196 Mr. J. Napieh on Incrustations in Steam Boilers. 



the diiSculty in applying this salt is the regulating the quantity ; the 

 practice has been to throw in from time to time large quantities of soda, 

 which formed an alkaline ley in the boiler, and as soda passes freely off 

 with steam, this practice has frustrated the object, as the alkaline steam 

 hurt the stuffings, &c., of the engine. In a boiler treated thus, without 

 any attention being paid afterwards, there was found at the bottom, 

 after several months, the soda having been only thrown in once or twice 

 at first and left to work a perpetual cure, a hard incrusted studge half an 

 inch thick, composed of 100 parts : — 



This had lain exposed for sevei'al weeks to the air before being analyzed. 



Soap has been tried, and is found to decompose both the carbonates 

 and sulphates of lime. The tallow of the soap being rendered insoluble, 

 or rather combines with some of the lime, and forms an earthy soap, which 

 sometimes floats upon the sm-face of the water, forming a solid scum, 

 preventing the escape of the steam, or causing priming, and when com- 

 bined with much lime, it occasionally deposits and forms a very nasty 

 crust upon the boiler. Means could be adopted to carry off the scum and 

 recover the tallow, but its action being dependent upon the alkali it 

 contains, it wUl be better to use the alkali pure. When soap is used in 

 larger quantity than is necessary to decompose the salts in the water, 

 priming is sure to follow. 



Soda and gallic acid, and tannin prenite of soda, is recently patented. 

 Besides these, which have some chemical principle in them, I will name 

 over the following as a proof of the haphazard system of remedies, not 

 only suggested, but tried and advocated, and even patented : — Sawdust, 

 potatoes, potato skins, sugar, glucose, mixture of coal tar and linseed, 

 Castile soap and plumbago, ground dyewoods, gum, catechu, oak bark, 

 and green vegetable matters. Such is a list of what has been tried. 



The effect which incrustations have upon boilers is matter of dispute. 

 Some have boldly declared that they are not detrimental, either to the 

 boUer or its economical production of steam ; but there having been 

 such a general feeling after a remedy, indicated by the list just given, 

 is, I think, a practical answer to the economical question. The difficulty 

 experienced in keeping up the steam when the boiler was covered over 

 with a crust, has evidently led men to try anything in hopes of removing 

 the evil ; and I know that the burning of holes in boilers are often 



