14
Kok II.
Acibs.
This problem has been solved by Mr Kirwan“. He
took sulphuric acid of the specific gravity 2.000, which
is the strongest that can be procured, for his standard,
and the point was to determine how much of this stan
dard acid existed in a given quantity of acid of inferior
density.
He concluded, from a number of experiments with
sulphuric acid, of the specific gravities 1.8846, 1.8689,
1.8042, 1.7500 (for he could not procure an acid of
the specific gravity 2.000 at the temperature of 60°, in
which his experiments were performed), that when
equal parts of standard acid and water are mixed, the
density is increased by th part of the whole mixture.
Then, by applying a formula given by Mr Poujett,
X Irisb Trans. iv.
* Mr Poujet undertook the examination of the specific gravity of al
cohol mixed with different quantities of water. He took for his standard
alcohol whose specific gravity was o.8199, àt the temperature of 65.75°.
He then formed ten mixtures ; the first containing nine measures of al
cohol and one of water, the second eight measures of alcohol and two of
water, and so on till the last contained only one measure of alcohol and
nine of water. He took care that each of these measures should contain
equal bulks, which he ascertained by weight, observing that a measure of
water was to a measure of alcohol as 1 to 0.8199. Thus 10000 grains of
water and 8199 of alcohol formed a mixture containing equal bulks of
each. From the specific gravity of each of these mixtures he discovered
how much they had diminished in bulk in consequence of mixture, by
the following method:
Calling A the real specific gravity of any of the mixtures; B its spe
cific gravity found by calculation, supposing no diminution of bulk ;
n the number of measures composing the whole mass; n — x the number
to which it is reduced in consequence of mutual penetration—it is evi
dent, since the increase of density does not diminish the weight of the
X( d. dr
whole-mass, that » B — n— x X A. Therefore
