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Specific Gravity of Liquids

By the Balance.

In ordinary language the terms density and specific gravity (s. g.) are used to represent the relative weights of equal bulks or volumes of different substances. In order to compare these conveniently, pure water at 60° is taken as the standard. A cubic foot of water weighs 1000 oz., hence to determine the weight of a given bulk of any body the specific gravity of which is known, multiply the cubic content in feet by 1000, and this by the s. g., and the product will be the weight in ounces avoirdupois. Thus, the s. g. of cast-iron is 7.207, that is, it is 7.207 times heavier than an equal bulk of water. A cylinder of cast-iron 1.836. s. g. of the alcohol. Take a bit of glass rod, note its loss when weighed in water and in the liquid under trial. Divide the latter by the former, the quotient will be the s. g. of the liquid. Thus a glass rod loses in water 171 grs., in alcohol, 143 grs. 143-171- Specific Gravity bottles.

These are made to hold 100 or 1000 grs. of pure water at 60°, and are accompanied by a counterpoise. It is only necessary to fill the bottle with the liquid to be tested. Counterpoise and weigh; the weight in grains will be the S. g. Oily and matter should never be introduced into the s. g. bottle. In case the s. g. bottle is not at hand any light flask will do. Make a file mark on the neck, counterpoise it, fill to the mark with pure water at 60°, note the weight of the water.

Empty, dry thoroughly and fill with the liquid to be tested; the weight of this divided by that of the waters. g.

Hydrometers Are instruments for determining the specific gravity of liquids by noting the depth to which a stem sinks. They consist of a cylinder with a weight beneath it to make it float upright, and a graduated stem. When intended for liquids lighter than water, the 0 or point at which they float in pure water at 60° is at the lower point of the stem, and as the iiquid is lighter they sink more deeply; for liquids heavier than water the 0 is at the top of the scale. Many are graduated according to their proposed use, as alcoholometers, lactometers, saccharometers. (See DISTILLATION). The graduation most empoyed is that of Beaumé. Excellent hydrometers with the degrees and the true s. g. on the same stem are made by Dr. W. H. Pile of Philadelphia. To Convert Degrees Beaumé into Specific Gravity. 1. For liquids heavier than water-Subtract the degree B. from 145, and divide into 145, the quotient is the s. g. 2. For liquids lighter than water-Add the degree B. to 130, and divide it into 140. The quotient is the s. g. To Convert Specific Gravity into Degrees Beaumé. 1. For liquids heavier than water. - Divide the B. g. into 145, and subtract from 145. The remainder is the degree B. 2. For liquids lighter than water. Divide the s. g. into 140 and subtract 130 from the quotient.

The remainder will be the degree B.

Table of Specific Gravity.

Mercury Lead Copper Cast Brass Steel Wrought Iron..

Cast Iron....

Tin Marble Common Stone Brick .....

Soil......

Coal, an hracite... bituminous.

Sea-water. 66 Sand ... 13,600 11,325 ...... 9,000 8,000 .. 7,850 .. 7,780 ... 7,207 .................. ... 7,300 2,690 2,520 .... 1,000 @ 2,000 ... 1,974 ....1,436 @ 1,640 1,270 1,520 .. 1,030 1,000 925 ..... 800 755 .. 600 660