On a mucous membrane or a delicate skin it exerts an irritant action, which occurs more quickly than on a thickened epidermis, such as the scalp, and according to the strength and period of application there may result redness, a blister, or an ulcer.
A piece of iron or steel wire in the circuit of a galvanometer is heated in a flame to bright redness at any point.
This substance dissolves slowly in water, forming arsenic acid; by heating to redness it decomposes into arsenic and oxygen.
It is not volatilized even when heated to redness in a current of hydrogen, and it burns readily to the pentoxide when heated in oxygen.
Any small body which was a good absorber of dark rays was rapidly heated to redness when placed at the focus.