A third preparation was made like the first and second and analyzed.
Analysis:
| Amount | of | chloride | used | .2832 | gr. |
| ” | ” | cadmium | found | .18244 | ” |
| ” | ” | chlorine | ” | .10123 | ” |
| Cadmium. | Chlorine. | ||||
| 64.42 per cent. | 35.74 per cent. | ||||
When the new substance is heated it fuses to a red liquid and then breaks up into metal and the chloride of cadmium. Its reactions are in general those of a strong reducing agent. Treated with nitric acid, oxides of nitrogen are liberated. With dilute hydrochloric, sulphuric and acetic acids it gives free hydrogen. In the presence of dilute acids it reduces mercuric to mercurous chloride, or to metallic mercury.
Three determinations of the reducing power of the substance were made with a freshly prepared specimen, by dissolving weighed portions in hydrochloric acid and measuring the hydrogen liberated.
The following results were obtained:
| Hydrogen found. | Hydrogen calculated for Cd₄Cl₇. | ||
|---|---|---|---|
| 1ˢᵗ | determination | 15.67 c.c. | 15.65 c.c. |
| 2ⁿᵈ | ” | 11.80 c.c. | 11.82 c.c. |
| 3ʳᵈ | ” | 23.00 c.c. | 23.03 c.c. |
An examination of the analyses shows beyond question that the substance formed by the action of metallic cadmium on the molten anhydrous chloride is of definite composition. The proportion of cadmium to chlorine could not be changed even when the substance was heated with the metal for twenty hours, while a very short time was sufficient for its formation when the metal and chloride were melted together.
It may be possible that a substance possessing these properties is not a definite chemical compound but a mixture of cadmous and cadmic chlorides or a solution of one in the other.
If it were a solution it is difficult to see why the composition of the solution should be so constant, since the solubility of a substance is generally altered by a change in temperature. The different preparations were not made at exactly the same temperature yet the composition of the different preparations was the same.