THE PEODUCTION OF MAPLE SIRUP AND SUGAR. 37 



a high temperature, it is necessary to take the temperature at the 

 same time that the hydrometer is read. Subtract 60 from the num- 

 ber of degrees Fahrenheit of the heated sirup (this being the normal 

 temperature) and multiply the difference by 0.0265. This figure 

 (which is the temperature correction expressed in degrees Baume) is 

 added to the Baume reading of the hot sirup and the result is the 

 Baume reading of the cooled sirup. For example, a heated sirup 

 shows a reading of 80 at a temperature of 215 F. Then 



215-60=155 

 155X0.0265=4.1 

 30+4.10=34.1 



The cooled sirup would read 34.1 or by above table have about 38 

 per rent water. 



CANNING AND STORAGE. 



After the sirup is strained or settled, it is ready for canning. 

 Makers vary as to whether it should be canned hot or cold. Some 

 claim that canning hot tends to induce crystallization. It is certain 

 that when canned hot in sterile cans (steamed or washed in boiling 

 water) there is practically no danger from fermentation. This 

 can not be said of canning cold, although the sirup made one season 

 is generally sold before the beginning of the next season. When 

 made on a large scale, maple sirup is often run direct from the 

 evaporators into barrels and so shipped, but by far the greatest 

 number of sirup makers sell in quart, half-gallon, or gallon tin cans. 

 These cans are generally square, with a screw cap. When being 

 filled they are tipped slightly and then lifted by the upper edges and 

 filled even with the screw top, which is then fastened tight with a 

 wrench. This method applies to canning hot or warm sirup. When 

 the cans are being filled in cold weather and with cold sirup, it is 

 well to hold the can so that the sides are a little compressed and then 

 fill to the top and screw the lid on. By this means no air enters and 

 Avhen the sides are released the can being not quite full allows for 

 increase in volume when placed in a warmer room, without danger 

 of breaking. Fancy maple sirup is often put up in glass and, when 

 carefully canned will keep from one season to another without sour- 

 ing or bursting the jar. It is best to store sirup at an even, cold 

 temperature. Temperatures around freezing, however, should not 

 be used, as this tends to crystallization. 



CRYSTALLIZATION. 



Crystallization results from making a supersaturated solution of 

 a substance in a liquid. In the case of sirups the sucrose becomes 

 concentrated to a point at which it is no longer soluble in the water 

 present, and hence it crystallizes out. Maple sap, being a dilute solu- 

 tion of sucrose, in fact about 90 to 95 per cent of the solids in the 

 sap being this sugar, when concentrated soon reaches a point where 

 the sucrose will be supersaturated, and hence on cooling will start 

 to crystallize out. 



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