126 Mr Dootson, A Method of detecting Nickel, etc. 



are formed, and that the nickel compound is freely soluble in 

 ether free from excess of acid. That of cobalt is much less so, 

 unless alcohol is present, when it passes readily into the ether. 

 It is possible that the addition of alcohol causes a different 

 molecular arrangement in the case of the cobalt compound. (Vide 

 Treadwell, Zeit. Anorg. Chem. 1901, 108 ; and Rosenheim and 

 Huldschinsky, loc. cit.) 



Experiments show that where decinormal solutions of the 

 chlorides are used, one part of nickel may be detected in presence 

 of 100 parts of cobalt, and one part of cobalt in presence of 50 

 parts of nickel, and that if the method is used comparatively 

 even greater delicacy may be obtained. If either metal, but not 

 both, be present the process is sufficiently sensitive to give the 

 reaction distinctly with less than one-tenth of a milligram. In 

 the hands of students the method has been found to be rapid 

 and reliable. 



