408 ME. J. B. LAWES, DB GILBEET, AND DB. imi.ii OB 



A number of experiment according to the first of these methods has been made by 

 Reiset. He submitted nitrogenous animal and vegetable substances to decomposition 

 under an enclosing vessel in ordinary air, into which hi p: i <l oxygen as that of the 

 air was consumed. 1 1 is result was, thai the amount of Nitrogen in the air was gradually 

 increased, lie does not appear, however, t" have completed tin- inquiries on this sub- 

 ject which he proposed to undertake. 



The second method has been followed by M. ('-. Vims. The conclusion lie arrived at 

 was, that in the decomposition of several nitrogenous vegetabL . about one- 



third nl' their total Nitrogen was evolved in the free state. 



The losses of Nitrogen which M. Boussingai lt's experiments on the question of the 

 assimilation of free Nitrogen by plants indicated, when he used nitrogenous organic 

 matter as manure, rendered it desirable to investigate the subject in its bearings upon 

 the conditions provided in our own experiments on that question. The following plan 

 was adopted : — 



A given weight of nitrogenous organic matter, the percentage of Nitrogen in which 

 had been previously determined, was mixed with burnt soil, or pumice, prepared as for 

 the experiments on the assimilation of Nitrogen by plants (p. 471), and put into a bottle 

 of about 300 cub. centims. capacity, as shown at B, fig. 8, Plate XII. A proper quantity 

 of water was added; and then the bottle was closed with a cork, through which were 

 tightly fitted two bent glass tubes, which passed externally hi opposite directions. One 

 of these tubes was connected with an eight-bulbed apparatus A, containing sulphuric 

 acid, for the purpose of washing air drawn through it into the rest of the apparatus. 

 The other tube, passing from B in the opposite direction, was connected with a similar 

 eight-bulbed apparatus C, containing a solution of oxalic acid. From this again passed 

 a tube extending, through a cork, to the bottom of a second bottle D (similar to B), 

 which contained some sulphuric acid. Through the cork of the bottle D another tube 

 E also passed, but it did not dip into the sulphuric acid. It is obvious that, on drawing 

 the air from D by means of the tube E, a current of air would pass inwards through 

 the sulphuric acid in A, into the bottle B, then through the oxalic acid in C, and so on. 

 In this way, the air of the vessel B, containing the decomposing organic matter, could 

 be renewed at pleasure by fresh air, washed free from ammonia. At the same time, any 

 ammonia evolved from the decomposing organic matter was drawn into the eight-bulbed 

 apparatus C, and there absorbed by the oxalic acid. At the termination of the experi- 

 ment, the combined Nitrogen remaining in B, and that retained in the form of ammonia 

 in the oxalic acid in C, were determined. The difference between the total amount of 

 combined Nitrogen so found in the products and that originally contained in the organic 

 substance submitted to decomposition, is taken to represent the amount of nitrogen 

 given off, in the free state, during the process. 



