80 BERTHA'S VISIT TO HER 



stances has a figure for its crystal peculiar to 

 itself, and from which it never varies. Common 

 salt, for instance, dissolved in water, and slowly 

 evaporated, always forms regular cubic crystals 

 of about an eighth of an inch in diameter, and 

 quite transparent ; sugar candy is nothing but 

 sugar crystallized into s/x-sided prisms ; and alum 

 forms itself into beautiful crystals of eight sides. 

 All this you may easily ascertain for yourself by 

 experiment ; and when I have an opportunity of 

 taking you to a smelting house, you will see that 

 in the cooling of melted metals, each metal as- 

 sumes a crystalline shape belonging to itself.' 1 



I asked how, and when, all the crystals and 

 precious stones and salts in the world could ever 

 have been in a fluid state. 



"One thing at a time," said my uncle : " that 

 question would lead us quite away from ice. I 

 was going to tell you, that water, in the same 

 manner as salt or metals, when it ceases to be 

 fluid, which happens at the temperature of 32 

 of Fahrenheit's thermometer, assumes a constant 

 regular form. Now, Bertha," he said, "ex- 

 amine this lump of ice, which was in the broken 

 glass, both with and without your magnifying 

 glass and tell me how it appears." 



I told him, that to my naked eye it seemed as 

 if there were lines crossing and recrossing one 

 another in an uneven manner -, but that, with 

 the glass, it appeared like a collection of little 



