471 
for ascertaining Specific Gravities. 
substances in question to persons who have neither time 
or knowledge sufficient to enable them to apply an instru- 
ment of such a kind. 
The hydrometer , on a variety of constructions, has been 
long made use of by distillers and all dealers in spiritu- 
ous liquors ; and of late years brewers have generally 
adopted it, for its simplicity and facility in use compared 
with the hydrostatic balance or weighing bottle. But as 
the hydrometer for spirituous-liquors, and the saccharome- 
ter for malt-liquors, (which the author of this paper is in 
the habit of manufacturing,) are adapted solely to their re- 
spective purposes, he has long thought it a very desirable 
object to construct an instrument which would combine 
simplicity with an universality of application to all sub- 
stances, fluid and solid, of which it might be requisite to 
ascertain the specific gravity. And it is presumed that 
this object is accomplished in the instrument about to be 
described. 
Among the principal subjects of consideration in the 
construction of hydrometers, are, the form of the instru- 
ment which shall be best adapted to facilitate its motion 
in a fluid, and that it be of a convenient size, both 
for the sake of portability, and that it may require as 
small a sample of a fluid as possible to make an experi- 
ment with. 
With these views, the spheroidical form is that which 
has been preferred for the bulb of this instrument, on ac- 
count of its more readily dividing the fluid in its passage 
up and down; and the size of it is such, that half a pint 
of any liquid is sufficient for trial with it.* 
The hydrometer (see plate 15, fig. 5) consists of the bulb 
&, a small stem a c, with a cup d on its top to receive 
weights, and a shank ef beneath the bulb with a point- 
ed screw, to which is affixed a cup g, to receive weights 
* The figure in the engraving of the Emporium is half the size of the origin 
nal drawing. 
