.1- 



•^6 Dy. Wall on the Origin if the 



cheiTOfl of no mean reputation, who may al fo, 

 without much impropiiety, be confidered as a 

 modern writer, his DilTertation on Salt Petre 

 being publifhed fo lately as the year 1732. This 

 doftrine, concerning nitre, cannot therefore be 

 confidered as antique, and on that account, re- 

 jedUd as weak and groundlefs. — Yet later obfer- 

 vations have fully fliewn, that this theory has 

 been formerly too flrongly infifted upon. Au- 

 thentic accounts of the mode of collecling nitre 

 in the cafl:, very coirefpondent with that alluded 

 to above, have been fince received from China, 

 and the coafl: of Coromandel, which are cited by 

 Dr. WatJoHy * and prove at leafl: (though more 

 difputable inferences may have been drawn from 

 them) that nitre may be formed without the 

 affjftance of art, or at lead, without the addi- 

 tion of a vegetable alkali, or wood-a(hes. The 

 account given by Mr. BoioleSi^ of the manner 

 in which nitre is colleded in Spain, flrongly 

 confirms this afTcrtion. In both thefe inftances, 

 perfect nitre is obtained from the fuperficial 

 mould of the foil, only previoufly ploughed, and 

 piled up in heaps. This mould or furface of the 

 earth is formed in fituations, like thofe above 

 alluded to, remote from the habitations and 

 refidence of men or cattle, entirely fronri the 



* Watfons Effays, Vol. I. p. 307. 

 f Dillon^ Tranllatioa of Don Boz{<Iej's Travels in Spain, 

 p. ^2. 



^ decayed 



