138 



THE ILLINOIS FAEMEK. 



May 



weight of boiling water to steam without raising 

 its sensible temperature, as is required to raise the 

 same weight of water from the freezing point to 

 the boiling point, that is, 990® , or, in round num- 

 bers, as usually stated, 1000 ® . 



Without standing committed to any of the the- 

 ories upon the nature of heat, let it be abstract mo- 

 tion, or an intangible essence, electic or eclectic, as 

 may be di termined by those who think themselves 

 competent to decide, for our purposes it is allow- 

 able and very convenient to regard it as a sub- 

 Btance-matter, and to conisder an atom of heat to 

 be as indistiuctible as an atom of granite. We 

 have found that the steam of a given quntity of 

 water takes up as much heat as would raise the 

 temperature of five and a half times the weight of 

 water from the freezing point to the boiling point ; 

 and now, as heat is indistructable, we are prepared 

 to understand that if this steam be condensed or 

 returiud ngtiin to water, it must give out precisely 

 the amount of heat it had previously absorbed, and 

 it is obvious that if properly applied the heat thus 

 given out in the process of condensation mav be 

 employed in healing or in boiling and evaporating 

 other wat 'r always remembering that absolute and 

 unvarying equivalents are required in every case. 

 Th.it is, a pound of steam will, upon being con- 

 densed, give out heat enough to raise the tempera- 

 ture of five and a half pounds of waf^r from the 

 freezing point to the boiling point, or to convert 

 anotlier pound of boiling water entirely to steam. 

 It can never do any more, and never less. The 

 only place for management and economy in the 

 operation is in the means of utalizing the initial 

 heat, preventing waste by radiation, and in prop- 

 erly applying the heat set free by condensation. 



These d:;ta require to be observed and kept in 

 view, a^ they will by and by assist in determining 

 the oft repetcd question as to the relative economy 

 of steam and direct fire evaporation. 



But in employing the heat of steam for evaporat- 

 ing it is common to generate in the steam boiler 

 under something more than atmospheric pressure ; 

 say under a pressure of from one to six or eight 

 atmospheres. By this means a great quantity of 

 heat is contained in the same compass or volume, 

 although in the same weight of steam the amount 

 ofh"at remains the same. For example : a cubic 

 inch of water eonverted to steam under atmospheric 

 pressure, will expand to 1696 inches. If this be 

 subjected to a pressure of 14.6 pounds to the square 

 inch it will be compressed to 848 inches, and its 

 sensible temperature will be elevated from 212 ® 

 to 251 ° , resulting from a transfer of a portion of 

 heat from a latent to sensible state. The sum or 

 absolute quantity of haat remains the same it will 

 melt no more ice and communicate no more heat 

 to a certain volume of cold water than before it 

 was compressed and its heat apparently increased. 

 If it be further compressed by the weight of anoth- 

 er atmosphere its volume will be reduced to 565 

 inches, and its sensible or apparent heat raised to 

 272 ° , another atmosphere will reduce the volume 

 to 424 inches, and raise the sensible temperature 

 to 294 ° , and so on, the volume of steam diminish- 

 ing and the apparent temperature increasing at 

 each stage, but the absolute amount of heat remain- 

 ing the same. We thus have this apparent para- 

 dox, that a pound of steam, under a pressure of 

 fifty atmospheres, and having a temperature of 



more than 500 ° Fahrenheit, has taken up and 

 contains no more heat and will melt no more ice 

 than the same weight of steam generated and ap- 

 plied at atmospheric pressure corresponding with 

 212 ° . This fact is interesting, and at the same 

 time important, in a practical point of view as we 

 shall hereafter show. 



From the foregoing it will appear that the steam 

 generated in a regular steam boiler with a certain 

 amount of fuel, if applied in the ordinary way to 

 the evaporation of cane juice, will, upon being con- 

 densed, give out as much heat and evaporate pre- 

 cisely the same amount of water as wou/d 6e va- 

 porized by the same quantity of fuel applied direct- 

 ly to the juice pan. It is moreover to be mention- 

 ed that the water of condensation which leaves the 

 steam pipe in the operation is the exact mesure of 

 the water expelled in the form of vapor from the 

 surface of the pan. There are, however, a few cir- 

 cumstances of minor importance to be considered. 

 On the one hand, a regular steam boiler, having a 

 large heating surface, may be supposed to absorb 

 more of the heat of combustion than is utaJized by 

 juice pans, as ordinarily arranged. This is an ad- 

 vantage or saving effected by the steam process. 

 On the other hand, allowance must be made for the 

 loss of heat by radiation from a large boiler surface, 

 and from the steam pipes leading fi om boiler to 

 pan ; also for the heat expended in raising the wa- 

 ter in the boiler, and all the feed water, from what 

 may have been the temperature of the /brmer at 

 each time of starting, and of the latter when pump- 

 ed into the boiler, to the boiling point ; for it must 

 be remembered that effective results are not pro- 

 duced until the temperature of the generating ap- 

 paratus is raised to boiling temerature. These con- 

 stitute a drawback or a deduction to be made from 

 the steam process. On the whole it may be safely 

 assumed that tne gain and loss growing out of these 

 minor circumstances are about equalized, and that, 

 practically as well as theoretically, there is no 

 economy in either plan over the other. Each mav 

 be more economical than the orher accordingly a's 

 the absolute conditions upon which economy de- 

 pends are more perfectly complied with. — Clark'* 

 Sorgo Journal. 



We give place to the above carefully prepared 

 article, for the purpose of enabling our readers to 

 make their calculation in regard to the size of their 

 pans and mills as compared to their crops. 



A large bredth of cane will be planted k'" Spring 

 and farmers need make preparation to hayti t . rk- 

 ed up, when this can be done on shares, in some 

 cases this will not be the case and you will be ob 

 liged to put up your own fixtures. Ed. 



White Beans. — ^This crop ought to be more gen- 

 erally cultivated by farmers- The small variety or 

 army bean, is in great demand for our troops, and 

 is worth at least $2.50 per bushel at wholesale. 

 They should be sown in drills about 2^ feet apart, 

 at the rate of at least a bushel to an acre. Sow 

 from the 10th. to the 25th. May. Fifty bushels to 

 the acre are known to have been raised. They 

 are a safe crop to grow between the rows in a 

 young apple orchard, ank always leave the ground 

 in fine condition. Let every farmer resolve to have 

 at least one acre this season. — Working Farmer. 



