45 



salt, 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. 



Observations and Experiments on the Mass of native Iron found in 

 Brasil. By William Hyde Wollaston, M.D. Sec. R.S. Read 

 May 16, 1816. [Phil. Trans. 1816, p. 281.] 



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 in- 

 gredient. 



The crystalline forms in which this iron breaks, are such as are 

 common to many metallic substances ; the regular octohedron, tetra- 

 hedron, 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 reve.rsed. And hence it is inferred 

 that the magnetic polarity of the mass is solely from similar induc- 

 tion. 



For detecting the presence of nickel, the author dissolves a very 

 small portion in nitric acid, evaporates to dryness ; and after dis- 

 solving 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 



