2>oes 1fcc Afloat? 195 



mention only one, which is the metal bismuth. 

 If we should melt a sufficient amount to fill an 

 iron flask, such as we have described, and sub- 

 ject it to the same freezing process, the flask 

 will be broken the same as in the experiment 

 made with the water. 



A query arises, Why this phenomenon? 

 Why does water follow a different law in 

 cooling from that of nearly all other sub- 

 stances ? 



This is a case where it is much easier to ask 

 a question than to answer it. When water 

 solidifies at the moment of freezing, crystalli- 

 zation sets in. But what is crystallization? 

 Crystallization is a peculiar arrangement of 

 the molecules of matter, which takes place in 

 some substances when they pass from the 

 liquid to the solid form. The molecules as- 

 sume definite forms and shapes, according to 

 the nature of the substance. When water 

 assumes the solid form under the action of 

 cold the molecules arrange themselves accord- 

 ing to certain definite and fixed laws, the re- 

 sult of which is to increase the bulk to a con- 

 siderable extent over that which the same 

 number of molecules would occupy at a tem- 

 perature of 39 degrees Fahrenheit. Hence, 

 as has been heretofore stated, a given block of 

 solidified water is lighter than the same bulk 

 would be in the fluid state, and this is the rea- 

 son why ice floats. 



