The pumps act on anhydrous sulphurous acid contained in the cylindrical receiver c. The pressure in this receiver is such that the sulphurous acid is evaporated from it at a temperature of 65° C. below zero.
The sulphurous acid is forced by the pumps into a condenser, d, cooled by a current of cold water; here it liquefies at the temperature of 25° above zero, and at a pressure of about 2-3/4 atmospheres.
The sulphurous acid returns to the receiver C as it liquefies by the little tube _d_.
E and F are two pumps resembling the preceding, and coupled in the same manner. They act upon carbonic acid contained in a cylindrical receiver H.
The temperature in this latter receiver is such that the carbonic acid evaporates from it at a temperature of 140° C. below zero.
The carbonic acid forced on by the pumps is driven into the condenser K, enclosed in the sulphurous acid receiver C, which has a temperature of 65° below zero; the carbonic acid here becomes liquefied at a pressure of five atmospheres.
The carbonic acid, in proportion as it liquefies, returns to the receptacle H by the small tube _k_.
L is a retort of wrought iron, sufficiently thick to resist a pressure of 500 atmospheres. It contains chlorate of potassium, and is heated in such a manner as to give off pure oxygen. It communicates by a tubulure with an inclined tube, M, made of very thick glass, one metre in length, which is enveloped by the receiver, H, containing carbonic acid at the temperature of 140° below zero.
A tap, N, situated upon the tubulure of the retort, permits of the opening of an orifice, P, which leads into the surrounding air.
After the four pumps have been worked for several hours by means of a steam engine of 15-horse power, and when all the oxygen has been disengaged, the pressure in the glass tube is 320 atmospheres, and the temperature at 140° below zero.
Upon suddenly opening the orifice, P, the oxygen escapes with violence, producing, in doing so, so considerable an expansion and absorption of heat as to cause a liquefied portion to appear in the glass tube, and to spirt out from the orifice when the apparatus is sloped.
It ought to be stated that the quantity of liquefied oxygen contained in the tube one metre long and 0·01 m. in internal diameter, occupied about a third of its length, and issued from the orifice P in the form of a liquid jet.