French National Institute. 369 
M. Berthollet had given a method of estimating the de- 
gree of acidity of the different acids, and the degree of alka- 
linity of the different bases, by the quantity required by each 
of these kinds of substances in order to saturate or neutra- 
lize the other completely, so as that the combination may 
evince no sign of acidity or alkalinity. J 
He confirms this method by showing, that the propor- 
tions of these quantities are constant, and that if it requires, 
for instance, twice as much of any kind of acid to saturate 
one base than another, there must be twice as much of 
every other kind of acid to the first than to the second. 
But the degree of resistance of heat does not correspond 
to this force, and it is easier, for example, to decompose by 
fire the carbonate of magnesia than that of lime, although 
the affinity of these two earths for the acid is nearly the 
same. It is that the former carbonate has much more water, 
and, as other experiments show, that water favours the libe~ 
ration of carbonic acid. 
The consequences of these facts to all the branches of 
chemistry, and particularly for the theory of analyses, are 
incalculable. 
The tables of the affinities and a great part of the ana- 
lyses made to this day are invalidated by the above; and in 
short, experience proves that almost all these products have 
need of being revised. For example, M. Klaproth, and 
after him M. Vauquelin, have found a fifth of fluoric acid 
in the topaz, where its existence had never been suspected, 
This stone therefore passes into the class of acidulated sub- 
stances. 
Another mineral, hitherto regarded as a stone, passes into 
the class of the metals : it is that which was formerly called 
oisanile, or octaédral schorl of Dauphiny, and which 
M. Haiiy has recently named anathasis. M. Vauquelin 
found nothing in it but the oxide of titanium, as in the 
other mineral called red schorl. 
This fact is important, because it presents two minerals 
among which chemists cannot yet find any essential diffe- 
rence of composition, although their physical qualities, and 
particularly their crystallization, are all different. 
Vol. 26, No. 104. Jan. 1807. Aa In 
