Page:Proceedings of the Royal Society of London Vol 2.djvu/77

Rh, which the inhabitants wash out for their own consumption; but it is very impure, from a mixture of bitter purgative salt along with it.

There are here many warm springs, of which several are as much as 8° above the surrounding atmosphere; and one of them was at 90°, while the temperature of the air was only 73°.

Among the vegetable productions of this country observed by Mr. Mornay, is one very remarkable for the light which it yields when cut. It is described as a climbing plant, destitute of leaves, and without thorns. It contains a milky juice, which exudes as soon as the plant is wounded, and appears luminous for several seconds. This juice is extremely acrid, so as to blister the skin, even of quadrupeds, to which it is applied. It becomes viscid by drying, and turns of a greenish-yellow colour, appearing to be a gum-resin. It is conjectured that this plant may be an Euphorbium; but as the author had not the good fortune to find it in flower, he had not the means of learning with certainty to which tribe of plants it may belong. 



The observations here added as an Appendix to Mr. Mornay's paper, relate to the crystalline texture of the mass, and its magnetic qualities. The experiments were undertaken for the purpose of ascertaining the presence of nickel more certainly than Mr. Mornay had been enabled to do, and also to discover the quantity of this ingredient.

The crystalline forms in which this iron breaks, are such as are common to many metallic substances; the regular octohedron, tetrahedron, or rhomboid, consisting of these two combined.

With respect to magnetism, it is observed, that the fragments are precisely like any pieces of the best soft iron, easily obeying the magnet, and instantly assuming polarity, according to the direction in which they are placed with reference to the magnetic meridian, and as instantly changing it when reversed. And hence it is inferred that the magnetic polarity of the mass is solely from similar induction.

For detecting the presence of nickel, the author dissolves a very small portion in nitric acid, evaporates to dryness; and after dissolving the oxide of nickel in pure ammonia, he precipitates by triple prussiate of potash.

But for determining its quantity, he adds sulphuric acid to the ammoniacal solution; and after evaporating to dryness, he expels the ammoniacal salts by heat, and then dissolves the residuum, which is mere sulphate of nickel, and, by crystallization, obtains it in a state from which the quantity of metallic nickel can be inferred. By this process he found four per cent. of nickel in this specimen of native