The Vaporizing Of Paraffin for High-Speed Motors
(Electric Ignition Type)

8 VAPORIZING OF PARAFFIN. by the air circulated over or through the liquid, they must obviously be of large capacity, and as they have the further disadvantage of being very sensitive to differences of temperature and to density of the parti- cular grade of motor spirit used, all surface or vapour generator carburettors have long since been superseded by apparatus capable of a more accurately determined admixture of the fuel. Carburettors in great variety have been used since the introduction of the motor car, a circumstance explained by the faet that what is required of it is so very mueh more exacting than for any o ther purpose, and are described at considerable length in “Car- burettors, Vaporizers, and Distributing Valves”; but as the treatment of paraffin for use in high-speed motors of the electric ignition type conforms so closely to that for motor spirit, a preliminary study of the leading types of petrol carburettors will be instructive in explanation of some of the difficulties met with in the running of a motor under the extremely variable range of load and speed conditions of an automobile. Injection Carburettors.—One of the most effeetive methods of carburetting air by the direct injection of petrol in the form of a spray consists in the combination of an air-pump, pressure fuel tank, and spray ing nozzle, really a development of the common liand-bulb vaporizer; this methoel, first used in France by Etéve, a most perf eet mixture can be produced for varying speeds under the control of synchronized fuel and air-supply throttles, but entails more complexity of apparatus than is compensated for by any commensurate advantage gained. Another method more widely used than now, is to injeet the fuel in the form of a spray by a small