The design of the processes described in this memoir was to decompose the bicyanuret of mercury at such a temperature, and under such a degree of pressure, as to secure the simultaneous extrication of the two equivalents of cyanogen, or their elements, in the expectation that they should come off united, and produce the interesting compound of nitrogen and carbon, isomeric with cyanogen, Paracyanogen : And that result was sought in the belief that it would illustrate the chemical theorem of the existence of bodies which, though composed of the same elements in the same proportions, yet differ as widely from each other in chemical properties and mechanical conditions, as one element differs from another.