STEAM 



aperture into the spout n. The fecula now falls upon a second web of fine wire- 

 cloth, and leaves upon it merely some fragments of the parenchyma or cellular 

 matter of the potato, to be turned out by a side opening in the spout, . The sifting 



1894 



or straining of the starch likewise takes place through the sides of the cylinder, which 

 consists also of wire-cloth ; it is collected into a wooden spout, m, and is thence con- 

 ducted into the tubs o o, to be deposited and washed, p is a mitre-toothed wheel- 

 work, placed on the driving-shaft, and gives motion to the upright axis or spindle, 

 q q, which turns the brushes, i, i. 



STARCHING AND STEAM-DRYING APPARATUS. For a description of these pro- 

 cesses, and of the machinery for accomplishing them, see BLEACHING and CALICO- 

 PRINTING. 



STATUARY PORCELAIN. See POTTERY. 



STEA1W is water in its vaporiform state. The varied and important application* 

 of steam as a mechanical power would appear to render a consideration of its laws of 

 the utmost importance. The circumstance that our spinning and weaving machinery, 

 our pumping engines, our ships, our carriages, our hammers, our lathes, and our 

 presses, are all moved by this power, seems to demand a full consideration of steam 

 in a work devoted to Arts, Manufactures, and Mines, into each division of which it 

 enters as an important element. But the limits assigned to the en tire work renders it 

 impossible to treat in any way commensurate with its importance this great mechanical 

 power. It is, therefore, thought advisable to confine attention to a few general and 

 well-established principles only. For especial information on the subject, the reader is 

 referred to W. J. Macquorn-Rankine's ' Manual of the Steam-Engine ; ' Tredgold ' On 

 the Steam-Engine ; ' De Pambour ' On the Theory of the Steam-Engine,' and ' On the 

 Locomotive Engine ; ' Arago Sur les Machines a Vapeur ; Eegnault's papers in the 

 Memoircs and Comptes Eendus of the Academy of Sciences, &c. 



Steam is a chemical compound of oxygen and hydrogen, in the proportion of 8 

 parts by weight of oxygen, to 1 of hydrogen. Its composition by volume is such, that 

 the quantity of steam which, if it were a perfect gas, would occupy 1 cubic foot at a 

 given pressure and temperature, contains as much oxygen as would, if uncombined, 

 occupy half a cubic foot, and as much hydrogen as would, if uncombined, occupy 1 

 cubic foot, at the same pressure and temperature ; BO that steam, if it were a perfect 

 gas, would occupy two-thirds the space which its constituents occupy when uncom- 



