316 Inlelilgcncc and Misccilancous Articles. 



If the cyaniuet of mercury and platinum is diftused in water and 

 treated with hydrosulphiiric acid, we obtain sulphuret of mercury 

 and a colourless fluid with a strong acid reaction, which contains, in 

 solution, a combination of cyanuretof platinum with hydrocyanic acid. 

 If we evaporate this liquid, this new combination presents itself as a 

 greenish yellow substance, with a metallic lustre on the surface, partly 

 gold, partly copper colour; it deliquesces in damp air, and is very easy 

 of solution in water and absolute alcohol, and combines with the al- 

 kalies so as to form double cyanurets. 



If this combination, which on account of its acid pro])erties I shall 

 call [Cyanplatinwasserstoff'saure) a compound of hydrocyanic acid 

 and cyanuret of platinum (H Cy + PtCy), be dissolved in absolute 

 alcohol, and this solution left in the open air to evaporate on a watch- 

 glass or plate of glass, the compound offers to the eye of the observer 

 o peculiar crystallization, and at the same time an interesting but in- 

 describable cameleon-like play of colours. If the dry acid be allowed 

 to deliquesce in moist air and is then evaporated in dry air or in the 

 sunshine, it crystallizes in exceedingly beautiful needles, grouped 

 together like stars, which have a metallic lustre and are sometimes 

 gold-, sometimes copper-coloured, like oxalate of platinum, but still 

 more beautiful than the crystals of the latter. In the light and at a 

 tem])erature of boiling water tliis compound undergoes no change, 

 but when heated to above this point it is decomposed into hydrocyanic 

 acid and cyanuret of platinum. If its solution in alcohol is mixed 

 with some nitric acid we obtain a liquid v;hich evaporates, and 

 heated strongly on a glass plate, forms an exceedingly beautiful pla- 

 tinum mirror. 



There may be formed also a similar compound with iridium (Hy 

 Cy + Ir Cy), whose properties are jierfectly analogous to the above 

 compound with platinum. — Poggendorff^s Annals, 1836, No. 3. 



ON DECREPITATION. 

 M. Baudrimont observes that authors have generally attributed the 

 phsenomena of decrepitation to the presence and sudden vaporization 

 of water, or to the sudden production of aeriform matter. It is re- 

 markable, he observes, however, that the greater number of bodies 

 which decrepitate are really anhydrous and fixed ; such are sulpliate 

 of potash, sulphate of barytes, chloride of sodium, &c. In order to 

 explain this anomaly it is supposed that these substances contain 

 water interposed between their constituent parts. M. Baudrimont 

 found, however, that after drying several fixed and anhydrous bodies 

 in several ways, at a low temperature, as completely as possible, they 

 still decrepitated when quickly heated ; he also observed that the 

 slaty clays mixed with coal decrepitated strongly when thrown into 

 a hot furnace, and that those which presented most surface decrepi- 

 tated the loudest. Slaty clay possesses a well-marked lamellar struc- 

 ture; and it was found that anhydrous bodies susceptible of decrepi- 

 tating did not undergo it, except they were crystallized and pos- 

 sessed a smooth easy cleavage. This disposition to divide evenly on 

 large surfaces offers a ready expianatitm of their decre])itation. In 

 fact, substances which decrepitate, being such as are considered 



