PROCEEDINGS 



OF THE 



Cambrifogt ^Ijitosnpljkal Stonrfg, 



Note on the Pulverization of "Nickel-grains" in Fuming Nitric 

 Acid. By Dr W. A. Hollis, Trinity College. 



[Read 26 October 1903.] 



Commercial nickel is obtainable in three forms ; namely, in 

 rolled sheets, as wire, or again as polymorphous lumps, named 

 technically " nickel-grains." The metal in the two former states 

 is after purification submitted to various processes whereby it is 

 rolled or drawn, as the case may be, into the form required ; and 

 it is placed upon the market with the well-known silvery sheen 

 upon its surface. On the other hand nickel-grains are dull, dark 

 gray, nodular masses of metal, offering unmistakable evidence 

 of their crystalline character however, in an occasional solid angle 

 which juts out beyond the roughened surface. The metal is 

 obtained in this state directly from the smelting furnace. The 

 grains vary in weight, from a few grains to a drachm or more 

 each. Messrs Johnson, Matthey and Co., from whom I obtained 

 the specimens I am here describing, inform me that they may be 

 considered to consist of about 98 °/ of pure nickel. The chief 

 impurities are cobalt and iron. 



In common with the two other highly magnetisable metals, iron 

 and cobalt, nickel in the presence of strong HN0 3 , Aq, occasion- 

 ally exhibits the phenomenon of " passivity." According to Morley 

 and Muir (Watt's Diet, of Chemistry, 1892), Saint-Edme (Compt. 

 Rend. 106, 1079) noted that commercial sheet nickel was passive 

 in ordinary nitric acid. I can to some extent confirm and sup- 

 plement this statement. Sheet nickel is only slightly attacked 

 at ordinary temperatures by either strong (s.G. 1'42) or weaker 

 VOL. XII. PT. iv. 17 



