Page:Proceedings of the Royal Society of London Vol 1.djvu/504

Rh light, forming a white fusible substance soluble in water, and acrid to the taste, from which iode is again separated by sulphuric acid.

lode was found to combine with chlorine into a yellow volatile solid, from which iode was again separated by solution of potash, not in exoess.

When iode is heated with oxygen gas, or With oxymuriate of pot- ash, it undergoes no change. When heated in the presence of iron, zinc, tin, lead, or mercury, out of the contact of air, it forms com- pounds that are fusible and volatile, and have a yellow, orange, or red colour, excepting the compound formed with zinc, which is white.

The compound of iode and iron, when exposed to an alkaline so- lution, yields oxide of iron, but it combines with dry ammoniacal gas without decomposition; whence the author infers that the formation of oxide depends on the presence of water.

When iode is heated in hydrogen, the gas expands considerably, and the compound is found to be highly acid, rapidly absorbed by water, forming a liquid acid without colour, but becoming tawny by dissolving an excess of iode.

Iode combines with phosphorus, producing heat without light; a solid compound is formed that is fusible and volatile; and a strongly acid gas is extricated, that is readily absorbed by water. When potassium or mercury are heated in this gas, they extricate hydrogen equal to half the volume of the gas, and are found combined with iode; so that this gas appears to arise from the presence of hydrogen probably contained in the phosphorus.

When the fusible compound with phosphorus is acted upon by water and heated, much gas arises that is acid and spontaneously inﬂammable, and the remaining liquid is found to contain hydrophosphorous acid.

When iode is thrown into a moderately strong solution of potash, two compounds are formed, as in the formation of oxymuriate of potash. The ﬁrst appears in crystals, which form immediately, and fall to the bottmn of the solution, and are analogous to hyperoxymu- riate of potash, and very similar to it in properties. But the solution contains a diﬁ'erent salt, without excess of oxygen, being simple iodate of potash. The crystals are sparingly soluble in water, deﬂagrate when mixed with charcoal, and yield abundance of oxygen when heated.

By passing the purple vapour over red-hot potash, oxygen is also expelled; and it appears that oxygen quits the triple compound at a red heat.

The aﬁinities of this body for potassium and the metals are inferior to those of chlorine for the same bodies; and accordingly it is extricated from them when the compounds are exposed to oxymuriatic gas.

Then the compound of iode with potassium is acted upon by sulphuric acid, a different class of phenomena appear in consequence of the decomposition of the acid, and of the water present. Sulphureous acid is disengaged, mixed With the acid gas formed by the union of