394 ^' Nicholforis Defcription of anew Injlrument 



of the fluid beyond the expanfion of the glafs 

 veflcl, fo our inftrument will fall by the excefs 

 of the fame expanfion, beyond the proper ex- 

 panfion of the materials it is compofed of. 



To meafure the Jffcific gravities of solid 

 BODIES, The foiid bodies, to be tried by this 

 inftrument muft not exceed looo grains in 

 weight. Place the inftrument in diftiUed water, 

 and load the upper fcale or difti, till the furface 

 of the water interfeds the middle of the ftem. 

 If the weights required to affeCt this be exadly 

 looo grams, the temperature of the water 

 anfwers to 60*^ of Fahrenheit's fcale; if they be 

 more or lefs than icoo grains, it follows, that 

 the water is colder or warmer, «Having taken 

 a note of this weight, unload the fcale, and 

 place therein the body, whofe fpeciftc gravity 

 is required. Add more weight, till the furface 

 of the water again bifefls the ftem. The dif- 

 ference between the added weight, and the 

 former load, is the weight of the body in air. 

 Place now the body in the lower fcale or difh 

 under water, and add weights in the upper 

 fcale, till the furface of the water once more 

 bifefls the ftem. This laft added weight will 

 be the difference between 1000 grains, and the 

 weight of the body in water, fo illpftrate this 

 by an example. 



N. B. I'he fpecific gravity of lead and tin, 

 (and probably other metals) will vary in the 



third 



