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.