On the Identity of Silex and Oxygen. 167 



rendering this materia! either soluble ormiscible, and, hence, 

 it is more difficult to accoimt for its presence in the vege- 

 table system, than tor thai of any other soHd body. 



T am strongly induced to establish this as a general maxim, 

 that wherever potash is collected or, shall we say, generated 

 in the vegetable structure, there, by necessity, there must 

 also be silex. All the potash of commerce contains si- 

 lex, and, in whatever uav it is purified, it is difficult to 

 divest It completely of this substance ; for, unless it be su- 

 per-saturated by carbonic acid, or some other scientific mode 

 pursued to purifv it, potash never quits entirely this sub- 

 stance. This being the true situation of all native potash 

 without exception, from whatever source it is derived, and 

 oxygen being one of the essential principles of potash, T would 

 say, the fair induction from such premises is this ; that the in- 

 variable proximity of silex and potash renders it extremely 

 probable, if not certain, that one is subservient to the forma- 

 tion of the other ; and that silex being avowedly an inde- 

 composable element, it is more reasonable to say that potash 

 is generated from this same element, than to support tlie 

 converse of the argument. Indeed this singular and uniform 

 association can, I thinlc, scarcely l)e overlooked ; it seems 

 to point directly to the source from whence the alkali ob- 

 tains that constituent in its nature, the oxygen or modified 

 silex, especially when it is allowed, that the same connexion 

 occurs in all primordial matter whatever. 



Both ancient and modern expermients prove, that by 

 means of water as the only nourishment, with free admission 

 6f solar light and heat, and exposure to the atmosphere, ve- 

 getables may be cultivated even from germination to perfect 

 maturity, and that they produce, bv analysis, precisely the same 

 materials peculiar to each individual plant. It is a common 

 practice, I know, particularly on board our East Indiamen, 

 to cultivate various kinds of herbs for salad, by sowing the 

 ?eeds upon a piece of woollen cloth or contmon flannel j 

 where, by no other means than pure water and exposure to 

 the atmospheric influence, the vegetation succeeds, and in 

 this way these herbs arc supplied by succession during the 

 whole voyage. 



L4 In 



