The specific gravity of a substance is the number of times it is heavier than the weight of an equal bulk of water. It may be expressed thus:

 Specific gravity (sp. gr.) = Weight of body or substance Weight of an equal bulk of water

The specific gravity of a solid is obtained by first weighing or computing the weight of the object. The weight of an equal bulk of water is then computed. Finally, the weight of the object is divided by the weight of the equal bulk of water.

The following tables show the weights and specific gravities of the most important metals and liquids.

Weight and Specific Gravity of Metals

 Metals W. per Cu. Ft., Lbs. W. per Cu. In., Lbs. Specific Gravity Aluminum.............................. 166 .096 2.67 Antimony, cast........................ 419 .242 6.72 Bismuth.............................. 613 .353 9.822 Brass, Cast............................ 524 .3 8.4 Bronze............................... 534 .308 8.561 Copper, cast............................ 537 .31 8.607 Copper, wire.......................... 555 .32 8.9 Gold, 24 carat......................... 1208 .697 19.361 Cold, standard......................... 1106 .638 17.724 Gun-metal............................ 528 .304 8.459

Weight and Specific Gravity of Metals - (Continued)

 Metals W. per Cu. Ft., Lbs. W. per Cu. In., Lbs. Specific Gravity Iron, cast................. 450 .26 7.21 Iron, wrought.............. 485 .28 7.78 Lead, cast................. 708 .408 11.36 Lead, rolled............... 711 .41 11.41 Mercury.................. 849 .489 13.596 Platinum.................. 1344 .775 21.531 Platinum, sheet............ 1436 .828 23. Silver, pure................ 654 .377 10.474 Silver, standard............ 644 .371 10.312 Steel...................... 490 .284 7.85 Tin, cast.................. 455 .262 7.291 Zinc...................... 437 .252 7.

Weight and Specific Gravity of Liquids

 Liquids Specific Gravity W. per Cu. In., Lbs. W. per Gal., Lbs. Water, distilled, 60° F...... 1. .036 8.33 Water, sea................ 1.03 .037 8.55 Water, Dead Sea........... 1.24 .045 10.4 Acid, Acetic............... 1.062 .038 8.78 Acid, Nitric............... 1.217 .044 10.16 Acid, Sulphuric............ 1.841 .067 15.48 Acid, Muriatic............. 1.2 .043 9.93 Alcohol, pure.............. .792 .029 6.7 Alcohol, proof............. .916 .033 7.62 Alcohol, of commerce....... .833 .030 6.93 Cider..................... 1.018 .036 8.4 Honey.................... 1.45 .052 12.

Weight and Specific Gravity of Liquids - (Continued)

 Liquids Specific Gravity W. per Cu. In., Lbs. W. per. Gal., Lbs. Milk..................... 1.032 .037 8.55 Molasses.................. 1.426 .05 11.66 Oil, Linseed............... .940 .034 7.85 Oil, Olive................. .915 .033 7.62 Oil, Turpentine............ .870 .031 7.16 Oil, Whale................ .923 .033 7.65 Naphtha.................. .848 .031 7. Petroleum.,............... .878 .032 7.39 Tar...................... 1.015 .036 8.4

Water. - The weight of fresh water is in practice usually assumed as 62 1/2 lbs. per cubic foot. But 62 1/4 would be nearer the truth at ordinary temperatures, about 70°; or 1 lb. = 27.759 cu. in.