Iodide of Potassium and Platinum. 257 



lena to warrant an exploration. Should the mine ever be wrought, 

 it will yield a rich treat to the mineralogist. I found there crystal- 

 lized and massive* yellow oxide of tungsten, crystallized and mass- 

 ive tungstate of lime, crystallized and massive wolfram,* native bis- 

 muth,* massive oxide of bismuth, acicular sulphuret of bismuth, and 

 native* and auriferous tellurium. These are all in very small quan- 

 tities. Magnetic and common pyrites are abundant, and galena and 

 pyritous copper more rare. The gangue of these minerals, and of 

 many others not mentioned, is a white fetid quartz, which does not 

 seem to form a vein, but a bed of considerable extent, overlying 

 gneiss. Gneiss is the prevailing rock of the country around, and it 

 is often traversed by quartz and granite veins. The granite of the 

 veins is the variety called graphic granite, and precisely similar to 

 that of Goshen, Chesterfield, Willimantic, &ic. and like those veins 

 contains Cleavelandite, beryl, tourmalines blue and black, smoky 

 quartz, he. A bed of limestone overlies the gneiss within a few 

 miles, and is traversed by veins of fluor spar, containing lepidolite, 

 topaz, and some other fine minerals. The country in this vicinity 

 offers all the mineralogical and geological associations of tin ores in 

 Europe, but no tin ore has as yet been found. 



I have some grains of gold, presented to me by the proprietor of 

 the mine, which he said were picked out of the cavities in which 

 pyrites had decomposed. 



VI. Iodide of Potassium and Platinum,, or lodo Platinate of Po' 



tassium. 



This compound has been prepared by M. Lassaigne, by the direct 

 union of the biiodide of platinum with iodide of potassium.f 



It may be more conveniently prepared by adding muriate of plati- 

 num to hydriodate of potassa in solution, leaving a slight excess of 

 the latter, evaporating nearly to dryness, and then washing with al- 

 cohol as long as any color is communicated. 



The double iodide of platinum and potassium, remains in black 

 crystalline grains. It is soluble in water, and gives a fine deep red 

 solution, as M. Lassaigne says, but the color is not permanent accord- 

 ing to my experiments, for in a few minutes a black powder begins to 



♦ Prof. Silliman had before observed this, vide this Journal, Vol. I. pp.312, 316, 

 405, and Vol. IV, pp. 52, 187. 

 + Annales de Chimie et de Physique, Tome li, p. 125. 



Vol. XXVII.— No. 2. 33 



