130 Domestic Science 



(c) Solid bodies made of different substances 

 expand to different extents when similarly heated. 



(d) Liquids also vary with respect to the increase 

 shown when heated under similar conditions. 



We have not yet made any experiment with gases 

 from which we can strictly compare their behaviour 

 when similarly heated. For the present we may state 

 that equal volumes of all gases show increases of volume 

 which are practically identical when their temperatures 

 are raised by equal amounts. 



Condensing our observations into a single statement, 

 this is as follows : 



One effect of heat upon bodies is to increase their 

 volumes. 



85. Some further experiments will afford us infor- 

 mation with regard to another notable change in a body 

 which may be brought about under the influence of 

 heat. 



EXPERIMENT 43. Fill a small porcelain dish with 

 lumps of ice. Heat the dish over a small Bunsen 

 flame and note the effect produced on the ice. Continue 

 the heating till the water boils. Boil it steadily, so that 

 no liquid can spirt out of the dish. When no further 

 change can be noted, remove the burner and examine 

 the contents of the dish. 



If clean ice be used, some of our observations will 

 be that the solid ice becomes liquid water, that the 

 liquid, after further heating, disappears, and that no 

 appreciable quantity of matter is left in the dish. 

 Since we are unable to see the substance into which the 

 ice is finally changed, we might incorrectly infer that 

 the matter contained in the ice no longer exists. This 

 is not the case, however, and the matter of the ice is 

 still in existence, after the completion of the experiment, 



