Page images
PDF
EPUB

Of Specific Gravities.

EXAMPLES.

1. A piece of elm weighs 15 lbs. in open air. A piece of copper which weighs 18 lbs. in air and 16 in water is attached to it, and the compound weighs 6 lbs. in water : what is the specific gravity of the elm? Copper.

Compound. 18 in air.

33 in air.

16 in water.

6 in water.

2 loss.

27 loss.

Then, 27-2=25 =difference of losses.

Then, as 25 : 15 : : 1000 : 600, which is the specific gravity of the elm.

2. A piece of cork weighs 20 lbs. in air, and a piece of granite weighs 120 lbs. in air, and 80 lbs. in water. When the granite is attached to the cork the compound mass weighs 16 lbs. in water : what is the specific gravity of the cork ?

Ans. 240.

PROBLEM III.

To find the specific gravity of fluids.

RULE.

1st. Weigh any body whose specific gravity is known,

both in the open air, and in the fluid, and take the difference, which is the loss of weight.

Of Specific Gravities.

2d. Then say, as the true weight is to the loss of weight,

so is the specific gravity of the solid, to the specific gravity of the fluid.

EXAMPLES.

1. A piece of iron weighs 298,1 ounces in the air, and 259,1 ounces in a fluid, the specific gravity of the iron is 7645: what is the specific gravity of the fluid ? First, 298,1 - 259,1=39 loss of weight : Then, 298,1 : 39 : : 7645 : 1000, which is the specific gravity of the fluid: hence the fluid is water.

2. A piece of lignumvitæ weighs 424 ounces in a fluid, and 1663 ounces out of it; what is the specific gravity of the fluid—that of lignumvitæ being 1333 ?

Ans. 991, which shows the fluid to be liquid turpentine or Burgundy wine.

Note.--In a similar manner the specific gravities of all liquids may be found from the following table.

[merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small]

Of Specfiic Gravities.

[ocr errors]

Spec. grav. wt. cub. ft.

Spec. grav. wt. cub. ft. White glass 2892 lbs. Cork

240 15:00 Pebble

2664
166:50 Poplar

383 23.94 Slate 2672 167.00 Larch

544 34:00 Pearl 2684 Elm and West

556 34.75 Alabaster 2730

India fir Marble

2742 171.38 Mahogany 560 35-00 Chalk 2784 174.00 Cedar

596 37.25 Limestone 3179 193•68 Pitch pine

660 41.25 Wax

897
Pear tree

661 41:31 Tallow

945
Walnut

671 41.94 Camphor

989
Elder tree

695 43:44 Beeswax

965
Beech

696 43:50 Honey 1456

Cherry tree 715 44.68 Bone of an ox 1659

Maple and Riga fir 750 46.87 Ivory 1822

Ash & Dantzic oak 1760 47:50 Air at the

793
Apple tree
14

49:56 earth's surface

Alder

800 50.00 Liquid turpentine 991

Oak, Canadian 872 54:50 Olive oil

915

Box, French 912 57.00 Burgundy wine 991

Logwood

913 57:06 Distilled water 1000

Oak, English 970 51.87 Sea water 1028

Oak, 60 years old 1170 73:12 Milk 1030 Ebony

1331

83:18 Beer 1034

Lignumvitae 1333 83-31

REMARK.-In the table of specific gravities, the cubic foot of water, which weighs 1000 ounces, is taken as the standard, and the figures in the column of specific gravity shows the weight of a cubic foot in ounces, or how many times each substance is heavier or lighter than water. The other column shows the weight in ounces of a cubic inch, or the weight in pounds of a cubic foot.

PROBLEM IV

The specific gravity and weight of a body being given, to find its solidity.

Of Specific Gravities.

RULE.

As the tabular specific gravity of the body is to its

weight in ounces avoirdupois, so is 1 cubic foot, to the content in cubic feet.

EXAMPLES.

1. What is the solid content of a block of marble, that weighs 10 tons, its specific gravity being 2742. First, 10 tons=358400 ounces. Then, 2742 : 358400 :: 1:130 13:341, which is the content in cubic feet?

NOTE.-If the answer is to be found in cubic inches, multiply the ounces by 1728.

2. How many cubic inches in an irregular block of marble, which weighs 112 pounds, allowing its specific gravity to be 2520 ?

3. How many cubic inches of gunpowder are there in 1 pound veight, its specific gravity being 1745 ?

Ans. 154, nearly. 4. How many cubic feet are there in a ton weight, of dry oak, its specific gravity being 925.

Ans. 3813

THE END.

« PreviousContinue »