An introduction to practical chemistry : including analysis . presentedby the number SECTION gravity of solids heavier than water. 145. When the substance is solid and insoluble inwater, its specific gravity may be ascertained in thefollowing manner. Weigh it first in air, taking care 1 See Fowness Manual of Chemistry, p. * 66 SPECIFIC GRAVITY. to remove any dust or loosely-adheringparticles. Then suspend it by meansof a horsehair, from a hook attached tothe scale-pan, making a small loop atone end of the hair, passing the otherend through it, and inclosing the sub-stance
An introduction to practical chemistry : including analysis . presentedby the number SECTION gravity of solids heavier than water. 145. When the substance is solid and insoluble inwater, its specific gravity may be ascertained in thefollowing manner. Weigh it first in air, taking care 1 See Fowness Manual of Chemistry, p. * 66 SPECIFIC GRAVITY. to remove any dust or loosely-adheringparticles. Then suspend it by meansof a horsehair, from a hook attached tothe scale-pan, making a small loop atone end of the hair, passing the otherend through it, and inclosing the sub-stance in the noose. Thus suspended, itis immersed in water (Fig. 55), and careshould be taken that it is covered on allsides by at least half an inch of bubbles of air frequently adhere tothe surface, and these must be brushedoff with a feather or camel-hair pencil, asthey would tend to buoy it up, andcause the specific gravity to appear results may be noted down as follow : Weightof the substance in air . . = in water . = Loss • . =. which number represents the weight of an equal bulkof water. Then by dividing the weight in air by theloss, or the weight of an equal bulk of water, the speci-fic gravity is ascertained. Weight in air Loss = specific gravity. In this way determine the specific gravity of some ofthe following substances:—marble, amber,iron-pyrites, sulphate of baryta, jet, lead,zinc, glass, and SECTION gravity of solids lighter than water. 146. If the solid be lighter than water,as cork, a slight modification of the aboveprocess is necessary. Weigh the substance first in air; then 1 The following are the specific gravities of these substances, some ofwhich, however, vary considerably. Marble 2-70 ; amber LOS; iron-pyrites 4-90 ; sulphate of baryta L47 ; jet L30; lead 1L35 ; zinc 7*00 ;Hint glass 330; and agate 2-60.
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