"To ascertain the fixed air, the taste is partly sufficient; but pour into the water some tincture of turnsol, and the water will become more or less red, in proportion to the quantity of fixed air it contains."
Iron.
"The iron may be known by means of the galnut and phlogisticated alkali; the galnut put into feruginous water, will change its colour to purple, or violet, or black; and the phlogisticated alkali will produce immediately Prussian blue."
Copper.
"Copper may be ascertained by means of the phlogisticated alkali or volatile alkali; the first turns the water to a brown red, and the second to a blue. The last mode is the surest, because the volatile alkali precipitates copper only, and not iron."
Sulphur.
"Sulphur and sulphurous vapours may be known by pouring, 1. nitrous acid into the water; if a yellowish or whitish sediment be formed by it, there is sulphur, and at the same time a sulphurous odour will be exhaled and evaporate. 2. By pouring some drops of a solution of corrosive sublimate; if it occasion a white sediment, the water contains only vapours of liver of sulphur; and if the sediment be black, the water contains sulphur only."
Vitriolic Salt.
"Water may contain vitriolic salts; that is salts resulting from the combination of the vitriolic acid with calcareous earth, iron, copper, or with an alkali. The vitriolic acid may be ascertained by pouring some drops of a solution of heavy earth; for then a sandy sediment will be formed, which will settle slowly at the bottom of the vessel."