56 ROUGH-AND-TUMBLE ENGINEERING 



satisfactory results from your engine, you must keep a 

 clean boiler, and to keep it clean requires care and 

 labor. If you neglect it you may expect trouble. If 

 you blow out your boiler hot, or if the mud and slush 

 bakes on the tubes, a scale is formed, which decreases 

 the boiler's evaporating capacity. You must, therefore, 

 in order to make a sufficient amount of steam, increase 

 the amount of fuel used, which is of itself a source of 

 expense, to say nothing of the extra labor and the 

 danger of causing the tubes to leak from the increased 

 heat produced in the firebox in order to make steam 

 sufficient to do the work. 



You must not expect economy of fuel, and at the same 

 time keep a dirty boiler. Don't condemn a boiler be- 

 cause of hard firing until you know it is clean, and don't 

 say it is clean when it can be shown to be half full of 

 mud. 



SCALE 



Advertisements say that certain compounds will pre- 

 vent scale in boilers, and I think they tell the truth, as 

 far as they go; but they don't say what the result may 

 be on iron. I will not advise the use of any of these 

 preparations, for several reasons. In the first place, cer- 

 tain chemicals will successfully remove the scale formed 

 bv water charged with bicarbonate of lime, and have no 

 effect on water charged with sulphate of lime. Some 



