9. Sulphur and Copper.—Three compressions complete the combination. When the product of the compression is heated, there is no development of heat or light.
10. Sulphur and Tin.—Three compressions give a block which yields a yellowish-gray powder, easily soluble in a hot solution of sodium sulphide. Stannic sulphide is therefore formed by the compression of sulphur and tin.
11. Sulphur and Antimony.—After two compressions we obtain a gray-black mass having the color and luster of stibine. When powdered it dissolves with ease in hot hydrochloric acid, giving off hydrogen sulphide.
12. Sulphur and Red Phosphorus; Sulphur and Carbon.—Result entirely nil; there is produced not the least trace of phosphorus sulphide nor of carbon sulphide.
CONCLUSIONS TO BE DRAWN FROM THESE FACTS.
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.