270 NEW ZEALAND NATURE-STUDY BOOK 
chipped. This has resulted from overheating. Salt fuses 
at a. moderate temperature, which under certain conditions 
may readily be reached in the process of cooking. Should 
the dishes be raised to this temperature, the glaze will be 
injured. 
All are familiar with the use the farmer makes of Rock 
Salt—how he places pieces in his fields and feed-boxes for 
cattle and horses to lick. 
IV.—TABLE SALT. 
Notice its white colour and glassy lustre, also that 
itis opaque. Let pupils feel it by rubbing it between 
their fingers, and ascertain that it is hard, rough, and 
made up of small grains, i.¢., granular. Call attention 
to Sand which is also made up of grains. Contrast the 
two substances, and make out that, whereas Sand is com- 
posed of little particles without any definite shape, the 
Salt-grains are all alike, the shape of each being cubical. 
These are, in fact, little Salt crystals each with six equal 
and similar faces. Salt is crystalline. | 
Norr.—To see this properly a pocket lens will be required. 
Examine Sugar in the same way, and ascertain that it too is 
crystalline. 
Test for its taste, and, as in the case of Rock Salt, 
require pupils to distinguish between salt, bitter, sour, and 
acid tastes. 
Place some Salt in a beaker of water, and test for its 
solubility—both in cold water and in hot. See Rock 
Salt page 267. 
What has become of the, dissolved Salt? Let pupils 
taste the water. The salt is still in the tumbler, but its 
