436 Mr. F. Field on the Neutralization of Colour 
nickel and cobalt from the ordinary speiss by the wet method, 
earried on for many years in Birmingham, this phenomenon 
must have been observed by those employed in conducting the 
process ; and to one ignorant of the fact, and who has devoted 
but little time to this particular branch of chemical analysis, the 
solution of speiss must appear rather surprising, as, although very 
rich both in cobalt and nickel, in certain instances the solution 
appears almost destitute of colour, showing no trace either of the 
red of the cobalt or the green of the nickel. Professor Liebig 
(Liebig’s Annalen, vol. xe. p. 112, and Chemical Gazette, vol. xii. 
p- 300), in remarking upon the decolorizing action of binoxide of 
manganese upon glass, does not impute the bleaching effect to 
the oxidation of the protoxide of iron by the reduction of the bin- 
oxide, as neither nitrate of potash nor other strongly oxidizing 
bodies effect the same change, but to the violet colour imparted 
to the glass by the manganese being complementary to the green 
produced by the iron, and hence the two affording a colourless 
mass. And that this is the case is evident, I imagine; for if 
borax be coloured by protoxide of iron, the resulting glass fused 
in a platinum crucible, and a little of the same salt (previously 
coloured by manganese) cautiously added, a point is arrived at 
where the mixture of the two has lost the individual tint of each 
and produced a nearly colourless glass. Liebig also mentions 
that a concentrated solution of sulphate of manganese having a 
slight rose colour, added to a solution of protosulphate of iron 
having a pale green tint, affords a perfectly colourless mixture. 
A few experiments of my own have been extended to some 
other solutions and chemical compounds. 
When nitrate of cobalt is gradually added to a cold solution of 
bicarbonate of soda, a beautiful amethyst-coloured liquid, at times 
almost approaching to violet, is produced. The colour has not 
the pure rose-red of the nitrate or sulphate of the metal, but 
has evidently a considerable portion of blue in its composition. 
If the fluid thus formed be divided into two equal parts, and to 
one of these a few drops of hypochlorite of soda be added, the 
liquid changes to an intense green colour, with no trace of blue, 
but a slightly yellow tinge, very much the colour of chloride of 
copper when dissolved in : strong hydrochloric acid. If the violet 
and green liquids are united, the mixture becomes colourless, more 
strikingly so perhaps than by the union of the cobalt and nickel 
salts: the blue tint in the bicarbonate of cobalt forms green with 
the slight yellow shade of the peroxidized compound; and this, 
together with the remaining green of that liquid, is entirely neu- 
tralized by the pure rose colour. 
Dilute sulphate of nickel (pale green) dissolves erystallized 
sulphate of manganese (pink), forming a colourless solution. 
