THE SOURCES OF THE NITROGEN OF VEGETATION, ETC. 



489 



Table III. — Showing the amount and composition of the Gas given off into 

 a Torricellian vacuum, by plants exposed to sunlight. 



Date. 



How manured, &c. 



Total 

 Gas col- 



li'fi. J. 

 cub. 

 cents. 



Per cent. 



Nitro- 

 gen. 



Oxygen. 



Car- 

 bonic 

 acid. 



Oxygen 



and 

 Carbonic 



acid, 



Wheat (whole plant), 1858. 



June 

 June 

 June 

 June 

 June 

 June 



22. 'Unmanured. 



23. Unmanured. 

 30. Unmanured. 

 22. 

 23. 

 25. 



Mineral and Ammonincal manure. 

 Mineral and Ammoniacal manure. 

 Mineral and Ammoniacal manure. 



26-35 

 22-99 

 27-21 

 26-24 

 21-85 

 21-24 



Grass (whole plants), 1857- 



August 15. Mineral and Ammoniacal manure: second crop 

 August 15. Mineral and Ammoniacal manure: second crop 

 August 15. Mineral and Ammoniacal manure 

 August 17. Mineral and Ammoniacal manure 



August 18. 

 August 18. 



Mineral and Ammoniacal manure 

 Mineral and Ammoniacal manure : 



second crop 



second crop . 



second crop 



second crop 



17-90 

 22-92 

 23-44 

 24-93 



20-12 

 19-77 



Beans, 1858. 



July 

 July 

 July 



July 



12. 

 12. 

 15. 

 15. 



Mineral manure ; almost podding 



Farm-yard manure; almost podding 



Unmanured; almost podding 



Mineral and Ammoniacal manure ; almost podding. 



44-3 

 45-8 

 25-9 

 30-9 



71-11 

 73-14 

 82-63 

 70-55 



18-28 

 10-26 

 15-S3 

 20-71 



10-61 



16-60 



1-54 



8-74 



28-89 

 26-86 

 17-37 

 29-45 



The general accordance in the proportions of Nitrogen found throughout this Series, 

 together with their general approximation to the amounts observed in Series 2 (Table II.), 

 and the consequent similarity in range of the sums of the two remaining gases — carbonic 

 acid and oxygen — point to the character of the change which has taken place, by virtue 

 of which the proportion of carbonic acid is diminished, and that of oxygen increased. 

 The variations in the amounts are, nevertheless, somewhat considerable ; and we feel 

 that it would be requisite to exercise considerable caution in attempting to refer them 

 to any other than accidental circumstances beyond our control. There can be no doubt, 

 however, that the carbonic acid, shown to exist in the plants in the shade, has yielded 

 the oxygen evolved when in the sunlight. But the mutual relations of the two gases will 

 be more clearly brought to view by a consideration of the results yet to be adduced. 



Experiments, Series 4. 

 These experiments, as well as those of the succeeding Series, were arranged to show 

 the influence of the time of action of the sunlight on the plant, upon the relative pro- 

 portions of carbonic acid and oxygen. 



In the Series of experiments now under consideration, duplicate quantities of the 



3x2 



