152 THE SCIENTIFIC PAPERS OF 



Experiments on this mode of evaporating have been so successful 

 that a vacuum pan is now being constructed as above described, 

 capable of evaporating 50 cubic feet of water per hour, in which it 

 is estimated that a vacuum of from 18 to 20 inches of mercury 

 will be maintained. The form of pan shown in Fig. 16 is the 

 simplest arrangement in which the steam jet exhauster can be 

 applied for the purpose ; but the exhauster can with equal advan- 

 tage be applied in those cases where vacuum pans are worked 

 on the systems known as double and triple effect. It has been 

 successfully employed to exhaust a vacuum pan having a condenser 

 placed high enough above the ground to discharge by gravitation 

 against the vacuum the condensing water in which the vapour 

 from the pan was condensed ; there was thus left only the air and 

 a very small quantity of vapour to be removed by the exhauster, 

 which in this case was a very small one, not using sufficient steam 

 to produce evaporation. 



The steam-jet exhauster is further expected, on account of its 

 cheapness and simplicity, to prove very useful in the colonies for 

 draining the molasses from the sugar, by exhausting the air from 

 below the perforated bottom of a strainer containing the undrained 

 sugar, the pressure of the atmosphere then driving the syrup or 

 molasses through the sugar and perforated bottom. By this means 

 the crude and imperfect mode of draining by gravitation, and also 

 the more elaborate but costly and troublesome centrifugal strainers, 

 can be superseded with advantage. 



BLOWER FOE GAS-PRODUCERS. A further application of the 

 improved steam jet is to gas-producers for heating purposes. The 

 author has had occasion to make numerous applications of the 

 steam jet arranged as a blower for accelerating the distillation of 

 fuel in his gas-producers, as shown in Figs. 17 and 18, Plate 30. 



The blower B is built into the side wall of the producer, and the 

 combined current of air and steam delivered by it issues through 

 an opening A into the space C underneath the fire-grate, which is 

 closed by doors 1). The small proportion of steam that enters 

 together with the air is just sufficient to assist beneficially in the 

 production of the combustible gas, inasmuch as in passing through 

 the incandescent fuel the steam becomes converted into hydrogen 

 and carbonic oxide. The steam is admitted to the blower through 

 the branch pipe E from the main steam pipe F, which supplies a 



