1. On the Purification of Sulphuric Acid.

The author, after describing the different methods, recommended for purifying sulphuric acid from nitric acid, namely, boiling with a little sugar, and heating with sulphate of ammonia, both of which had proved troublesome and imperfect, stated, that after trying various plans, the only one which he found to answer well, was the action of sulphurous acid on the oil of vitriol, after diluting it to the sp. gr. of 1·715, or lower. He adds one volume of water to three of the oil of vitriol, passes sulphurous acid gas through the hot liquid till it is in excess, and then boils off the excess of sulphurous acid; or, still better, three volumes of oil of vitriol are added to or diluted with, one of a saturated solution of sulphurous acid in pure water, and boiled. The acid is thus so perfectly purified from nitric acid, that when used for making hydrochloric acid, it yields a product quite colourless, which was not the case with the oil of vitriol purified by any other process.