Note whether any moisture condenses on the cooler parts of the tube, a gas is evolved, a sublimate formed, or the substance changes colour.
Bismuth trichloride, BiC13, was obtained by Robert Boyle by heating the metal with corrosive sublimate.
Formaldehyde proved safer and less troublesome than corrosive sublimate, chlorine gas or sulfur dioxide.
Cadmium oxide, CdO, is a brown powder of specific gravity 6.5, which can be prepared by heating the metal in air or in oxygen; or by ignition of the nitrate or carbonate; by heating the metal to a white heat in a current of oxygen it is obtained as a dark red crystalline sublimate.
Volcanic sulphur usually occurs as a sublimate around or on the walls of the vents, and has probably been formed in many cases by the interaction of sulphur dioxide and hydrogen sulphide.
