TABLE OF SPECIFIC GRAVITIES. 



209 



A knowledge of the specific gravities of various sub- 

 stances becomes useful in many ways, among which is 

 ascertaining the weight of any structure, machine, or im- 

 plement, by knowing that of the material used in its man- 

 ufacture ; determining the cost, by the pound, of such 

 material ; or knowing the bulk or size of any load for a 

 team. The latter may often be of great use in ordinary 

 practice, by enabling the teamster to calculate beforehand 

 the amount of load to give his horses, whether in timber, 

 plank, brick, lime, sand, or iron, without first subjecting 

 them to overstraining exertions in consequence of error in 

 random guessing. 



Tables of specific gravities, for this purpose, and weights 

 of a cubic foot of different substances, are here given. 



TABLE OF SPECIFIC GRAVITIES. 



Mdals. 



Gold, pure 19.36 



" standard 17.16 



Mercury 13.58 



Lead 11.35 



Silver. 10.50 



Copper 8.83 



Iron 7.78 



" cast 7.20 



Steel 7.82 



Brass, common 7.82 



Tin 7.29 



Zinc 6.86 



Stones and Earilis. 



Brick 1.90 



Chalk 2.25 to 2.66 



Clay 1.93 



Coal, anthracite, about 1.53 



Coal, bituminous 1.27 



Charcoal 44 



Earth, loose, about 1.50 



Flint 2.58 



Granite, about 2.65 



Gypsum 1.87 to 2.17 



Limestone 2.38 to 3.17 



Lime, quick 80 



Marble 2.56 to 2.69 



Peat 60 to 1.33 



Salt, common 2.13 



Sand 1.80 



Slate 2.67 



Woods dry. 



Green wood often loses one-third of its weight by seasoning, and 

 sometimes more. The same kind varies in compactness with soil, 

 growth, exposure, and age of the trees. 



