A. Glass is a very excellent radiator; and, therefore, most rapidly parts with its heat.
Q. Why is a tumbler of cold water made quite dull with mist, when brought into a room full of people?
A. Because the hot vapour of the room (coming in contact with the cold tumbler) is condensed upon it; and changes its invisible and gaseous form for that of a thick mist.
Q. Why is a glass made quite dull, by laying a hot hand upon it?
A. The insensible perspiration of the hot hand is condensed upon the cold glass, and thus made perceptible.
Q. Why are wine-glasses made quite dull when they are brought into a room full of company?
A. The hot vapour of the room (coming in contact with the cold wine-glasses) is condensed upon them, and covers them with vapour like dew.
Q. Why does this misty appearance go off after a little time?
A. Because the glass becomes of the same temperature as the air of the room, and will no longer chill the vapour which touches it, and condense it into mist.