STATE HORTICULTURAL SOCIETY. 179 



acting as a barrier to the escape of the steam holds the latter un- 

 der compression and until with increasing temperature and cor- 

 responding force it escapes from its confinement. 



In this phenomena the dispersion and distribution of the molten 

 iron is as complete as is that of steam in the exploding steam 

 boiler. In either case the principle or element of motion is the 

 open link between cause and effect. The condition determining 

 whether the result shall be one of safety or disaster. In the ex- 

 ample of the molten iron this resultant is too impetuous and in- 

 fractions for any and all practical purposes, and its employment 

 is never attempted by operators of good judgment. They prefer 

 to let the liquid return to its normal temperature unmolested 

 and to allow the heat it contained to go to waste rather than at- 

 tempt to utilize by compounding it with water. 



The practicability of employing the compound — heat and 

 water — for the purpose of evaporating liquids lies, first, in the 

 fact that the resulting element, steam, has for equal volumes a 

 weight of only the 1-1,700 part of the water from which it was 

 generated or about 35-1,000 pound to the cubic foot under light 

 pressure, and 2-10 pound under working pressure, and therefore 

 yields readily to the impulse of motion and can be conducted 

 from the steam boiler in pipes to any point with very little ex- 

 penditure of power or loss of motion save that required to over- 

 come friction — and, second, the perfect adaptation of steam to 

 evaporating purposes is by. reason of the great rapidity with 

 which it resolves into its original elements the moment it is 

 brought in contact with a body of comparatively low tempera- 

 ture. 



Under a boiler pressure of 70 pounds to the square inch the 

 temperature of steam is about 315°, and as 300 volumes of this 

 steam contains suflBcient heat to convert one volume of water 

 into steam having a temperature of 212°, it constitutes at once a 

 most powerful and efficient agent for conveying and imparting 

 heat to any body of liquid, the volume of which we wish to re- 

 duce by evaporating a large per cent of the water it may con- 

 tain. It is powerful because of the slight affinity existing be- 

 tween the component elements at a temperature above 212°, 

 the extra abundant or latent heat being imparted instantaneously 

 to surrounding objects. It is efficient because of its extreme 

 mobility, moving quickly in any direction where it may escape 

 confinement and find a body to which it can transfer its burden 

 of heat, and lastly, but by no means of least importance, it is 



