so 



ON PURE NICKEti 



Characters of 



ieht. 



hammered metal. I have poured nitric acid on nickel both in 

 buttons and laminated, expecting a very acVive folution; but 

 it has proceeded flowly, and I have even been obliged to havei 

 recourfe to the heat of a fpirit lamp to accelerate it. Thedif- 

 foiution however having appeared to ceafe, I decanted the 

 liquid and poured on the refiduum a frefh quantity of acid of 

 the fame ftrength as the preceding, when on a fudden fuch a 

 brilk action came on, accompanied with the evolution of heat *, 

 that I could not remove the capfule to the fire-place quickly 

 enough, 6 



I (hall now go on to confider fome of the characters of pure 

 nickel in the (late of oxidation. 



The nitric folution of pure nickel has a beautiful grafs-green 

 oxide ot nickfcl. co j our> Carbonate of potafii feparates from it a pale apple 

 Precipitate very greei'P^ recipkate. This precipitate well wathed and dried 

 is ve'ri^i* t. A thoufand parts of metallic nickel reduced to 

 this pre'eipfrtate weigh 2,927 parts. 



If this precipitate be expofed to a white heat it becomes of 

 a blackith gray, fcarcely inclining to green, and weighing 

 only 1,285. On continuing the fire, the mafs approaches the 

 metallic ftate more and more, and becomes magnetic. This is 

 effected much more fpeedily if the oxide be moiftened with a 

 little oil. # 



On adding cauftic ammonia In excels to a nitric folution of 

 nickel, a precipitate is formed, refembling in colour ammoni- 

 ure of copper, but not fo deep. This colour fometimes 

 changes in a couple of hours to an amethyft red, and to a vi- 

 olet, which colours are concerted into an apple-green on the 

 addition of an acid, and again to a blue and violet on the ad- 

 dition of ammonia. If however we add to the folution of 

 nickel a folution of copper, fo as to produce no perceptible 

 change, the colour of the precipitate formed by ammonia 

 ceafes to atTumea red tinge, and the red colour of the ammo- 

 niure of nickel difappears on the addition of a little ammoni- 

 ure of copper ; whence it follows, that every precipitate of 

 nickel by ammonia, which retains its blue colour, has copper 

 combined with it. 



Oil promotes 

 its reduction. 



Precipitate by 

 ammonia. 



Irs being a noble * From this it Is difficult to believe that nickel, under favour- 

 cuaal ^ucition- a ble circumftances, would not become oxided by the combined in- 

 ei * fluenceof air and fire. Van Mons, 



On 



