This arises from the production of potassium, and its subsequent oxidation.

The glass formed under the blow-pipe, with nickel and borax [587], which should be brownish, becomes, if potash is present, of a blue colour.

625 RHODIUM : symb R ; equiv.

52-2 It was discovered by Wollaston, in 1803 : and is found in combination with plati- num, and palladium being dissolved out along with them, with aqua regia.

After most of the platinum has been thrown down by sal-ammoniac, and all the palladium, by cyanide of mercury [594], and both are removed, hydrochloric acid is to be added: and the solution is to be evaporated to dryness, to decompose the excess of cyanide of mercury, and change it into a chlo- ride.