156 Analysis of Scientific Books. 
contain a common element, and no other than carbon has been 
hitherto detected in the diamond; but in charcoal, and also 
in plumbago, chlorine detects a portion of hydrogen, to what- 
ever heat they may have been previously exposed; whence 
the inference seems irresistible, that hydrogen is an essential 
ingredient in those two substances, and, consequently, that a 
difference actually exists, in point of chemical composition, 
between the former and diamond, Our fair authoress would 
have done better, therefore, not to have asserted their identity 
in quite so decided terms. We recommend her to look a little 
more into the Conversations on Chemistry before her second 
edition is published, where she will find the difference between 
charcoal and pure carbon. The latter, indeed, in its crystalline 
form, constitutes diamond *. In the list of metals, wodanium 
is introduced, which Stromeyer’s experiments have pretty suffi- 
ciently shewn never had any existence but in the mistake of 
its discoverer, Lampadius. In the second conversation, the 
consideration of the chemical properties of the elements of 
minerals is continued, and one or two more instances of error 
in our author’s chemistry occur ; for instance, fluorine is called 
a gas, whereas it is the unknown base of fluoric acid, and con- 
sequently we are ignorant what form it would assume if we 
could insulate it. In combination with silicium and boron, it 
constitutes the fluosilicic, and fluoboric acid gases. The com- 
pound of fluorine and hydrogen, in its purest form, is liquid at 
the temperature of 60° Fahr. 
Speaking of ammonia, she says, “its precise nature is not 
well known, but it is suspected to consist of hydrogen, oxygen, 
and nitrogen.” We do not know who entertains such a suspi- 
cion. Nitrogen has been supposed to consist of an unknown 
base and oxygen, and, because it suits his chemical canon, 
Berzelius has assumed it as a fact, and in the tables at the 
end of his Essay on the Theory of Chemical Proportions, has 
given the composition of ammonia, as consisting of one atom 
of nitricum (his imaginary base of nitrogen,) one of oxygen, and 
six of hydrogen ; but no one, that we know of, has supposed it 
to contain both nitrogen and oxygen. Putting hypothesis out 
of the question, ammonia is well known to consist of one 
volume of nitrogen and three volumes of hydrogen, condensed 
into two volumes, 
The third conversation treats of specific gravity, of the hy- 
drostatie balance, of the metals that are, and one that is not, 
(wodunium) of their comparative utility, and of the external 
and physical characters of minerals. This is a pleasing and 
instructive conversation, from which the young reader cannot 
** In vol. ii., p. 2, the expression is more accurate, where diamond is 
said to be “ nearly the same substance as charcoal.” 
