MULTIPLE EFFECTS. 361 



Crete fur some central factory or refiuery was worthy of careful con- 

 sideration by those who are unable to enter upon the expense of a 

 sugar house, since this concrete may be kept a long time, can be 

 shipped without loss, and worked for sugar when convenient. Its 

 market value would, of course, be largely dependent upon its content 

 of sugar ; but it could easily be worked over for syrup. By thus sim- 

 plifying the necessary work upon the farm, in the preparation of a 

 marketable article, it offers unusual facilities to those entering upon 

 this new industry with little experience and limited capital. In all the 

 methods thus far described for the removal of water from the saccha- 

 rine juices and the separation of the sugar, heat has been always the 

 agent employed ; but, to the chemist and the physicist, cold presents 

 itself as an agent well calculated to accomplish the same result, and 

 possessing certain great advantages in its em.ployment. 



Already this agent has long been considered as practically available, 

 and numerous experiments have been made to render it effective ; but 

 thus far no practical results appear to have been realized. 



One pound of water at 70° F. loses 38° in passing to the freezing 

 point, and in the act of freezing must part Avith 140° more of heat; 

 or, in other words, to freeze one pound of water at 70° F. requires the 

 removal of heat enough to raise 178 pounds of water one degree. 



On the other hand, one pound of water at 70° F, requires 142° of 

 heat to raise it to the boiling point ; and, to convert it into steam, re- 

 quires an additional 966°. 6 of heat; or, in other words, to convert one 

 pound of water at 70° F. into steam at 212° F. requires as much heat 

 as would suffice to raise 1,106.6 pounds of Avater one degree in tem- 

 perature. 



It appears, therefore, that the relative energy required to freeze or 

 boil Avater at 70° F. is as 178 is to 1,108.6, or as 1 to 6.23. In cA^ap- 

 oration, the energy developed in the combustion of AA'ood or coal, for 

 example, is applied directly, and, although, through radiation, conduc- 

 tion, and the various imperfections of the furnace, much of the energy 

 is lost — so far as effective Avork is concerned, such loss may be reduced 

 almost to its minimum ; but, in the several transformations necessary 

 to apply the energy developed by burning coal, through steam boilers, 

 engines, pumps, and so forth, to the freezing of Avater, the inevitable 

 loss seems to more than counteract the apparent ad\"antage the latter 

 operation has over the former. 



One pound of coal will evaporate about nine pounds of boiling 

 water, equal to 7.85 pounds of Avater at 70° F.; and it is claimed that 

 one pound of water maybe frozen by the combustion of three pounds of 

 coal under the boilers of the refrigerating apparatus. But, despite this 



