16 ELEMENTARY GENERAL SCIENCE : <CHAP. 



it ; then melt the ice by warming the flask, and show thai*-, the 

 counterpoise is unaltered. 



EXPT. 22. Put some warm water in a flask and some salt in 

 a piece of paper. Counterpoise the flask of water and the 

 paper of salt together and then dissolve the salt in the water. 

 The total weight remains unaltered. 



No kind of Matter can be destroyed. There is a certain 

 fixed amount of matter in the universe which never gets any less 

 and never any greater. If we confine our attention to the earth, 

 we cannot say that it never receives an addition to the matter of 

 which it is built, for every year it is receiving numbers of small 



FIG. 10. Condensation of Steam. 



solid bodies which are continually falling upon its surface from 

 outside space. But the proposition means that in those cases in 

 which it is popularly supposed there is a loss of matter, for 

 instance when a fire burns out, no such destruction has taken 

 place, but only a change in the form assumed by the matter. 

 It will make the statement quite clear if we follow out what 

 really takes place when a candle burns, and, as it would seem, 

 gradually disappears. 



EXPT. 23. Over a burning candle hold a white glass bottle 

 which has been carefully dried inside and out. Observe that 

 the inside of the bottle becomes covered with mist and after a 

 short time drops of liquid are formed which run down the 



