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Of the specific Gravities of Bodiesi

How to findout the quan-tity of adul-teration inmetals.

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How to tryspirituous li-quors.

Take away the decimal point from the numbers in the right hartd column,or (which is the fame) multiply them by iooo, and they will shew howmany ounces avoirdupoife are contained in a cubic foot of each body.

The use of the table of fpecisic gravities will best appear by an ex-ample. Suppofe a body to be compounded of gold and silver, and itis required to find the quantity of each metal in the eompound.

First find the fpecisic gravity of the compound, by weighing it inair and in water, and dividing its aerial weight by .what it loses thereofin water, the quotient will shew its specific gravity, or how manytimes it is heavier than its bnlk of water. Then, fubtract the specificgravity of silver (found in the table) from that of the compound; and'the specific gravity of the compound from that of gold; the first re-mainder fhews the bulk of gold,, and the latter the bulk of silver, inthe whole compound: and if thefe remainders be multiplied by therespective specific gravities, the products will shew the proportion ofweights of each metal in the body. Example.

Suppofe the specific gravity of the compounded body be 13 5 thatof standard silver (by the table) is 10.5, and that of gold 19.63 :therefore 10.5 from 13, remains 2.5, the proportional bulk of thegold 3 and 13 from 19.63, remains 6.63, the proportional bulk ofsilver in the compound. Then, the first remainder 2.5, multiplied by19.63, the specific gravity of gold, produces 49.075 for the propor-tional weight of gold; and the last remainder 6.6-3 multiplied by 10.5,the specific gravity of silver, produces 69.615 for the proportionalweight of silver in the whole body. : So that, for every 49.07 ouncesor pounds of gold, there are 69.6 pounds or ounces of silver in the body.

Hence it is eafy to know whether any fufpected metal be genuine,or allayed, or counterfeit; by sinding how much it is heavier than itsbulk of water, and comparing the fame with the table: if theyagree, the metal is good; if they differ, it is allayed or counterfeited.

A cubiealinch of good brandy, rum, or other proof spirits, weighs235.7 grains; therefore, if a true inch cube of any metal weighs 235.7grains lefs in spirits than in air, it fhews the spirits are proof. If itloses lefs of its aerial weight in spirits, they are above proci’; if it losesmore, they are under. For, the better the spirits are, they are thelighter; and the worse, <; the heavier. All! hodies. expand with heat andcontract with cold, but forne more and forne lefs than others. 'Andtherefore the specific gravities of hodies are net precifely the fame in *summer as in winter. Jt has- been found, that a cubic inch of goodbrandy is -10 efrains heavier in winter than in’ summer; as muehjspiritof nitre, 2 q gj'a;ns:;._vihegar'6.graiDv anes spring. .water 3. Hence it2 «... is