Improvements iu Science. 447 



It consists of 48 cyanodide of platinum and 52 of cyanodide 

 of mercury, or Pt Cy + Hg Cy. The Cyanodide of Platinum 

 left by the decomposition of the hydrargyro cyanodide of 

 platinum, is a beautiful olive coloured powder, insoluble in 

 water, acids and alkalies ; combustible, leaving by combus- 

 tion 79 per cent, of pure platinum ; giving with oxide of 

 copper and heat, carbonic acid and azote, in the proportion 

 of 2 to 1 volumes, and consequently composed of Pt Cy. 

 If the hydrargyro-cyanuret of platinum diffused in water 

 be treated with sulphuretted hydrogen, sulphuret of mercury 

 is produced, and a colourless strongly acid liquid, which 

 contains in solution a combination of cyanodide of platinum 

 with hydrocyanic acid. If the water is driven off by evapo- 

 ration, this new combination appears in the form of a 

 greenish yellow substance, with the metallic lustre, pre- 

 senting on its surface the colour of gold and copper, which 

 deliquesces in the air ; is very soluble in water and absolute 

 alcohol, and combines with the alkalies to form the double 

 cyanurets of platinum. Dobefeiner, who is the discoverer 

 of these facts, terms this substance hydroplatinocyanic acid. 

 It consists of Pt Hg Cy^. When dissolved in absolute 

 alcohol, and allowed to evaporate, peculiar crystals are ob- 

 served, with a fine play of colours similar to the chameleon. 

 If the dry acid is allowed to deliquesce in a moist atmos- 

 phere, and then allowed to evaporate in dry air or in the 

 solar light, extremely beautiful crystals are formed, grouped 

 in the form of stars, with the metallic lustre, of sometimes a 

 golden and sometimes a copper colour. This acid undergoes 

 no change below 212° ; above this it is decomposed into 

 prussic acid and cyanodide of platinum. If its solution in 

 alcohol be mixed with a little nitric acid, a liquid is pro- 

 duced, which when evaporated on a plate of glass and 

 heated strongly, forms a very beautiful platinum mirror. 

 There is also a hydriridiocyanic acid possessing similar pro- 

 perties.* 



Analysis of iron ores. — Berzelius states the following to 

 be a rapid mode of analyzing these ores. He boils them 

 with chloride of copper slightly acidulated w^ith muriatic 

 acid, then on boiling the residue with carbonate of soda, 

 washing the result, drying and weighing, its weight indi- 

 cates that of the carbon .+ 



* Poggendorffs Ann, xxxvii. 545. t L'Institut, 170. 



