PART II. 



INORGANIC CHEMISTRY. 



CHAPTER I. 



PRELIMINARY REMARKS ON SPECIFIC GRAVITY, 

 NOMENCLATURE, ETC. 



Specific Gravity. — By this is meant the ratio of the weight of 

 a body to its bulk, or the weight of a body compared with the weight 

 of an equal bulk of some standard, which is received as unity. In 

 solids and liquids this standard is pure water at the temperature 

 of 60° F. 



2b find the specific gravity of a liquid,, it is only requisite to 

 weigh equal bulks of that liquid, and water at the same temperature, 

 and then divide the weight of the liquid by the weight of the water ; 

 the quotient will of course be greater or less than unity, as the liquid 

 employed is heavier or lighter than water. Now, the simplest mode 

 ^of weighing equal bulks is to weigh them in succession in the same 

 vessel, taking care to have exactly the same quantity in both cases. 

 Another method is to employ a solid body, as the stopple of a bottle, 

 ascertain how much weight will sink it in the given liquid, and 

 divide this by the weight required to sink it in water ; this is obvi- 

 ously the same as ascertaining the weights of the relative bulks of 

 the two, since a solid body always displaces its own hulk of a liquid. 

 Hydrometers are instruments employed for ascertaining the spe- 

 cific gravity of liquids. They consist of 

 hollow metallic balls, attached to a thin 

 stem, and having a weight beneath, to keep 

 it erect. The use of the hydrometer is very 

 simple. The liquid to be tried is put into a 

 narrow vessel, and the instrument floated in 

 it. It is obvious that, the denser the liquid, 

 the higher will the hydrometer float ; and, 

 vice versa ; the point on the graduated stem 

 will then express the specific gravity. 



To find the specific gravity of a solid. — 

 The principle here is precisely the same as 

 in the case of liquids : the rule being " to 

 divide the weight of a given bulk of the 

 body, by the weight of an equal bulk of 

 water ;" and the mode adopted, is first to 

 weigh the body in the air, then to weigh it in 

 water ; find out how much it loses by being weighed in water, ( w hich will 



Fig. 16. 



