1 70 On the Idenl'ity of Silex o^d Oxygen. 



of o'her anunal covtriagr, such as ^tuies, cjuills, fc-nthers, 

 wool, and a prfdigious va; ely of such usctiil appendages. 

 For the discoxeu of silex in hum ui hair we are. indebted to 

 the iiuiuslry ami sagacitv of M. Vauqueiin ; and from that 

 gentleirian's labours we kavn, that betsides a notaoie portion 

 ()f silex in hair, there are many other ingredients; thus, 

 he shows sulphur, iron, carbon, lime, phosphorus, man- 

 ganese, oxyg^, hvdrogen, and nitrogen, as the associates 

 of silcx in the hair, of winch lie analyzed sevcial specimens*. 

 The munner in which this substance is assimilated and de- 

 poritcd, and whence it originates, are certainly important 

 questions ; for, here silex seems to have pieferrLd the most 

 inaccessible situation of the whole human frame, as if it 

 would shun detection. If ii is, therefore, in the constitution 

 of hair, we must be compelled to admit that it circulates in 

 our fluids ; I believe, however, there is at least one strong 

 objection against this conclusion, which on the present oc- 

 casion It is unnecessary to mention. 



Silex undoubtedly form? a part of our food, hut how it is 

 afterwards disposed of, remaiuo still a secret , ,t also enters 

 into the system as well as into the food of every animal, I 

 believe, with no exception, and there are exa'i'ples, in some 

 animals, where it evidently performs verv important offices. 

 It is worthy of notice that the excrencnts of animals are 

 generally composed with some of this substance as a princi- 

 ple, particularly those of horses and sheep ; and, we oiay 

 farther remark, these secretions are always of an acid nature. 

 It is, possibly, on account of this properly that the dung of 

 pigeons has been found to be an excellent manure for vines, 

 for It contains a large qnantHy of silex. 



The stomachs of animals in general secrete an acid or 

 gastric juice, and the elastic membrane that lines the giz- 

 zard of the domestic fowl -and, indeed, of all 2;ranivorous 

 birds, is so acid that it very effectually coagulates milk. 

 Even when dried and powdered, if this be maieraled in water 

 till the acid is abstracted, the solution will readily turn milk 

 and redden'blue vegetable colours. Here, I should think, 



♦ Ann.de Chimic, Avril, 1806. 



there 



