A YEAR IN SCIENCE 39 



piece. When the ice is almost melted, note again the 

 exact temperature of the water. Weigh again the 

 beaker and its contents. Tabulate the data as follows : 



1. Weight of beaker and cover. 



2. Weight of hot water and beaker. 



3. Weight of hot water (calculated). 



4. Weight of beaker and water at end of experi- 

 ment . 



5. Weight of ice (calculated). 



6. Temperature of water before ice was added. 



7. Temperature of water after ice was melted. 



8. Loss in temperature of water (calculated). 



9. Increase in temperature of ice (calculated). 



Multiply the weight of the hot water by its loss in 

 temperature to obtain the number of calories required 

 to melt the ice and raise it to the final temperature. 

 Multiply the weight of the ice by its increase in tem- 

 perature to obtain the number of calories used in 

 raising its temperature. The difference between these 

 results will give the number of calories used in melting 

 the given amount of ice. How many calories are 

 required to melt one gram of ice? 



Why is the temperature of the atmosphere near a 



:dy of freezing water higher than the temperature 

 the atmosphere a little distance away? 

 Exercise 16. Solution. 



Object: To show the effect of dissolving salt upon 

 the temperature of Avater. 



