1. Weigh the slate carefully when dry, steep it in water for 24 hours, run the water off, and weigh again - any difference of weight will show the amount of absorption.

2. Stand the slate in water up to half its height - if it be of bad quality the water will rise in the upper half, but in a good slate no sign of moisture will be seen above the water-line.3

3. Breathe on the slate. If a clayey odour be strongly emitted it may be inferred that the slate will not " weather."4

1 Wray

2 Hunt.

3 Gwilt.

4 Dempsey.