It is prepared and kept in lead.

It is employed in accelerators on account of its fluorine.
One small drop on the tongue of a dog causes death.

The operator who wishes to use it should pour some of the liquid for which he intends it into a graduate, or other vessel, and then add the desired quantity of acid.

If by accident any of the spray should fall upon the skin, it should at once be copiously drenched with water.
Sulphuric Acid .-- There are two sorts of this acid: one is an oily, fuming liquid; this is made in Nordhausen, in Saxony, and is commonly called "Nordhausen sulphuric acid," or oil of vitriol.

The other which is the kind used in connection with the Daguerreotype, is common sulphuric acid.