On Extensions of the Dialytic Method of Elimination. 221 



not to others ; Saussure found that a plant of Lythrum Salicaria 

 flourished for five weeks in an atmosphere of this gas. Is it not 

 possible that some of the compound gases which frequently con- 

 taminate hydrogen^ and which are known to be poisonous even 

 in very small proportion, may have led to the destruction of those 

 plants which died apparently through the influence of hydrogen 

 gas ? As far as our own experiments are concerned, we find 

 hydrogen, nitrogen, oxygen, carbonic oxide, nitrous oxide, and 

 perhaps gaseous hydrocarbons, to be perfectly innocuous to vege- 

 table life in any proportion. 



The earth^s atmosphere is common to all the tribes of organized 

 existence which inhabit the land, whether fixed to one locality or 

 endowed with voluntary motion ; but its component gases per- 

 form different functions in respect to the two great classes into 

 which we are in the habit of dividing them. No animal, as far 

 as we are aware, can exist for any length of time in an atmosphere 

 devoid of oxygen, whilst on the other hand all those which are 

 usually included under the appellation of the " vegetable king- 

 dom '' are dependent for their food upon those gases which con- 

 tain carbon. We know from Regnault^s experiments that the 

 amount of oxygen in the air may vary largely, and that the 

 nitrogen may be replaced by hydrogen gas without any marked 

 effect upon animal life ; and we now find even more strikingly 

 in regard to plants, that either of the great constituents of the 

 atmosphere may prevail to the exclusion of the other, or that 

 they may be replaced by totally difi*erent gases, without involving 

 the destruction of the living organism ; of course they cannot 

 increase in substance without carbonaceous food, yet the depriva- 

 tion of this appears only to lead to an indefinite suspension of 

 their functions. Doubtless the actual constitution of the atmo- 

 sphere is that which is most suited to the permanent well-being 

 of the whole of the organized creation, and perhaps it is equally 

 requisite both for plants and animals ; yet it is evident that great 

 deviations from its normal constitution may take place without 

 producing serious injury. 



XXXIII. On Extensions of the Dialytic Method of Elimination. 

 By J. J. Sylvester, M.A., F.i?.>Sf.* 



THE theory about to be described is a natural extension of 

 the method of elimination presented by me ten years ago 

 (in June 1841) in the pages of this Magazine, which I have been 

 induced to review in consequence of the flattering interest recently 

 expressed in the subject by my friend M. Terquem, and some 



* Communicated by the Author. 



