IN POPULAR PHYSICS. 31 



23. How many oz. of iron will a cubic foot of cork float 

 in water ? 



1,000 oz. = weight of a cubic foot of water. 

 .240 = spec. grav. of cork. 



240 = weight of a cubic foot of cork. 

 1,000 oz. 240 oz. = 760 oz., the buoyant force of a cubic foot. 



24. IVJiat is the specific gravity of a body whose weight 

 in air is 3O grs. and in water 2O grs. <? 



30 grs. 20 grs. 10 grs. 



30 grs. H- 10 grs. = 3. 

 The body is three times as heavy as water. 



25. Which is heavier, a pail of fresh-water or one of 

 salt-water ? 



A pail of salt-water is as much heavier than one of fresh- 

 water as the weight of the salt added to make the brine. 



26. Tlie weights of a piece of syenite-rock in air and in 

 water were 3941.8 <jrs. and 26O7.5 grs. Find its spec, 

 grav. Ans. 2.954. 



27 A specimen of green sapphire from Slam weighed 

 in air 21.45 grs. 9 and in water 16.33 grs. Required its 

 spec. grav. Ans. 4.189. 



28. A specimen of granite weighs in air 534.8 grs., 

 and in water 334.6 grs. Wliat is the spec, grav.? Ans. 

 2.671. 



29. What is the volume of a ton of iron ? 



1,000 oz. = weight of 1 cu. ft. of water 

 7.8 spec. grav. of iron. 



7,800 oz. = weight of a cu. ft. of iron. 

 32,000 oz. (a ton of iron) -*- 7,800 (weight of a cu. ft.) = 4/g- cu. ft. 



