NUTRITION OF VEGETABLES. g5 



the bottle, without having had any fresh air admitted to it. 



Accordingly I procured six large flint glass bottles, most of 



which were square: filled them iu part with very fine white 



sand, which I deprived of all calcareous earth by washing 



with weak muriatic acid; and moistened this with distilled ^jj.j. ., 



water. The remainder of the bottle was filled with atmos- presence of 



pheric air freed from carbonic acid. carbonic acid. 



In these bottles having sowed 460 seeds of white mustard, 

 I closed them very accurately, and plained them a few inches 

 deep in a moist soil. Vegetation soon commenced, and con- They grew, , 

 siderable vertiure was produced*. After six weeks growth 

 my plants were liberated from their prisons, washed with 

 great care, and dried. Tn this state they weighed J) gram. 

 [140 grs.] I filled a phial with them, which terminated in a 

 narrow tube, and exposed it gradually to a strong heat. 

 Thus I obtained 4 gr. 8 dec. [74 grs.] of coal. But as I 

 supposed this coal might still contain a fittle sand, I incine- carbon 

 rated it, and found 3 gr. 3 dec. [51 grs.] of very alkaline 

 ashes. Consequently there was if gr. [23 grs.] of pure 

 carbon. 



In a very small vessel I distilled 460 white mustard seeds, 

 and from this highly hidrogenatcd seed I obtained only 4 gr, 

 [6-2 grs.] of coal, which lost near half its weight by calcin- In larger quan- 

 ation. Hence it follows, that 460 mustard seeds acquired in ^^^^^^ ^^'"^ '^* 

 close vessels upwards of a gramme [l5j grs.] of pure carbon, 



• It may be supposGd, that these seeds did not germinate with as r„. 

 1. • .... . rr,, . , r , , , The plants 



much vigour, as it in the open air. This however 1 do not thtnk must grew weakiy 



be ascribed to the want of oxigen ; for by trial of the air with a sulphuret ij^^ ^^^ f q_ 



before and after the experiment, its proportions appeared to be nearly the want of oxi- 



same. This is agreeable to the experiments of Hassenfratz, who con- S^n. 



vinced himself, that plants do not diminish the quantity of oxigen in a 



confined atmosphere : and I am inclined to think, that oxigen acts on 



plants merely as a stimulant, which is not indispensable, for Homber* "■ 



found diiferent seeds germinate in the vacuum of an airpump. The 



principal cause, that prevents the complete dcvelopement of plants in 



close vessels, appears to me to be owing to their abundant perspiration, nj.o|ja{,iy frpij, 



which throws out the excremeutitious fluids, that are so fatal to them their perspira- 



even in the open air, as to render a certain space among their neighbours ti"r^ "ot bein^ 



necessary to their vigorous growth. carried olF, . , 



which 



