192 Mb. J. Napieb on Incrustations in Steam Boilers. 



dies are sought after and tried : and hence nostrums of all kinds, like 

 quack medicines, have been poured indiscriminately into the steam 

 boiler, as a certain cure, without the slightest reference to the nature 

 of the evil further than the general fact, that there was a cake or crust 

 upon the boiler or tubes. 



Sometimes the chemist has been called in to prescribe, and various 

 cures have been suggested, some of which are certainly in themselves 

 effective in preventing certain kinds of incrustation ; but from subse- 

 quent reactions, which were not foreseen, the cure in many cases became 

 worse than the disease. I will, in the first place, refer briefly to the 

 cause of incrustations, their nature and composition, and then to some 

 of the remedies that have been tried and suggested, pointing out what 

 I consider the best and most economical. 



If rain or distilled water alone be used for boilers, there would be no 

 incrustation, because such water contains no salt in solution. But river 

 and spring water always contain matters in solution, and these yield 

 incrustation. The ordinary ingredients held in solution, in river and 

 spring waters, are bicarbonate and sulphate of lime, iron, and magnesia, 

 with salts of potash and soda. In some water the sulphates prevail, 

 and in others the carbonate, depending altogether upon the soil or rock 

 over and through which the water flows. Rivers at a distance from 

 towns may be verj'- regular in composition, but near manufacturing 

 towns the water will vary very much in quaUty, owing to the various 

 soluble refuse matters let into the river. The quantity of the different 

 salts generally found in water which can be held in solution, when the 

 water is cold, and when boiling, is as follows, reckoning ounces of salt 

 per gallon of water : — 



I may remark, that some of these salts are more soluble in a solution 

 of other salts than they are in pure water. As, for example, sulphate 



