Barii ferrocyanidum, L. From pure ferrocyanide of iron digested in baryta water.
A portion of this baryta water is then made to act upon a definite quantity of air.
It may be readily recognized by the white precipitate which it forms when passed through lime or baryta water.
The carbonic acid is absorbed by baryta water in three bulb apparatus.
The baryta water is best kept in the bottle represented below.