Iodic acid, called also oxy-iodine, (prepared by exposing iodine to the action of euchlorine,) when heated in contact with inflammable substances, and the more combustible metals, will produce detonations.
It appears, however, that sulphur has a stronger affinity for oxygen than iodine has, and iodine a stronger affinity than chlorine for the same element. Hence chloric acid is more readily decomposed by inflammable bodies than iodic acid, and iodic acid, sooner than sulphuric acid.
The acids, which chlorine, iodine, and sulphur form respectively with oxygen, Gay-Lussac remarks, have their elements more strongly condensed, than the same substances united with hydrogen.
Sect. XXXI. Of Detonating Oil, or Chloride of Azote.
This oil is produced by the action of chlorine on ammonia, by using some of the salts of this alkali. A small jar of chlorine gas is transferred into a basin, containing a solution of nitrate or muriate of ammonia, a little heated: an absorption will gradually take place, and the gas be condensed. An oily film will now appear on the surface of the ammoniacal solution, which, as it increases, will form globules and fall through the liquor. This substance is the detonating oil, composed, according to analysis, of chlorine, azote, and hydrogen. It is supposed by Messrs. Wilson, Porret, and Kirk, that the hydrogen serves as a medium of union between the chlorine and azote, and that, in detonation, the powerful effect is owing to the chlorine.
Detonating oil explodes violently at 212 degrees; and even when touched with cold inflammable substances, as a portion of olive oil, about the size of a pin's head, the detonation is also violent, and the vessel, in which the experiment is made, will, in most cases, be broken into fragments.
Detonating oil is considered, however, a chloride of azote. In order to prevent the decomposition of the chloride by the ammoniacal salt, a thin stratum of muriate of soda, put into the bottom of the vessel, is recommended. Its specific gravity is 1.653. Warm water, put into a vessel containing it, will change it to an aeriform fluid of an orange colour. "I attempted," says Sir H. Davy, "to collect the products of the new substances, by applying the heat of a spirit-lamp to a globule of it, confined in a curved glass tube over water: a little gas was at first extricated; but, long before the water had attained the temperature of ebullition, a violent flash of light was perceived, with a sharp report; the tube and glass were broken into small fragments, and I received a severe wound in the transparent cornea of the eye, which has produced a considerable inflammation of the eye, and obliges me to make this communication by an amanuensis. This experiment proves what extreme caution is necessary in operating on this substance; for the quantity I used was scarcely as large as a grain of mustard seed." Phil. Trans. 1813, Part I.
In vacuo, it expands into vapour, which still possesses the power of exploding by heat. In water, it gradually disappears, the water becoming acid, and azote being evolved. Mercury decomposes it, and a white powder (calomel) is formed, while the azote is set at liberty.
Dr. Ure (Chemical Dictionary, Art. Nitrogen,) observes, that the mechanical force of this compound, seems superior to that of any other known substance, not even excepting the ammoniacal fulminating silver. The velocity of its action appears to be likewise greater.