These things being noticed, in relation to metals, and semi-metals in general, I will now proceed to relate a few curious cases, in respect of the metals.
*Gold, our first metal, has ten sensible criterions. It is the heaviest and densest of all bodies: the most simple of all bodies: the most fixed of all bodies: the only body that cannot be turned into scoriae, by antimony and lead; the most ductile of all bodies: so soft as to be scarcely elastic or sonorous: must be red hot to melt: is dissolvable by sea-salt and its preparations, but remains untouched by any other species of salts; and of consequence not liable to rust; as aqua regia and spirit of sea-salt do not float in the air, unless in laboratories; or chemists shops, where we find them sometimes: It unites spontaneously with pure quick-silver: It never wastes by emitting effluvia, or exhalations. These are the ten sensible properties or characteristics of this metal. It is certainly pure gold, if it has these criterions, and they are of great use in life; especially to persons who have to do with that subtil tribe, the alchemists.
As to the weight of gold, it is more than nineteen times heavier than water, bulk for bulk, and this property is inseparable from it; it being impossible to render gold more

or less heavy; and for this reason, the specific gravity of gold, if it had no other criterion, might demonstrate real gold. To make gold, other metals must be rendered equiponderant to it: And therefore, if an alchemist should offer to obtrude a metal on you for gold, hang an equal weight of pure, and of suspected gold by two threads to a nice ballance, and on immerging them in water, if the alchemist's gold be pure, the water will retain both pieces in oequilibrio; otherwise, the adulterate metal will rise, and the pure descend.
The reason is, all bodies lose some of their weight in a fluid, and the weight which a body loses in a fluid, is to its whole weight, as the specific gravity of the fluid is to that of the body. The specific gravity of a body is the weight of it, when the bulk is given; 38 grains of gold weighed in the air, is not the true weight of it: for there it loses the weight of an equal bulk of air: It weighs only 36 grains in the water, and there it loses the weight of as much water, as is equal