with water free from ammonia, 

 \)\it containing a quarter of its volume of carbonic acid. The soil divided 

 nmong four pots, each having two seeds of sunflower (H. argophyllus was 

 the species used in all the experiments); the pot 



Ko. 1 received of nitrate of soda, 0-00 grams. 



" 2 " " 0-02 " 



" 3 " " 0-04 " 



" 4 " " 0-16 " 



The result^ of fifty days' vegetation are given in the rate of growth, size and 

 number of the leaves, weight of product, etc. : 



No. 1 made of new vegetable matter, 0-397 grams. 



" 2 " " 0-720 " 



" 3 " " 1-130 " 



" 4 " " 3.280 " 



In No. 2, so little as three milligrams of assimilable nitrogen introduced 

 into the soil enabled the plant to double the amount of organic matter. The 

 proportion of the weight of the seeds to that of the plant formed was, in 



No. 1, as 1 : 4-6 gr. 



" 2, " 1 : 7-6 



" 3, " 1 : 11-3 



" 4, " 1 : 30-8 



In no case did the nitrogen acquired by the plant exceed that of the nitrate 

 added to the soil. 



In the experiments where no nitrate was added to the soil, the two or 

 three milligrams of nitrogen acquired by the plants during three months of 

 vegetation, came, in all probability, from ammoniacal vapors and nitrates 

 existing or formed in the atmosphere. To establish their presence, Bous- 

 eingault arranged an apparatus which detected the production of some 

 nitrates. And, in exposing to the air 500 grams of calcined sand, which 

 had ten grams of oxalic acid mixed with it, in a glass vessel, with an open 

 surface equal to that of one of the flower-pots used in the above experiments, 

 the sand took 0*0013 grams of nitrogen from the air, of which a part was 

 certainly ammonia. 



The object of the researches, of which a summary is given in the second 

 paper, was, to determine the quantity of nitrates contained, at a given 



