312 NEW ZEALAND NATURE-STUDY BOOK 
Obtain, if possible, a vessel made of Slate, or hollow out 
a small cavity in one of the specimens, fill with water and 
notice that the liquid does not pass through. Take out the 
pieces of Shale and Slate previously immersed in water, and, 
after wiping the moisture from the surface, carefully weigh 
and compare with the weights already taken. Notice that 
both have increased in weight—but that the Shale has 
increased in a greater degree than the Slate. As the 
additional weight is due to the water absorbed, a relatively 
small amount of water must have passed into the Slate. 
NotE.—The softer kinds of Slate absorb a good deal of water; 
it is the harder kinds that are impermeable. ' 
Determine the specific gravity and compare with other 
rocks. 
Uses, Its lightness, the readiness with which it can be 
split into thin pieces, and its power of keeping water from 
passing through, make Slate valuable as a roofing material, 
It is sometimes used to put between the bricks at the lower 
parts of houses, to prevent the moisture which is always 
rising from the ground passing up into the bricks. It is 
also used for school slates, baths, water cisterns, shelves, 
chimney-pieces, and for paving streets. 
Where found, Typical fissile Slate has not been found 
in New Zealand. It occurs in great abundance in Wales, 
also in Scotland and Ireland. The Welsh Slate quarries 
have long been famous, and still supply a large quantity 
of the material used in the British Possessions. The 
rock is hewn out of the quarry, and either split or sawn 
into the shapes required. 
Notr.—The Metamorphic rocks will prove of most interest in 
a district where these are obtainable—indeed with the exception 
of Slate—which could be examined apart from considerations as 
to its origin—it is very questionable whether, under any other 
circumstances, the Metamorphic rocks should be dealt with at 
all. If the district is one in which Metamorphic rocks occur, an 
examination of the Schists should precede that of the Slate. 
