59 



to heavy sirup by hot air. The cano juice was boiled to a density of from 20 to 25 

 degrees Baume, according to the quality of the juice, and as was necessary to clarify 

 the juice, and only boiled as long as it was necessary to skim the boiling juice. It 

 was then dried, or evaporated by hot air, at a temperature of 130 to 140 degrees, until 

 it became dense sirup. It is probable that it would fcave been better to have had a 

 temperature of 140 to 180 degrees, which is the best temperature for evaporating fruit 

 by hot air, and which is the usual temperature in vacuum-pan boiling. In the cold- 

 air apparatus it was necessary to boil the juice until it had such density that air at 

 summer temperature would not act chemically upon the sirup or ferment it, and then 

 finish the evaporation by air at ordinary temperature. 



In the hot-air apparatus it was necessary to boil the juice only long enough to 

 clarify it, and then finish the evaporation by air heated above the point of chemical 

 action or fermentation. To illustrate this point : Ordinary sirup may be exposed to 

 air at summer temperature without change or fermentation, while a dilute sweet 

 liquid exposed to air at summer temperature would be chemically changed ; but a 

 dilute sweet liquid exposed to air heated to 150 degrees, which is the scalding-point, 

 would not ferment it would evaporate to sirup. 



This hot-air apparatus had 273 square feet of surface, inclosed in a box 3 by 2 feet 

 and 6 feet high. At a temperature of 140 degrees it evaporated ] pound of water 

 per hour from each square foot of surface that is, it evaporated 273 pounds of water 

 per hour at 140 degrees. A gallon of cane juice weighs 8.8 pounds. Reducing 7 gal- 

 lons of cane juice, or 61.6 pounds of juice, to 1 gallon of heavy sirup at sugar density 

 weighing 13 pounds to the gallon, requires the evaporation of 48.6 pounds of water 

 for each gallon of sirup. Where the evaporation from cane juice to heavy sirup is 

 entirely performed by hot air, the hot-air apparatus gives 5i gallons of sirup, weigh- 

 ing 13 pounds to the gallon, per hour, as the product of the evaporation from 273 

 square feet of surface in a current of air at 140 degrees. When cane juice is boiled 

 to a density of 20 to 25 degrees Baum6 in order to clarify it, and the hot-air apparatus 

 is only required to finish the evaporation, it produces from 10 to 15 gallons of heavy 

 sirup per hour, for the greater part of the evaporation has been performed by boiling. 



The hot-air apparatus above described is of a size and capacity suited to a two- 

 horse cane-mill. It would finish the semi-sirup produced by such a mill to heavy 

 sirup, using a temperature of 140 degrees instead of 240 degrees, which is required in 

 finishing heavy sirup by boiling. 



The principle of the air-evaporating apparatus is, that evaporation is as rapid from 

 large surfaces exposed to air at comparatively low temperature as from small surfaces 

 intensely heated, and that in evaporating dilute sweet liquids it is necessary to heat 

 the air above the point of chemical action upon the liquid. Solid substances have 

 large quantities of water removed from them by exposing large surfaces to the evapo- 

 rating action of the air. A bushel of apples weighing 50 pounds is reduced by hot 

 air to 6 pounds of perfect product. The same can be done with liquids under similar 

 conditions. As a result of these experiments we intend to build hot-air apparatus 

 large enough to reduce all our semi-sirup to sirup by hot air next season. 



If the question be asked, "Can the farmer profitably make his own 

 sugar ?" i. e., make sugar for his own use in a small way, I apprehend 

 that the answer should be much the same as would be given to the ques- 

 tion, U 0an the farmer profitably make his own woolen goods or his own 

 flour? " If, indeed, I have succeeded in the preceding pages in convey- 

 ing an adequate idea of what sugar-making is, I apprehend that my 

 readers will omit to ask the questions about manufacturing in a very 

 small way. 



The farmer who is so fortunate as to be near a sugar factory can do 

 much better than to erect and try to operate sugar machinery on a 



