In the Maltese capital, as in Cairo, there is a fine dust permeating the atmosphere when the wind blows, charged with silex and animal impurities, which finds lodgment in the eyes.
"The Story of Malta"
Maturin M. Ballou
It is a curious fact, and one which requires further examination than it has yet received, that, if this mixture be suffered to remain long at rest before it is worked up, it becomes useless; for it is then found that the silex, which at first was uniformly mixed, becomes aggregated together in small lumps.
"On the Economy of Machinery and Manufactures"
Charles Babbage
They contain in solution so large a quantity of the matter which by mineralogists is denominated silex, that once allow the senses to be overpowered by repeated draughts, and in a few hours the effects which you behold will be produced.
"The Pacha of Many Tales"
Captain Frederick Marryat