Specific Gravity

—The weight of a given substance relatively to an equal bulk of some other substance which is taken as a standard of comparison. Water is the standard for liquids and solids, air or hydrogen for gases Ifa certain ma be weighed first in air then in water, and the weight in air divided by the lo of weight in water, the result will give the specific gravity; thus, taking a ten ound piece of cast iron, its weight, suspended rom the scale-pan in a bucket of water, will be 8.6 lbs., dividing 10 by the difference 10—8.6 or 1.4, the answer will be 7.14, which is the specific gravity of cast iron.