HYDROMETER. 
diomeler. These densities were those of 
pure water, and of* water containing || parts 
of its weight of pure dry common salt in 
solution. The temperature was ten degrees 
of Reaumur above freezing, or 54.5° of 
Fahrenheit. His instrument for salts was 
so balanced, as nearly to sink in pure wa- 
ter. When it was plunged in this safine 
solution, the stem arose in part above the 
surface. The elevated portion was assumed 
to be fifteen degrees, and he divided the 
rest of the stem with a pair of compasses 
into similar degrees. 
It is unnecessary to inquire in this place, 
whether this interval he constant, or how 
far it may be varied by any difference in the 
purity, and more especially the degree of 
dryness of the salt. Neither will it be 
requisite to inquire how far the principle of 
measuring specific gravities by degrees, 
representing equal increments, or decre- 
ments, in the bulk of fluids, of equal weight, 
but different specific gravities, may be of 
value, or the contrary. It does not seem 
probable, that Baum6’s instrument will 
ever become of general use, for which rea- 
son nothing further need be ascertained, 
than the specific gravities corresponding 
with its degrees, in order that such expe- 
riments as have this element among their 
data may be easily understood by chemical 
readers. 
M. Baume, in his “ Elemens de Phar- 
macie," has given a table of the degrees of 
his hydrometer for spirits, indicated by dif- 
ferent mixtures of alcohol and pure water, 
where, he says, the spirit made use of gave 37 
degrees at the freezing pointof water; and in 
a column of the table he states the bulk of 
this spirit, compared with that of an equal 
yveight of water, as 35£ to 30. The last 
proportion answers to a specific gravity of 
0.842, very nearly. A mixture of two 
parts, by weight, of this spirit, with thirty 
of pare water, gave twelve degrees of the 
hydrometer at the freezing point. This 
mixture, therefore, contained 6j parts of 
Blagden’s standard to 100 water ; and by 
Gilpin’s excellent tables, its specific gravity 
must have been 0.9915. By the same ta- 
bles, these specific gravities of 0.842 and 
0 9915 would, at 10° Reaumur, or 55? 
Fahrenheit, have fallen to 0.832 and 0.9905. 
Here then are two specific gravities of 
spirit corresponding with the degrees 12 
and 37, whence the following table is con- 
structed. 
baume’s hydrometer for spirits. 
Temperature 55° Fahrenheit, or 10° Reau- 
mur. 
Deg. Sp. Grav. 
Deg. Sp. Grav. 
10 = 1.000 
26 — .892 
11 = .990 
27 = .886 
12 = .985 
28 = .880 
13 = .977 
29 = .874 
14= .970 
30 = .868 
15 = .963 
31 = .862 
16 = .955 
32 = .857 
17 = .949 
33 = .852 
18 = .942 
34 = .847 
19 = .935 
35 = .842 
20 = .928 
36 = .837 
21 = .922 
37 = .832 
22= .915 
38 = .827 
23 = .909 
39 = .822 
24 = .903 
40 = .817 
25 = .897 
With regard to the hydrometer for salts, 
the learned author of the first part of the 
^ H MOlf pi OVIO(') i o filniT t An rln !\/T ArtTAAi, J9 
“ Encyclopedic, Guyton de Morveau,” who 
by no means considers this an accurate in- 
strument, affirms, that the sixty-sixth de- 
gree corresponds nearly with a specific gra- 
vity of 1.848 ; and as this number lies near 
the extreme of the scale, I shall use it to de- 
duce the rest. 
baume’s hydrometer for salts. 
Temperature 55° Fahrenheit, or 10° Reau- 
mur. 
Deg. Sp. Grav. 
Deg- Sp. (xrav. 
0 = 1.000 
39 = 1.373 
3 = 1.020 
42 = 1.414 
6 = 1.040 
45 = 1.455 
9 = 1.064 
48 = 1.500 
12 = 1.089 
51 = 1.547 
15 = 1.114 
54 = 1.594 
18 = 1.140 
57 = 1.659 
21 = 1.170 
60 = 1.717 
24 = 1.200 
63 = 1.779 
27 '= 1.230 
66 = 1.848 
30 = 1.261 
69 = 1.920 
33 = 1.295 
72 = 2.000 
36 = 1.333 
It may not be amiss to add, however, 
that in the Philosophical Magazine, Mr. 
Bingley, the assay-master of the Mint, has 
given the following numbers as the specific 
gravity of nitric acid, found to answer to 
the degrees of an areometer of Baum£ by 
actual trial ; temperature about 60° Fah- 
renheit. But his appears to have been a 
