Slate and chalk

[Arun Gupta]

Among the strange manners and customs of the Hindus noted by Alberuni in
11th century India, there is (Sachau translation) :

  "They use black tablets for the children in the schools, and write upon
them along the long side, not the broad side, writing with a white material
from the left to the right.  One would think that the author of the
following verses had meant the Hindus :--

      "How many a writer uses paper as black as charcoal,
       Whilst his pen writes on it with white colour.
       By writing he places a bright day in a dark night,
       Weaving like a weaver, but without adding a woof." "

----
Alberuni found slate and chalk to be strange.  I do not know where the
verses Alberuni gives are from.

It occurred to me that a history of the use of slate and chalk for writing
may be interesting.  Does any such exist ?

-Arun Gupta