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true account, of the conducing power, of the dif- 
ferent kinds of metal. 
Having lately been prefented, in the mod 
polite manner, by the celebrated Dr. lew- 
js, f. r.s. See. with fix fpecimens of his pla- 
tina ; in as many different dates : I feledied the 
larged grains, from one of the parcels which 
Dr. lewis informed me had been repeatedly ex- 
pofed to long-continued vehement fires; the mod 
intenfe which he had been able to excite, or 
any veffels he could procure would fupport : and 
after a few fmall globules (confiding doubtlefs in 
great part of heterogeneous metal) had melted out, 
repetitions of the operation produced no further 
^change. It was afterward boiled fucceflively in 
©il of vitriol, aqua-fortis, and fpirit of fait, in 
order to its further purification; and which in- 
deed reduced it to a date the mod pure of any that 
excellent chemid had been able to produce. Having 
ruled a line with a blunt-ended wire, over the fur- 
face of a plate of white wax ; 
EXPERIMENT VII. 
I prefied in the grains of platina lightly, and in 
contact with each other; fo as to form a regular 
line, half an inch long. At each end of the line 
c \ platina, and in contact with it, i placed a thick 
wire, with its ends nicely rounded off, and made 
perfectly fmooth. I covered the platina with a 
piece of thick plate-glafs ; and then difeharged 
through it, three jars containing fix teen 10 u are 
feet of coated furface : when 1 obtained many 
beautiful fpherules of the platina. Several of them 
duck to the wax, and glafs ; and others imperfectly 
formed , upon the edges, See. of the grains: which 
