374 Analyses of Books. [May, 
And Mr. CErsted acknowledges his obligations to the same work. 
This may serve, in some measure, to account for the similarity 
of our opinions. 
The primary compounds, or the corps brulées, as CErsted calls 
them, may, he thinks, be also arranged in a series beginning 
with those bodies which possess the character of alkalmity in 
the greatest perfection, and terminating with those which are 
most completely acid. Of course the bodies in the middle of 
the series possess but little either of alkalinity or acidity, or m 
other words, combine with little energy either with acids or 
alkalies ; but are notwithstanding capable of entering to com- 
bination with both. An acid, of course, is a body capable of 
combining with, and of neutralizing the properties of, alkalies ; 
while an alkali or a base is a body capable of uniting with, and 
neutralizing the properties of, an acid. This was the definition 
given long ago of these bodies by Sir Isaac Newton. It is the 
notion adopted by Berthollet in his Chemical Statics. It is the 
opinion of CErsted, and is the only cpinion which the present 
state of our knowledge will admit. Of course bodies of this 
series are capable of uniting with each other, and those at the 
two extremities of the series unite with most energy. The 
affinities which they exert are of a peculiar kind. They 
have been more studied than any other department of che- 
may The compounds which they form are usually called 
salts. 
The third series of M. CErsted consists of those bodies which 
I have distinguished by the name of secondary compounds, and to 
which he is satisfied with giving the name of salts. 
Thus GErsted divides chemical bodies into simple primary 
compounds and secondary compounds; and he thinks that 
the fadies belonging to each may be disposed in a regular 
series. 
In the first series there are many ductile bodies ; in the second 
and third series there are none. 
Most bodies in the first series are opaque; most of those in 
the two others are transparent. . 
Those belonging to the second class are (with a few excep- 
tions) much less fusible than those of the first class, and at the 
same time much harder. Those of the third class are much less 
fusible than we should expect from the fusibility of their consti- 
tuents, especially when composed of the most energetic acids 
and alkalies, | 
The bodies of the first class are usually good conductors of 
electricity, Those of the second class are almost all bad con- 
ductors while they remain solid, but become better when reduced 
to a state of liquidity ; though not so good as those of the first 
class. Those of the third class are all bad conductors while 
solid; but when they contain much water, they acquire the 
property of conducting electricity, 
