HYDRAULICS AND HYDROSTATICS. 



Fig. 327. 



Scaled and Weights. Small scales and weights (Fig. 23*7) 

 used for weighing in chemical experiments, packed in a 

 small case ; the weights ranging from half a grain to a quarter 

 of an ounce. Price, - $1.25 ; fine quality, $2.50. 



" larger scales, with stand, on mahogany 

 box, with weights, &c. - $10.00 



The Hydrometer. (Fig. 238, next page.) Hydrometers 

 are instruments used by dealers in wines, spirits, acids, 

 alkalies, syrups, and all commercial liquids, for ascertaining 

 their comparative strength. 



This instrument, as represented in the figure, consists of a 

 hollow glass ball, B, with a smaller ball, C, appended to it, 

 and which, from its superior weight, serves to keep the in- 

 strument in a vertical position, to whatever depth it may be 

 immersed in a liquid. From the large ball rises a cylindrical 

 stem, a d, on which are marked divisions into equal parts ; 

 and the depth to which the stem will sink in water, or any 

 other liquid fixed on as the standard of specific gravity, being 

 known, the depth to which it sinks in a liquid whose specific 

 gravity is required, will indicate, by the scale, how much 

 greater or less it is than that of the standard liquid. 



Those most celebrated, are the scales of Baume, Cartier, 

 Twaddell, and Guy Lussac. Most of these scales are arbi- 

 trary, and formed after the ideas of their projectors, but hav- 

 ing no particular reference by which they may be understood. 



