836 PROCEEDINGS OF THE AMERICAN ACADEMY. 



On the other hand, the amounts of nickel in the wash-waters were 

 distinctly weighable, and not to be overlooked. That it was nickel, and 

 not a new metal, there could be no room for doubt, for it gave a black 

 sulphide and a green sulphate, the characteristic pink coloration with 

 potassic thiocarbonate, as well as a beautiful rose-colored flame test, 

 which we have found to be characteristic of nickelous halides. Since 

 the nickel salts are much more easily reduced than those of cobalt (see 

 the next paper), it is harder to obtain a satisfactory flame test in the 

 former case than in the latter. Only when both salts and gas are dry, 

 and the vaporization proceeds in the inner flame, are the best results to 

 be obtained. We have found no reference to this flame reaction of 

 nickel halides in chemical literature,* and one cannot but believe it 

 to have been unknown to Krliss and to Winkler at the time of one 

 of their disputes.! 



The question now arises. Whence came this nickel ? Was it occluded 

 as nickelous bromide in the interior of crystals of sodic bromide, and 

 thus protected from reduction, or was it dissolved as hydroxide from the 

 spongy metal ? The large quantity of nickel present seemed to over- 

 throw the former alternative, but the possibility of the latter is emphati- 

 cally denied by Winkler,t and rejected after some hesitation by Kruss.§ 

 Since the equivalent of nickelous bromide is very near that of sodic bro- 

 mide (109.3 : 103), and the impurity was calculated from the amount of 

 bromine present, the point has no important bearing on the immediate 

 problem; but nevertheless it is always interesting to settle a mooted 

 question of this sort. 



Winkler's experiments were made with coherent nickel coated on the 

 inside of a platinum dish, while Kriiss's experiments were made with spongy 

 metal in porcelain vessels. The former found no trace of any substance 

 in the water in which his nickel had been digested, while the latter found 

 a large residue (most of which must have come from the porcelain), and 

 hastily ascribed this residue to the presence of an unknown element. It 



* Vogel, Spectral Anal, irdisclier Stoffe, pp. 246, 262. 



t Kriiss and Schmidt, Zeitschr. Anorg. Cliem., II. 249; Winkler, Ibid., IV. 17. 

 Kriiss observed the appearance of a pale rose-colored flame during tiie ignition 

 of his nickel in a Rose crucible in hydrogen, accompanied with a loss of weight. 

 If the hydrogen was r/r//, and especially if, as is often the case, it contained traces 

 of hydrochloric acid, minute traces of nickelous chloride might have been sublimed 

 and have caused this phenomenon, which Kriiss ascribed to "gnomium" and 

 Winkler ascribed to potassium. This question is worthy of further attention. 



\ Winkler, Zeitschr. Anorg. Chera., IV. 12. 



§ Kriiss, Zeitschr. Anorg. Chem., II. 2i{8. 



