184 SPECIFIC GRAVITY. 



RULE. Attach to it a piece of metal sufficient to sink it 

 in the water ; weigh the piece added and the body separately, 

 both in and out of the water, and find how much each loses 

 in water by subtracting its weight in water from its weight 

 in air, and subtract the less of these differences from the 

 greater ; then as the remainder is to the weight of the 

 light body in air, so is 1000 to the specific gravity of the 

 body. 



EXAMPLE. Required the specific gravity of a piece of 

 wood which weighs 20 Ibs. in air ; attached to it is a piece 

 of metal, which weighs 30 Ibs. in air and 25 Ibs. in water, 

 and the two pieces together weighing in water 10 Ibs. ? 



SOLUTION. 20 4- 30 1 = 40 

 30-25= 5 



35 : 20:: 1000 : 571.44. Ans. 



To reduce the specific gravity of a body to its weight in 

 Ibs. per cubic foot. 



RULE. Divide the specific gravity by 16, and the quotient 

 is the weight of a cubic foot in Ibs. 



EXAMPLE. Required the weight of a cubic foot of a sub- 

 stance the specific gravity of which is 4.800 ? 



SOLUTION. 4.800-i-16=300 Ibs. Ans. 



