THE PRODUCTION OF MAPLE SIRUP AND SUGAR. 33 



pans. This mineral matter, commonly known as "sugar sand." 

 u niter," " silica," is mainly a malate of lime. Its removal will be 

 discussed under "Cleansing and straining." 



In concentrating any sugar juice there are a few fundamental 

 facts that should be known. Sugar in solution is easily broken up 

 by long boiling, and as the solution becomes more concentrated the 

 temjx'rature of boiling is raised and more decomposition takes place. 

 Then to retain the flavor of the thin juice in the resulting concen- 

 trated sirup, it must be evaporated as quickly and at as low a tempera- 

 ture as possible. The time consumed in evaporation can be regulated, 

 but the boiling temperature can not be changed except by boiling in 

 vacuo, which on a small scale or even on a rather large scale would 

 not be possible, as the price of installation of apparatus would be 

 prohibitive. 



When using iron kettles they should be charged and this charge 

 concentrated, the kettles being filled once or twice with fresh sap. 

 but a light-colored, good-flavored sirup will not be obtained by keep- 

 ing up the addition of fresh sap to the boiling kettle and only " sirup- 

 ing off " once or twice during the day. This concentrating, then 

 diluting, and then concentrating induces decomposition of the sugar 

 and organic matter and therefore blackens the sirup. It is difficult, 

 as stated before (p. 28), to obtain a fine, mild-flavored maple product 

 from concentrating in iron kettles. 



Iron pans may produce dark-colored sirup, as also may patent 

 evaporators if they are used to concentrate sap in the way the iron 

 kettles are used. 



The way to obtain good products with pans or patent evaporators, 

 provided the sap is not sour, is to concentrate in as thin a layer as 

 possible, drawing off the sirup as quickly as made. Where a large 

 single pan is used this is hardly possible," but one can put in an inch 

 or two of sap, boil, and add more, a little at a time, so as not to stop 

 boiling or materially change the density of the boiling liquid; then, 

 when this charge is concentrated, the sirup should be drawn off. 

 Care must be exercised not to allow the remaining sirup in the pan 

 to be burned. Where more than one pan is used the sap can be 

 placed in the one over the fire, skimmed, and partially concentrated, 

 then transferred to the next and further boiled, then ladled to the 

 others, the last pan being the finishing pan. As on& pan is emptied 

 the sap from the one in front is brought to it. This means allows 

 better skimming. In patent evaporators the sap and partially con- 

 centrated sirup, flow through siphons from one compartment to the 

 other, thus doing away with the use of a ladle. 



To produce the highest quality, best-flavored sirup, the sap or 

 semiconcent rated sap should not be deeper than 1 to 1J inches in 

 the evaporator at any one time. This produces a quick evaporation 

 with the least quantity of decomposition. 



CLEANSING AND STRAINING. 



During concentration, as stated before, the mineral matter of the 

 sap becomes more or less insoluble and precipitates out, a large por- 

 tion incrusting the pan, and more or less floating in the semicon- 



516 



