[ 594 ]■ 
1 V. 
ExtraSl of a Letter from Win. Brownrigg M. D. 
and F. R. S. to Wm. Watfon F. R. S. contain- 
ing J'ome further Experiments upon the Platina. 
Wbitehaveji , Feb. 13,1750. 
Read Feb. 28. y WAS favour'd with your Letter of 
1 7S°'S 1 ' y <2)ec. if, and am much obliged to you 
for the Trouble you took in prefenting my Speci- 
mens of the Flatina to the Royal Society , together 
with my Memoir relating thereto ; and 1 thank you 
for the Addition you made to it of the Extract of 
Don d' Ulloa’s Voyage. 
The Gentleman, whofe Experiments on Flatina 
I mention'd to the Royal Society , was Mr. Charles 
IVood , who permitted me to make what Ufe of 
them I pleafed ; and I did not pretend to have 
made any new Difcovery, nor to know fo much of 
that Body, as hath long been known to the Spaniards. 
I might indeed have made ufe of his Authority } 
but he was not ambitious of appearing tn Print. 
The chief thing about which I had any Difficulty, 
was what had been aflferted of the Flatina\ refilling 
the Force of Lead in Coppellation. This Experiment 
1 have tried therefore, by adding to gr xxvi. of 
Flatina , fixteen times its Weight ot pure Lead, 
that I had myfelf reduced from Litharge. To the 
Lead put into a Coppel, and-placed n a propei Fur- 
nace j as foon as it was melted I added the Flatina , 
which in a fhorr time was diflfotved in the Lead. 
After the Lead was all wrought off, there remain'd 
at the Bottom of the Coppel a Pellet of Flatina , 
which I found to weigh only gr. xxi. 5 fo that, in 
