On the Idenlihj of Silex and Oxygen. iCg 



philosopher. " Where," says Mr. Ellis, *' is ihere an in- 

 stance, in the whole circle of existence, of a living agent 

 not onlv first forming its own food, but feeding on its own 

 excretions*? 



Few circumstances occur in the oeconomv of vegetables 

 "more inexplicable than the circulation and accumulation 

 in particular receptacles of insoluble salts, and, among others, 

 particularly that of phosphate of lime, which is verv abundant 

 in most kinds of grain, though it is chiefly situated in the 

 seed. Though the last part formed in the whole period of 

 growth, the seed is the proper receptacle for this solid and 

 insoluble compound. How such a salt should pass through 

 the whole circulation to be deposited in the most distant 

 extremity, is truly wond:^rful. It may be said, by way of 

 explanation, that, bv an excess of acid, this salt becomes 

 very soluble, and that vegetables in general contain acids. 

 This position, however, is untenable; for these vegetables, 

 especially oats and wheat, have a great deal of carbonate of 

 lime or chalk in their stems, leaves, and other parts; and as 

 the super-phosphate must pass this way before it can arrive 

 in the grain, it is evident thai this phosphate of lime could 

 not pass with impunity but must be arrested in its progress 

 by the carbonate. 



It is not only in the composition of vegetable bodies, b.it 

 even in the animal organs, silex seems to have been either 

 disresfarded or considered as a mere accidental material. It 

 is true, that it does not occur so copiously as in the vcsre- 

 table constitution, nevertheless it is assuredly necessary to 

 the animal perfection ; and if we appeal to the nature and 

 functions of some animals, we nuist either confess this sub- 

 stance to be quite essential to the life of such animals, or <;ive 

 some more satisfactory reasons for its presence in ih^ir or- 

 gans, and as a ptrt of their system. 



According to modern experiments, the human hair, and, 

 I shoidd suppose, by no very ft)iced analogy, the hair of all 

 animals wliatcvcr, contains silex as a constituent element, 

 'J'his substance may probably enter also into the composition 



* Inquiry, — on vcj^cl'dioii, &c. 



of 



