45, CORNHILL, B.C., AND 122, REGENT STBEET, W., LONDON. 



191 



DIRECTIONS FOR USING NICHOLSON'S GRAVIMETER. 



534 To find the specific gravity of a mineral or other solid, place weights in the upper cup 

 sufficient to sink the Hydrometer to the mark on the stem when the Hydrometer is floated in 

 distilled water, and call this weight A. Now take a piece of mineral of less weight than A ; 

 place this in the upper cup, and add weights until the Hydrometer sinks to the same mark 

 as before. Call the weights added B. Remove the solid from the upper cup to the lower, 

 allowing the weights to remain in the upper cup. Add weights until the Hydrometer sinks 

 to the mark on the stem, and call the additional weights C. Subtract B from A, and divide 

 the remainder by C, and the quotient is the specific gravity. 



Thus, suppose the specific gravity of a specimen of fluor-spar is required. First, on 

 trial, we find that 460 grains placed in the upper cup will sink the Hydrometer to the mark 

 on the stem when floated in distilled water consequently, A is equal to 460 grains ; and 

 that when the fluor-spar is placed in the upper cup, 92 grains must be added to sink the 

 Hydrometer to the same level as before then B is equal to 92 grains. Now, on removing 

 the fluor-spar to the lower cup, 115 grains must be added to the 92 grains still remaining in 

 the upper cup to sink the Hydrometer to the same mark as before ; therefore C is equal to 

 115 grains. Then 



460 

 92 



115)368(3-2 

 345 

 230 

 230 



Censequently, 3-2 is the specific gravity required. 



In our Chemical Section will be found and described Balances arranged to 

 exhibit the same facts with extreme precision. 



URINOMETERS. 



535 



536 

 537 



538 



539 



540 

 541 



FIG. 539. 



FIG. 538. 



Urinometer, for ascertaining the Specific Gravity of Urine, of two 



forms, figs. 444 and 444* 



Ditto, ditto, in round leather pull-off case, with graduated test glass 



Ditto ditto, in hingedj.eatb.er case 



Ditto ditto, with test glass and thermometer, 



Ditto, ditto, in hinged Leather case, fitted up with thermometer, 



spirit lamp, acid bottle, test tubes, dropping tube, graduated 



jar, test papers, &c. (fig. 538) 



Urinometer, larger case, and more complete, with extra stoppered 

 and cut test bottles and evaporating dishes, tube holder, &c. 



(fig. 539) 2 



Metal Urinometer, Gilt or Plated, in pull-off case . 



Urinometer Test Papers, various per book 



s. a. 



2 



15 







1 10 



