C 1*8 ] 



commonly made of wood, which ought to be chofen 

 fmooth, hard and compact, wherein are no pores 

 in which the minute grains of the pounded matter 

 may conceal themielves. 



It is to be obferved, that if any fuch matter is 

 to be wafned, which is fufpecled to contain fome 

 native metal, as filver or gold ; a trough mould be 

 procured for this purpofe, of a very Iballow flope, 

 becaufe the minute particles of the native metal 

 have then more power to anemble together at the 

 broad end 3 feparate from the other matter. 





SECT. LXV. 



The management of this trough, or the man- 

 ner of warning, which I fuppofe to be known be- 

 fore, confifts chiefly in this : That when the matter 

 is mixed with about three or four times its quantity 

 of water in the trough, this is kept very looie be- 

 tween two fingers of the left hand, and fome light 

 itrokes given on its broad end with the right, that 

 it may move backwards and forwards, by which 

 means the heavieft particles afTemble at the broad 

 and upper end, from which the lighter ones are to 

 be feparated by inclining the trough and pouring 

 a little water on them. By repeating this procefs, 

 all fuch particles as are of the fame gravity may 

 be collected together, feparate from thofe cf a dif- 

 ferent gravity, provided they all were before equally 

 pounded ; though fuch as are of a clayifh nature, 

 are often very difficult to feparate from the reft, 

 which, however, is of no great confequence to a 

 fkilful and experienced wafher. The wafhing pro- 

 cefs is very neceffary, as there are often rich ores, 

 and even native metals, found concealed in earths 

 and fand in fo minute particles, as. not to be dis- 

 covered by any other means. 



FINIS, 



