o three or four ounces of pulverized chalk or marble, moistened in a flask, with an equal quantity of water, add one ounce of sulphuric acid;—carbonic acid gas will be evolved in abundance, and will rise through the neck of the flask, and may be conducted by pipes, to any proper receiver. Instead of the marble or chalk, substitute granulated zinc;—in this case hydrogen gas will be evolved; but this may require a larger proportion of water. Pour sulphuric acid upon a similar quantity of dry muriate of soda;—muriatic acid gas will be rapidly evolved. Proceed in the same manner with a similar quantity of black oxide of manganese,—apply the heat of a lamp, and oxygen gas will be produced. Put into the flask, two or three ounces of lean beef, cut into small pieces; pour over them one ounce of nitric acid diluted with three ounces of water; apply the heat of a lamp, and nitrogen gas will be liberated. Powder separately, equal quantities of muriate of ammonia and newly burnt lime; put them together into a flask and apply gentle heat; ammoniacal gas will be evolved. Pour an ounce of nitric acid, diluted with five times its weight of water, upon one ounce of shreds or turnings of copper; nitrous gas will be rapidly evolved. Grind three parts of muriate of soda with two parts of black oxide of manganese; introduce this mixture into the flask, and add two parts of sulphuric acid, diluted with an equal quantity of water; apply a gentle heat and chlorine gas will be evolved. Note.—When either of the last mentioned gases are produced, great caution is requisite that they do not escape into the room, in any considerable quantity, as their action on the lungs is exceedingly injurious.