The negative results just mentioned have an especial interest. It is
established that red phosphorus has a higher specific gravity than
white phosphorus, that of the former being 1.96, and that of the
latter 1.82. The author's former researches (_Bulletins de l'Académie
Royale de Belgique_, 49, p. 323, 1880) have shown that if sufficient
pressure is applied to a body capable of assuming several allotropic
states, it takes under pressure the state corresponding to its greatest
density. It is consequently impossible to transform red phosphorus into
white phosphorus by pressure. But we know, on the other hand, that
red sulphur and red phosphorus may be mixed with impunity at common
temperatures without combination ensuing; to produce combination the
temperature must be raised to about 260°, the point of transformation
of red phosphorus into white phosphorus.
It is thus established that red phosphorus must first be changed from
its allotropic condition before entering into combination with sulphur.
The pressure opposing this change renders also the act of combination
impossible; red phosphorus appears to us like a body which has lost its
chemical faculties.
Thus, the combination of an element with itself, _i. e._, its
polymerization, has really the effect of extinguishing its energy,
rendering it incapable of fulfilling certain functions. The chemistry
of red phosphorus, more simple than that of white phosphorus, may be
considered as the chemistry of a deadened body. The phosphorus which
is found in combination with sulphur is phosphorus sulphides, and
that which enters into combinations of other kinds, is certainly not
phosphorus in the red state; it is even possible, if not probable, that
it is not even white phosphorus, but a substance still unknown in the
free state.
We arrive at a similar but more complete conclusion as to the nature
of carbon. It is known that the affinity of carbon for sulphur and
even for oxygen only becomes manifest at a temperature bordering upon
redness. Is not this tantamount to saying that, in order to enter
into combination with another body, carbon, like red phosphorus, must
first change its allotropic condition? This view is supported by the
following considerations: The specific heat of amorphous carbon, and,
_a fortiori_, that of graphite and diamond, form exceptions to the
law of Dulong and Petit; they are too small by more than one-half.
They would be normal if the atomic weight of carbon were greater than
it really is; in other words, free carbon were a polymer of combined
carbon. Rose has found that at a temperature of about 500° the
specific heat of carbon agrees with the law of Dulong and Petit. At
this temperature carbon undergoes a beginning of depolymerization, _i.
e._, its chemical affinities reappear, and it burns readily in oxygen.
Do not these facts show a complete parallelism between the chemical
history of phosphorus and that of carbon?
Crystalline carbon, and even free amorphous carbon, are without
chemical activity at the ordinary temperature; but when, in consequence
of a rise of temperature, they take another state, they are transformed
into a new kind of carbon, constituting a fourth allotropic state, and
endowed with a prodigious capacity of combination. If these conclusions
are well founded, we may venture a step further and ask, if the carbon
which enters into the composition, not of mere organic compounds,
but of organized bodies, is not a carbon of still another allotropic
state characterized by the appearance of new properties or forms of
combination which find their expression in the vital phenomena.
In other words, a derivative of carbon, before forming part of a living
body, must first undergo in its atoms a transformation similar to that
which permits amorphous carbon to enter into the composition of organic
compounds. In this order of ideas the carbon of organic chemistry would
be merely a first deadened form of the carbon of biological chemistry,
while free carbon is merely the defunct remains of the carbon of
organic chemistry.--_Bulletin de la Société Chimique de Paris; Chem.
News._
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