80 Tables for reducing Degrees of Benumbs Areometer 
scale of this instrument* It is described by Beaume in 
Iiis Elemens de Pharma cie, p. 466. 
The form of this instrument is that of the common hy- 
drometer, that is, a lengthened bulb or ball with a long 
narrow stem rising from it, which last is graduated, and 
the instrument is so poised that it floats with nearly the 
whole of the stem above the level of the heaviest liquid 
whose density it is to indicate, and with nearly the whole 
of the stem immersed when the lightest liquid is used. 
A single instrument would in strictness suffice to indi- 
cate the density of every liquid from the lightest alcohol 
to the heaviest acid, which would include a range of ac- 
tual specific gravity from about .8 to 2. (water being = 
1.) But an instrument of this kind must be either incon- 
veniently long, or the stem must be very wide, and the 
degrees too minute for tolerable accuracy. Beaume 
therefore very judiciously divided it into two scales, one 
of which is the areometer for spirits and liquors lighter 
than water, and the other the areometer for salts or li- 
quids heavier than water. He has further distinguished 
them by inverting the scales, that is to say, in the instru- 
ment for salts the 0. or zero is at distilled water, and the 
numbers increase with the increasing density of the li- 
quors for which it is used ; whereas in the instrument 
for spirits the numbers increase from the zero with the 
decreasing density. Hence it is necessary to describe 
these two instruments separately. 
The hydrometer for salts was made by Beaume in the 
following way : the instrument was first immersed in wa- 
ter at 18.75° Reaum. = about 50° Fahr. and loaded 
with mercury dropped into the bulb till it sunk so low 
that only the very top of the stem was out of water, 
which point was marked as the 0. of the scale. The in- 
strument was then removed to a solution of common salt, 
containing 15 parts (by weight) of salt to 85 parts of wa- 
