62 BOILER TESTS. 



wetting of Cumberland bituminous coal secured an apprecia- 

 ble advantage. By adding 5 per cent of its weight of water, 

 the evaporation, based on the dry weight, was increased 3 per 

 cent. 



According to the results of tests No. 97 and No. 98, the loss 

 produced by banking a Cumberland coal fire was about 2 per 

 cent. 



The prevention of smoke was attained in an almost complete 

 manner in Boiler No. 30, burning Cumberland bituminous 

 coal, by the use of a sufficient quantity of air above the fuel 

 and of superheated steam below the grate. The general 

 economic result was, however, inferior to that obtained by 

 boilers in which the smoke is not suppressed. 



The indication of the calorimeter trials made in connection 

 with the tests, so far as they have been conducted, is that the 

 steam produced by the boilers which do not superheat is in 

 nearly a dry state. Horizontal tubular boilers Nos. 2, 9, 32 9 

 35, 36, 39, 42 and 45, gave steam containing respectively 0.6, 

 0.3, 2.2, 0.7, 0.5, 0.2, 0.5 and 0.3 per cent, of moisture, the 

 average being 0.7 percent. Water-tube boilers Nos. 65, 68, 

 70 and 71, gave respectively 0.6, 1.3, 0.4 and 0.5 per cent., 

 averaging 0.7 per cent. The Galloway boiler No. 50 gave 7 

 per cent., and the single boiler which was tested gave dry 

 steam. 



The remaining tests would be of greater value if the quality 

 of the steam had been obtained. It is not unreasonable to 

 apply the general results of a number of calorimeter tests on 

 a given type of boiler, to one of the same type where the 

 quality of the steam is not known, but it is somewhat unsatis- 

 factory when it is seen that boilers qf one type, the horizontal 

 type for example, give percentages of moisture varying from 

 0.2 to 2.2 per cent. The question naturally arises in a case 

 where a high evaporation is produced, whether it is not due in 

 a measure to the wet quality of the steam. This question 

 cannot be definitely answered unless a calorimeter trial is 

 made. In the absence of such a trial, however, there are some 

 external evidences which throw light upon the subject. If the 



