Iodine Blue

: ON THE PRIMARY, BLUE.

It is curious that iodine, which gives a yellow with lead, should also

afford a blue with the same metal. When a solution of iodine in aqueous

soda (carbonate of soda is not so good) is added to nitrate or acetate

of lead-oxide, a transient violet-red precipitate falls, which

decomposes spontaneously under water, yielding iodine and a beautiful

blue powder. The colour, however, is exceedingly fugitive, even the

carbonic acid of the air separating iodine from it and forming a lead

salt. Bearing in mind the scarlet iodide of mercury, iodine is capable

of furnishing the three primary colours, distinguished alike by their

brilliancy and fugacity.



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