T. L. WalJcer — Temiskamite. 171 



The radiating fibrous masses are built up into arborescent 

 botryoidal forms, the outer surface sometimes covered with 

 niccolite or bismuth or by a very thin layer of some undeter- 

 mined black mineral resembling native arsenic (figure 1). 



Chemical properties. — In strong nitric acid the mineral is 

 attacked with violence accompanied by the evolution of red 

 fumes and the separation of a very small amount of sulphur, 

 which later oxidizes so that complete solution results. In sul- 

 phuric acid the decomposition is slower while in hydrochloric 

 acid the mineral is only very slowly dissolved. Closed tube, 

 a very slight deposit of crystallized arsenious oxide; open 

 tube, abundant deposit of the same oxide, the oxidized residue 

 greenish in color ; plaster cast, coating for arsenic and in 

 smaller degree bismuth ; charcoal alone, the easily fusible 

 mineral melts to a bright bead and oxidizes, covering the char- 

 coal with arsenious acid, the bead after long treatment being 

 magnetic. 



Chemical analysis. — Several grams of this mineral appar- 

 ently free from the associated minerals was selected, ground 

 finely, dried at 110° C. and analyzed with the following result : 



Nickel 49-07$ -f- 58-7 = -8359 ) . . 



Cobalt 1-78^ -f- 59- =-0293) 



Iron trace 



Arsenic.... 46-34$ -h 75- =-6179) 



Sulphur 1-030 -K 82: = "0321 J" * b5UU 



Antimony not determined 



Bismuth # 55$ 



98-72$ 



•8652 -f- 2163 = 4 ratio of Ni + Co, 

 •6500 h- 2163 = 3-005 ratio of As + S. 



From the above analysis and calculation it seems very prob- 

 able that this is a new mineral whose chemical composition 

 may be expressed by the formula (jN"i,Co) 4 .(As,S) 3 or, apart 

 from very small proportions of isomorphous elements, lSTi 4 As 3 . 



The small amount of bismuth, it will be observed, is not 

 included in the above calculation, as it seems probable that it 

 occurs in the form of small particles of native bismuth included 

 in the mineral. 



Although this mineral has not yet been found crystallized it 

 seems reasonable to regard it as a new species, first, because of 

 the exact ratio resulting from the analysis and calculation, and 

 second, because we do not know any minerals which could be 

 mixed so as to produce an aggregate of the above composition. 

 Millerite contains as high a percentage of nickel but in it the 



