Steel Boilers

Some interesting experimenta have beeu made m Prussia with steel .team boiler, an account of which lias beeu pubüslied in Dinyler s Polytetluiic Journal. A steel boiler 01 the eg-eud sbape, four feet in diameter and tfirty feot iu ieugth, without fiut's, was tned It had a steam drum two fret iu diameter aud two teei iu heigbt, and the plates were oue-fourth of au Deh in thicknes. Beside il tlu-re was ulaced anotiier boiler, similar iu every respect exoepuug Uiat the plates were of iron 0.41-i of au inch in thickness. The gtearu boiler was tested by hydraulic pressure up tu 195 pouuds ou the iuch, without leakage, and botli the iron and steel boilers were worked under a pressure of 65 ponnds on the inoli for about one year aud a halt. Durmg this period the steei boiler generated tweuty-tive per cent more steauj than the iron one, and when thcy were thoroughly exaiir.ned aiter eighteen mouths' prajtical working, there was less seale in the steel than in the iron boilor. The foruier evapórate 11-66 oubic feet of water per bour ; the iron boiler 9.37 eubie feet. The quantity of coa! cousumed was on an average 2,706 pounds for the steel one in twelve hours, and 2,972 pounds for the iron boiler. The plates of the steel boiler over the firo were found to be uniujured, while those of the ron one wero about worn out. In Prussia several worn out plates of iron boilers have lately been replaced with steel, which, it is stated, lasts four times as long. As steel is twice as strong as iron, thinner plates of theformer may be employed for boilers, and more perfect riveting eau be seeured. A greater quantitj of steum can also be generated in the stoel boiler on account of its thin platea, aud thus rauch fuel may be economized.