MR. R. RIGG'S EXPERIMENTS ON NITROGEN IN VEGETABLE PRODUCTS. 397 



But not only is the nitrogen more abundant in the roots of plants and trees ; the 

 residual also, when compared with the quantity in the trunks, will be found in excess 

 in the roots. 



Now if we admit the principle, that nitrogen is a powerful agent in favourijig che- 

 mical action upon vegetable and animal matter, and that this residual is essential to 

 the healthy performance of every function of the roots, as well as every other part of 

 the plant, and forms, as it were, a most perfect skeleton of the whole ; we have in 

 these roots that which will favour such action in an eminent degree when compared 

 with the other part of the tree. 



It would be leading us into other subjects more extensive than the one now before 

 us, if I were to go into, or treat upon, the chemical action which takes place by the 

 agency of the roots, the compounds formed thereby, the heat produced by such ac- 

 tion, the arrangement of the residual, &c. It will be sufficient, that in following up 

 this part of the inquiry, we state as the result of experiment, that the sap wood is very 

 differently constituted from the more perfect part, the heart wood, an excess of ni- 

 trogen being invariably found in the former. 



Table IV. 



Garb. 



Hydr. 



Oxygen. Nitr. 



Resid. 



Water. Total. 



Nitr. for 

 1000 Garb. 



Young English oak sap wood 



Heart wood of ditto 



Quebec oak sap wood 



Heart wood of ditto 



English elm sap wood , 



Heart wood of ditto 



Acacia sap wood 



Heart wood of ditto 



Cedar from Africa sap wood . . 



Heart wood of ditto 



Chestnut sap wood 



Heart wood of ditto 



55-27 



56-74 



54-05 



54-68 



54-3 



56-5 



52-67 



51-27 



54-33 



59-02 



56-20 



51-37 



100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 

 100 



13 

 4 



7 



3 



39 



17 



13 



12 



10 



9 



9 



7 



It will be unnecessary for me to say that the sap wood more readily passes into a 

 state of decay than the heart wood. Here again the nitrogen and the residual being 

 present in larger quantities in the former than in the latter, we have them exerting 

 their influence as promoters of decomposition. 



We have also the greatest quantities of nitrogen and residual in those timbers which 

 grow the quickest: and further than this ; for directly as the quantity of nitrogen and 

 residual taken collectively, so do we appear to have the decay of timber, all other 

 circumstances being equal. The following is the analysis of several kinds of timber 

 which favour this inference. 



