THE SOURCES OF THE NITEOaEN OF VEGETATION, ETC. 
495 
Since it would appear that, under certain circumstances. Ozone is formed in the im- 
mediate wcinity of some plants, it remains to consider the possibility of its acting, in an 
indirect manner, as a source of combined Nitrogen to our experimental plants — that is, 
through the agency of the materials involved in the experiment — and thus compromising 
our result in regard to the question of the appropriation, by the plant itself, of free or 
uncombined Nitrogen. It might so act : — 
1. By becoming absorbed by the water that condenses uhthin the vessel enclosing the 
plant, and then oxidizing the free Nitrogen dissolved in the water. 
2. By being absorbed by the soil — either directly from the air of the enclosing appa- 
ratus, or from the condensed water returned to the soil — and then, in connexion with 
it, as a moist, porous, and alkaline body, forming nitrates in the manner referred to 
by Pelouze and Fkemt*, in their remarks upon the experiments of Cloez which we 
have shortly described at p. 465 of this paper. 
3. By passing down in solution in water, or in the gaseous state, to the older and 
decomposing parts of the roots, and there forming nitric acid by the oxidation either of 
the free nitrogen contained in the older cells, or of that evolved in decomposition. 
These questions have not been so fully investigated as, considered as independent 
subjects of inquiry and with reference to the results obtained by Schoxbeix and others, 
would be desirable. But so far as they can have a bearing upon the sources of error in 
our experiments upon the question of the assimilation of free Nitrogen by plants, they 
have received our careful consideration. 
C. — Experiments on the action of Ozonized air on decomposing Organic matter^ 
and porous and alkaline substances. 
Experiments were made to ascertain the influence of Ozone upon organic matter, and 
certain porous and alkaline bodies, under various circumstances. The action of ordinary 
air upon sticks of phosphorus was had recourse to as the source of the Ozone. The 
arrangement was as follows : — Three large glass balloons (carboys), each of about 
40 litres capacity, were connected together by glass tubes which passed through 
stone-ware stoppers fitted into their mouths, the joints being made tight with calcined 
gypsum cement. The bottom of each vessel was covered with water to the depth of 
about half an inch, so that, when pieces of phosphorus were put in, they were partly 
covered with the fluid. A tube, which could be opened or closed at pleasure, was fixed 
through each stopper for the supply of water, and fresh phosphorus, as needed. An 
Allen and Pepys gasometer, capable of holding about 2 cubic feet of air, was con- 
nected by a glass tube with the first of the series of vessels; and by its means, 
air could be forced in a continuous stream through the three vessels containing the 
phosphorus. On passing out of the last of them it was led through a wash-bottle, and 
then into a glass vessel, from which, by means of a number of glass tubes passing from 
it, it was distributed into bottles containing the substances to be submitted to the action 
* Traite de Chimie Generale, tome sixieme, p. 343 (1857). 
3 Y 
MDCCCLXI. 
