(489 ) 
Water than in the Air, by the weight of as much Water 
as is equal to it in Bulk. The difference then of the 
Weights in Air and Water, gives the weight of fo much 
Water, and dividing the greater number by the leffer, 
the Quotient compar'd to unity, will be the proportion 
of the Weights of the folid Body and Water. 
Rock^Cryfial, and the lacks of Vaults are us'd as the 
Standard, ("being the moft homogeneous and fimple ) 
to compare other Stony Bodies with^ which if found 
heavier are prefum'd to contain matter heavier in [peck. 
They are to water as 2 f to i, Lapis Hematites almoft 
double to the Standard,and Iron is difcover'd in it by the 
Styptical tafte of its Flowers, and by the black colour 
when mixt with Galls. Lapis Lazuli having a vomitive 
Quality as j to i. Loadjione more than 4 to 1, Lap. Ca- 
laminaris, us'd in the turning Copper into Brafs, and of 
a Quality very reftringent, appears to weigh as almoft 
£ to i. Coral, truly therefore efteem'd a Ltthodendron 
foroewhat exceeds Crystal. Pearl near the weight of Cry- 
jial. Calculi Humani and Bezoars (Animal Concretions) 
amount not to twice the weight of Water, and are by 
a fifth part lighter than Cryftal, by which counterfeit 
zoars are dete&ed : fuch an one being found as heavy as 
a mineral. It is further obferved that counterfeited/ 
Eyes are of much more weight than natural. Falfe 
Stones are eafily dete&ed, the Mineral which gives the 
Colour making them preponderate to true Gems. Falfe 
Coyns in this manner are eafily difcoverable. 
Our Author having in thefe particulars (hewn in what 
manner all folid Bodies heavier than Water may be com- 
par'd to one another, and not only their Specific Gravity^ 
but their qualities very often dete&ed, comes now to 
confider and propofe, 1 . How Bodies lighter than Water 
may be exanrin'd in it, viz. by adding Lead to Wax 
or Fir-wood, and fubdudting for tbs heavy Body fo 
added. 2. How Fluids, as Mercury, or Chymical Oyls of 
CIoves.,d^.or Bodies diffoluble in Watery Sublimate, Alum* 
Vitriol, 
