PLAMELESS COMBUSTION — ELLIS. 651 



whicJi, while evaporating 20 pounds of water per square foot of 

 heating surface, transmits upward of 90 per cent of the net heat of 

 combustion of the gas to the water, and which, if need be, can be 

 forced to a 50 per cent higher " duty" with only a slight drop in 

 efficiency, will stand unrivaled as a steam raiser. Moreover, in the 

 case of a large boiler, of say 100 tubes, " elasticity '■ ma}'' be conferred 

 by arranging the tubes in groups, so that they may be fired up or com- 

 pletely shut oif, group by group, successively, in correspondence with 

 variations in the load. 



The Skininygrove boiler has proved almost completely automatic 

 in its working, according to the statement of the manager of this 

 plant, who says, also : " The boiler has been off for the inspection of 

 the tubes, which prove to be clean and free from scale, a fact which 

 I attribute to highly rapid ebullition. During the length of time 

 the boiler has been at work we have had no trouble with priming, the 

 steam having been at all times perfectly dry. The average tempera- 

 lure of the waste gases leaving the plant has been from 78 to 80° C, 

 which is ample proof of the boiler's efficiency." 



Experiments to determine the value of this type of steam generator 

 as a waste-heat boiler show important economies. Work on oil-fired 

 boilers has also been carried out with satisfactory results. 



V. THE MELTING OF EASILY FUSIBLE METALS AND ALLOTS. 



It will be readily understood that the principle embodied in the 

 boiler is capable of great extension. Thus, for example, it can be 

 applied to (1) the preliminary concentration of dilute solutions and 

 the heating of liquids generally; (2) the heating of large volumes of 

 air; and (3) the melting of easily fusible metals and alloys. 



I will here refer briefly to some experiments on the fusion of metals. 

 Prof. Bone's attention was first drawn to this subject by experts of 

 one of the London gas companies, who represented that there would 

 be a large field of usefulness for the process in melting type metal for 

 large newspapers, which require for their machines a continuous sup- 

 ply of molten type metal. Plate 1, figure 3, represents an iron tank, 

 efficiently lagged and filled to the top with molten lead at a tempera- 

 lure of, say, 50° above its melting point. In the molten bath is fixed 

 an iron tube, 2 or 3 feet long and 3 inches in internal diameter. The 

 tube is packed (like one of the boiler tubes) with a suitable granular 

 refractory material, and there are suitable arrangements for the in- 

 troduction of the explosive mixture of gas and air which is to be 

 burned in the tube. When once the device is started up, it can be 

 worked continuously for days together. Solid lead is continuously 

 fed into the apparatus, and the molten metal is allowed to rim over 

 through the spout indicated in the diagram. Experiments have been 

 carried out with tanks holding up to 8 tons or more of molten metal. 



