CREAMERY BUTTER MAKING 175 



10. Do not fail to examine the pressure gauge fre- 

 quently. 



11. It is good policy to have two means of feeding a 

 boiler. The pump or injector may get out of order and 

 cause delay and danger. 



12. Feed pumps and injectors need frequent cleaning 

 to keep them in good working order. 



13. Look out for air leaks. If air is admitted any- 

 where except through the grates serious waste may re- 

 sult. Such leaks are to be looked for in broken doors and 

 poor brick work. 



14. Flues should be cleaned often, especially if soft 

 coal is burned. This will prevent over heating of metal, 

 at the same time save fuel. 



15. Do not allow filth 'to accumulate around the boiler 

 or boiler room. 



1 6. Keep all the bright work about the boiler "shiny." 



17. Do not fail to empty the boiler every week or two 

 and refill with fresh water. 



1 8. Have your steam gauge tested at least twice a 

 year. 



BOILER INCRUSTATION. 



In all boilers after a period of use, there is deposited 

 upon the parts below the water level a scale or sediment 

 known as boiler incrustation. 



Cause of Scale. The formation of scale is due to 

 the impurities contained in the feed water. When impure 

 water is fed into the boiler the impurity first manifests 

 itself in the form of scum on top of the boiling water. 

 The heavier particles of the scum slowly unite and sink 

 to the bottom where they first appear as mud. By con- 

 tinued exposure to high temperature, this mud gradually 



