Adeney&Shegog — IFet and Dry Methods in Chemical Analysis. 101 



On examining Plattner's work carefully, it was seen that no 

 exact experimental evidence was given by him in support of his 

 classification of the metals into " reducible " and " non-reducible," 

 according to their behaviour on fusion with borax and sodium 

 carbonate on charcoal, in the reducing flame. 



It became evident to us from tliese and other preliminary 

 experiments, that Plattner's method was not one by which easily 

 reducible oxides and difficultly reducible oxides could under all 

 couditions be completely separated. The same may be said of 

 Egleston's method. 



The results, however, obtained by Mr. Forth in the analysis of 

 smaltine and tin pyrites were, as above stated, so satisfactory as to 

 convince us of the value of the method if carefully worked out. 

 We therefore determined to make an exhaustive series of experi- 

 ments, in order to ascertain exactly how the various metals behave 

 when their compounds are fused with borax and sodium carbonate 

 on cliarcoal in the reducing flame in presence of silver. 



We were further encouraged to make these experiments by 

 some quantitative estimations of the nickel, cobalt, bismuth, and 

 copper in the smaltine, made by Dr. L. Davoren, who was at that 

 time studying in the laboratory of the Royal College of Science. 

 Dr. Davoren determined these constituents both by the ordinary 

 wet method and by tlie proposed combination of wet and dry 

 processes. His results were as follows : — 



By ordinary wet method. By wet and dry processes. 



Per cent. Per cent. 



Mckel, 7-60 



Cobalt, 3-73 



Bismuth, 2-32 



Copper, 1-80 



. . 7-31 



. . 3-92 



I. 3-33 



II. 3-35 



III. 3-33 



. . 2-06 



tosses it off into a porcelain dish, and repeats this operation until a number of beads 

 have been obtained. He then treats the beads on charcoal with lead, silver, or gold in 

 the reducing flame ; separates the metallic from the glass bead, and examines each 

 separately by dry methods. The only use he makes of the wet way is in the examina- 

 tion of the borax bead for chromium, titanium, molybdenum, niobium, tungsten, and 

 vanadium. 



The metals which, according to him, may be present in the metallic bead, are — 

 nickel, copper, silver, gold, tin, lead, and bismuth (tin, lead, and bismuth being partially 

 volatilized). 



