ROt BERING 57 



ll of bark summac, logwood, etc., arc sufficient 



to remove the s. charged with magnesia 



irbonate of lime. :ijurious to the iron 



to the tannic acid with which they arc charged. 



gar, rotten apples, slop, etc., owing to their con- 



ng acetic acid, will remove scale, but this is even 



more injurious to the iron than the barks. Alkalies of 



ch as soda, will be found good in v. 

 containing sulphate of lime, by converting it into a car- 

 bonate and thereby forming a soft scale, which is easily 

 washed out, but these have their objections, for, when 

 used to excess, they cause foaming. 



Petroleum is not a bad thing in water where sul- 

 phate of lime prevails but you should use only the re- 

 fined, as crude oil sometimes helps to form a very in- 

 jurious scale. 



Carbonate of soda and corn-starch have been recom- 

 mended as a scale preventative, and I am inclined to 

 think they are as good as anything, but as we are out in 

 the country most of the time, I can tell you of a simple 

 little thins that will answer the same purpose, and can 

 ith little trouble. Every Monday morn- 

 dump a hatful of potatoes into your boiler, and 

 S.itr h the boiler out, as I have already 



the fall's run is over there will not 

 be much scale in the boiler. 



