As a special acetylene purifier, bleaching-powder exists in at least two chief modifications.
The second modification of bleaching-powder is designated "puratylene," and contains calcium chloride and quick or slaked lime.
The important element in bleaching-powder is the chlorine which it contains.
A solution of bleaching-powder gives with solution of the sulphate a purple colour changing to red-brown.
Arsenic is insoluble in the acid, but immediately dissolves in the bleaching-powder.
The black films of tin, lead and cadmium dissolve at once in the acid, the lead film being also soluble in bleaching-powder.
For this purpose a filtered solution of bleaching-powder and a very dilute solution of nitric acid may be employed.