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than the other , 'twill juftifie the fufpition i Since as Gold » 
being the heavieft of Metals, cannot be allay 'd by any other 
that will not deprefs our Inftrumenc lefs than Gold can do; 
fo Tinn, being thelighteft of Metals, cannot be mixed with 
any other that will not fink it lower than uninixt Tinn, (fUli 
fuppofing the weights to be the Tame in the Air.j 
And as for the Buyers of Pewter, 'twill be eafie for them 
( if they think it worth while J to find by our Inflrmiient, if 
there be too much or but enough of Lead mixt with the Tinn 
inanaffign'd portion of Pewter of a convenient weight to be 
examined by it. For, having once obferved , how much 
thelnftrument is depreft by a piece of two, three, or four 
Drams, or even an Ounce weight of Pewter, which is knos^n 
to be good , and to contain fuch a proportion of Lead in re- 
ference to the Tinn , if you load the Inftrument with an equal- 
ly heavy piece of any other mafs of Pewter propounded , if 
the Inftrument fink deeper, 'twill be a fign ^ that the former 
proportion of Lead may be very frohahly argued to exceed in 
the mixture I fay, probably ^ becaufe perhaps 'tis poflible to 
cmbafe Pewter by mixing not only Lead but other Mineral 
Subftances , whofe fpecific gravity is not well known : But 
yet I_ fay very probably , becaufe the addition of too much 
Lead is the moft gainful way of adulterating Pewter. And 
the other things that fome imploy, as Regulus of Antimotiy^ 
lim-gkfs^ Coffer ^nd Spelfar , are feldom ufed in great quan- 
tities; and if I thought it worth the while, I could fa- 
cilitate the Difcovery even of thefe by adding, what I have 
obferved of their differing fpecific Gravities, and fome other 
things that I think fitter to be here omitted than to have time 
and words fpent upon them* 
The 
