On Specific Gravity. 12) 
Arr. XIL—On Specific Gravity. By Rosert Hare, 
M. D. Professor of Chemistry in the University of Penn- 
sylvania. 
A CLEAR conception of Specific Gravity, is toa 
comprehension of the language of the most useful sciences 
and arts. It may be defined, the ratio of the weight ofa 
hody, to its bulk. 
On the means of ascertaining Specific Gravities. 
The object of all the processes for this purpose, is, either 
to ascertain the weight of known bulk, or the bulk of known 
weight. When masses are reduced to the same bulk, it is 
only necessary to weigh them. When they are reduced to 
‘the same weight, it is ed necessary to measure them. 
water were among a number of substances reduced to the 
same bulk, and el hed and its — assumed as a unit, 
the numbers found, would be the same as those now in use to 
express specific gravities. The reuity of water has been 
assumed as the standard, because this fluid may almost al- 
ways be had, sufficiently pure ; and it is generally easy to 
ascertain the weight of a quantity of it, egal in bulk, to 
any other body. 
In order to obtain the specific gravity of a body, therefore, 
we have only to divide its we ies by the weight of a quantity 
of water equal to it in bu 
The weight of a quantity of water, equal to the body in 
i tance which | 
what is necessary to overcome the which a body 
encounters in sinking in water, aid divide, by this weight, 
thus ascertained, the weight of the body, we shall have its 
specific gravity. 
In = case of a body which will sink of itself, the resist- 
ance to its stoking: is what it loses of its weight, when 
weighed in wate 
In the case — a body which will not sink of itself, the re- 
deat to is Sablon, in ice eae to the weight 
which must be used to make it sink. © . 
VOL. L.—no. 1. 16 
