lY. CHEMICS. 



1. Salines, 



Embracing the various alkaline salts, manufactured from 

 common salt and potash, together with water, and the more 

 important acids. 



1. Water and Solution. — The character of a water, as to its 

 fitness or unfitness for manufacturing purposes, is deserving of 

 some attention. Thus, water derived from coal-mines is often 

 so highly charged with free sulphuric acid, derived from the 

 oxidation of pyrites in the coal, as to corrode a steam-boiler 

 dangerously and rapidly ; and, again, some waters deposit a 

 sediment when boiled, which incrusts the interior of a boiler, 

 and thus acts injuriously. The deposit generally consists of 

 sulphate of lime, and many methods have been contrived to 

 prevent its formation. One method is, to add salammoniac to 

 the water which supplies the boiler, whereby the pan-stone is 

 not formed. 



Incrustations in boilers may be prevented in many cases by 

 precipitating lime from solution in the water, kept in a tank, 

 previously to its being run into boilers, and either allowing the 

 precipitate to settle or running it through a filter of earth and 

 sand. 



Testing Water. — Dupasquier proposes to test water for an 

 unusual amount of organic matter, by a few drops of chloride 

 of gold solution. The usual quantity does not alter the yellow 

 tint imparted by the gold even by boiling, but when more than 

 usual, it passes through a brownish color to bluish and violet 

 (Comptes Rendus, Avril, 1847). To test for bicarbonate of 

 lime, he adds a few drops of a tincture of campeachy-wood, 

 ■which changes to violet from the presence of this salt, or of 



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