MIST ON GLASSES. 215 



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. Wliy 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. 



Q. Why is a WINE-GLASS (brought out of a 

 CELLAR into the AIR) covered with a thick MIST in 

 summer-time ? 



A. The vapour of the hot air is 

 condensed by the cold glass, and covers 

 it as a thick mist. 



Q. Why does BREATHING on a GLASS make 

 it quite DULL? 



