French National Injlitute.. ' 379 



purpofe by Drcbell and Halley. After having calculated, 

 hour bv hour, the conrumplion of the refpirable part of the 

 air, and the formation of carbonic acid gas, he indicates the 

 chcniiciil means for ameliorating what remains ot the former, 

 and of abforbing the latter; an'd, in the laft place, of pre- 

 venting tlie danger arifmg from accimiulated animal emana- 

 tions, bv the momenlaneous opening a bottle of oxygenated 

 nniriatic acid, whicli appears to him very proper to be iub- 

 ftituted in the place of the litjuor mentioned by Boylc as 

 having ferved to cool the air in a veflel rowed under water. 



I'HILOSOPHV OF VEGETABLES. 



On the Injlucnce ivh'ich the AW and other aer'iforvi Fluids 

 ha-ve en Germination. 



This new labour of Senncbier is a fupplemcnt to his large 

 work on the phyfiology of vegetables. The experiments were 

 made bv placing the feeds on moid llanncl, under bells filled 

 with dificrent kinds of gas, the influence of which it was in- 

 tended to trv. All thete i'ecds refufed to germinate in azote, 

 in carbonic acid, and in pure hydrogen gas. The prefence 

 of oxyaen was in general ncceli'ary, and its employmenL is 

 in part to abforb the carbon of the feeds, to form of it car- 

 bonic acid. What is fmgular is, that pure oxygen is not the 

 gas moll favourable to germination; it accelerates germina- 

 tion, but it weakens it. " The action of oxygen mult be me- 

 liorated bv the prefence of a fubftance ina(S;ive by itfelf; and 

 we here find that wonderful fart prclented to us by fo many- 

 other circumltances of the organic economy, viz. that the 

 mixture moll: favourable to germination is that of which the 

 atuiofphere is formed, that is, about three-fourths of azote 

 to a fourth of oxygen; and germination docs not lake place 

 at all if there is not an eigluh of oxygen at lead in the at- 

 niofpliere. 



But the manner in which oxygen is introduced into this 

 atmofpbere is not a matter of indiflerenec ; it nu\U be poured 

 into it fuddenly. Were it made to enter only little by little, 

 the lirlt portions would fcarccly be lunicient lo abforb the 

 carbon of the feeds, and no more would remain to vivify 

 them. 



S(.eds may be niade to germinate alfo, by mixing oxygen 

 with carbonic acid, or \\\i\\ hydrogen. In the huu-r cafe, 

 the ciirl)on which ilfucs from liie^'fet^ds rmites itfelf inti- 

 niatclv v.ith the liydrogen. 'I'oo much carbonic acid in air 

 does more hurt lo IccdiTlhan too iiutch azote, and too nuich 

 a/ole more than too much hydrogen. Various vapours may 

 alio nl'AT the air, lo as to annihilate germination: ot this 



S 4 - kind 



