OF JAMES SMITHSON. 149 



crystals of quartz, and contains pyrites disseminated in it, which are 

 probably auriferous. 



No. 25. Arseniate of iron. Paris, September 25, 1820. 



1. Nitric acid was put on to some native arsenuret of cobalt to form nitrate 

 of cobalt, and this matter formed as a sulphur colored powder in the mix- 

 ture. It was washed and dried. 



2. Heated in a tube some water and crystals of arsenious acid sublimed 

 and a dark mass remained. 



3. This dark mass heated on coal at the blow-pipe emitted fumes prob- 

 ably of arsenious acid and became like a scoria of iron, but the magnet did 

 not effect it. 



4. The scoria-like mass dissolved in borax with effervesence and spread 

 much on the coal. This glass in the whole looked black, but where there 

 were air-bubbles it had the color of chrysoberyl. 



5. This borax was heated in dilute muriatic acid in a tube. The acid 

 quickly became yellow. 



Prussiate of soda and iron formed an abundant precipitate of prussian 

 blue ; but nitrate of silver formed only a white curdy precipitate of chlo- 

 ride of silver, and no arseniate of silver. 



It is probable, however, that the above yellow powder is arseniate or ar- 

 senite of iron. 



No. 955. Paris, May, 1819. 



1. In Mr. Stockhausen's catalogue this is called mountain cork, and said 

 to be from Dauphenee. 



Both the black fibrous part and the white part, when held in the flame 

 of a candle, take fire and burn with a large flame. 



When the white part was tried, a fluid matter like oil flowed from it and 

 ran along the lips of the pincers, and on cooling set with a crystalline tex- 

 ture. The color was greenish, and it was soft and brittle like spermacite. 



No foetid animal smell was perceived during the combustion. 



The matter is more' like adiposcere than mountain cork. 



No. 1166. Octahedral crystals from Clausthal. 



1. These crystals are easily broken. 



2. Put into pure muriatic acid, the fragments of it did not suffer any 

 change. 



3. Per se, at the blow r pipe they did not decrepitate, but readily reduced 

 to a white metal, which exhaled. 



4. They dissolve in borax with effervescence, without coloring it. Balls 

 of a white metal were produced, but when the borax became fluid it soaked 

 into the charcoal like alkali, and the whole disappeared. 



5. The form of the crystals is regular octahedral, with the six points cut 

 off. 



6. Their color is gray, and their aspect metallic. 



7. Their fracture is perfectly tubular and parallel to the six corners of 

 the octahedron. Their true form is a cube, fissile, parallel to its six faces. 



N. B. These are, most probably, common sulphuret of lead. 



No. 1564. Native gold from the Edder, a river in Hessia, 

 in Germany. 



I had it from Capt. Stockhausen's cabinet. 

 N. B. It is only mica. 



