726 REPORT— 1889. 



nations of carbon and hydrogen, each of which is distinguished by some special 

 property. At ordinary temperatures and pressures some are gaseous, some are 

 liquid^ and some solid, and most are capable of being modified by suitable treat- 

 ment under various temperatures and pressures. The employment of petroleum in 

 the arts is still extending rapidly. Used originally for illuminating purposes, it is 

 now employed as fuel for heating furnaces and steam-boilers ; as a working agent in 

 heat engines, valuable medicinal properties have been discovered ; and as a 

 lubricant it stands unrivalled. 



As an illuminant, even in this country, it is, to a large extent, superseding 

 every other in private houses, and even in public lamps, because it gives a cheaper 

 and more brilliant light than ordinary gas, and leaves the consumer free from tha 

 tyranny of great and privileged companies. 



As fuel it is especially convenient, cleanly, and economical. Stored in tanks of suit- 

 able construction, it is sprayed into the furnace without labour and without creating 

 dust and dirt ; and it is especially convenient in locomotive and marine work on 

 account of the rapidity, ease, and cleanliness with which it can be run into the 

 tender or into the oil-bunkers of a ship. As a working agent in heat engines it is 

 employed in two ways. First as a vapour, generated from the liquid petroleum- 

 contained in a boiler, very much in the same way as the vapour of water is used 

 in an engine with surface condenser, the fuel for producing the vapour being also 

 petroleum. Very signal success has been obtained by Mr. Yarrow and others in. 

 this mode of using mineral oil, especially for marine purposes and for engines of 

 small power ; there seems to be no doubt that by using a highly volatile spirit in 

 the boiler a given amount of fuel will produce double the power obtainable by other 

 means, and at the same time the machinery will be lighter and will occupy less 

 space than if steam were the agent used. The other method is to inject a very fine 

 spray of hot oil, associated with the proper quantity of air, into the cylinder of an 

 ordinary gas-engine, and ignite it there by means of an electric spark or other suit- 

 able means. Attempts to use oil in this way date back many years, but it waa 

 not till 1888 that Messrs. Priestman Brothers exhibited at the Nottingham Show 

 of the Royal Agricultural Society an engine which worked successfully with 

 oil, the flashing point of which was higher than 76° F., and was therefore within 

 the category of safe oils. The engine exhibited was very like an ordinary Otto 

 gas-engine, and worked in exactly the same cycle. A pump at the side of 

 the engine forced air into a small receiver at a few pounds' pressure to the 

 square inch. The compressed air, acting by means of a small injector, carried 

 with it the oil in the form of fine spray, which issued into a jacketed chamber 

 heated by the exhaust, in which the oil was vaporised. The mingled air and oil 

 was thus raised to a temperature of about 300°, and was then drawn, with more 

 air, into the cylinder, where, after being compressed by the return stroke of the 

 piston, it was exploded by an electric spark, and at the end of the cycle the 

 products of combustion were discharged into the air after encircling the spray 

 chamber and parting with most of their heat to the injected oil. The results of 

 careful experiments made by Sir William Thomson and by myself on different 

 occasions were, that 1-73 lb. of petroleum were consumed per brake-horse power 

 per hour ; but the combustion was by no means perfect, for a sheet of paper held 

 over the exhaust pipe was soon thickly spattered with spots of oil. 



At the Windsor Show of the Eoyal Agricultural Society this year, Messrs. 

 Priestman again exhibited improved forms of their engine ; the consumption of oil 

 fell to 1'25 lb. per brake-horse power per hour, and a sheet of paper held over th& 

 exhaust remained perfectly clean. They also showed a portable engine of very 

 compact constiuction, and quite adapted to agricultural use ; the ordinary water 

 cart, which has, in any case, to attend a portable steam-engine, being adapted to 

 supply the water necessary to keep the working cylinder of the engine cool. 



It is hardly necessary to state that the use of petroleum for furnace purposes 

 of all kinds is increasing very rapidly, and the demand has naturally reacted on the 

 supply in promoting improved means of transport ; and Newcastle, again, has led 

 the van in this matter, for Sir William Armstrong, Mitchell & Co. have sent out 

 a fleet of steamers constructed to carry the oil in bulk with perfect safety, both as 



