MAGNETIC PROPERTY OF NICKEL. 287 



heated by the blow pipe, and diflblved it in nitric acid. I Examination of 



boiled the folution until the whole of the metal was converted a P! eceno ; : ™i' 



netical.— bolu— 



into arfeniate of nickel ; I then dropped in a fufficient quan- tion in nitric 



tity of nitrate of lead, and evaporated the liquor at a very a ? ld J eb " , , lld f n > 



i . . • ■ # i i j i • nitrate of lead 



gentle heat, but not quite to dryneis. Alcohol poured into added j evapor. 



this folution precipitated every fait but the nitrate of nickel, nearl y t0 dr y- 

 which had been formed by the double decompofition of the ^ded which 

 arfeniate of nickel and the nitrate of lead. This is the me- diflblved nitrate 

 thod which I ufed in the analyfis of the arfeniated copper ores mc e any * 

 of Cornwall ; and the proportion of arfenic acid, contained in 

 arfeniate of lead, was the ftandard to which I referred thofe 

 ores to afcertain their relative proportions. Thefe experi- 

 ments were published in the Philofophical Tranlaclions for 

 1801. 



After the preceding operations, I evaporated the alcohol of evap. of the af- 



the folution of nitrate of nickel, rediiTolved the metallic fait inf ohol; fo,ution 



in water ; pre- 

 water, and decompofed it by potafh. The oxide, well warned cip. by potaft ; 



and dried, was reduced in a Heflian crucible, lined with lamp r ^u£rion »"* 



iii i • i n • •/* n i n ■ charcoal I It was 



black; and in that ltate it manifefted itrong magnetic proper- Jlrongly magnetic 

 ties. None of the procefies of the reagents I had ufed could Arfe n» c be » n g 

 have communicated iron to the nickel. I then allayed this the'magnetic & 

 fame nickel with a fmall proportion of arfenic in a fimilarcru- property. 

 cible, and found that it had loft its magnetic property. A fmall A little iron did 

 portion of iron added to the mafs did not render it attraclable. not reviVe iu 

 From thefe experiments, often repeated, I believe that arfenic 

 has the power of concealing the magnetic property of nickel". 

 Cobalt appears to be in the fame cafe. I was therefore mil- 

 taken when I announced,,, that thofe metals were not in them- 

 felves magnetic; 



XII. Qn 



