Q. Why are carriage windows very soon covered with thick mist?
A. The warm vapour of the carriage is condensed the moment it touches the cold glass, and covers it over with a thick mist.
Q. Why is the glass window cold enough to condense the vapour of the carriage?
A. Because the inside of the carriage is much warmer than the outside, and the glass window is made cold by contact with the external air.
Q. Where does the warm vapour of the carriage come from?
A. The warm breath and insensible perspiration of the persons riding in the carriage, load the air of it with warm vapour.
Q. What is the cause of the pretty frost-work seen on bed-room windows in winter-time?
A. The breath and insensible perspiration of the sleeper (coming in contact with the ice-cold window) is frozen by the cold glass, and forms those beautiful appearances seen in our bed-rooms in a winter morning.
Q. Why is the glass of a window colder than the walls of a room?