THE PRODUCTION OF MAPLE SIRUP AXD SUGAR. 29 



a flue and a brick or metal chimney extending through (he roof. 

 In the front grate ba.rs may be provided and an excavation made for 

 an ash pit. 



In the arch and patent evaporators it is well to build the arch 

 during good weather and allow it to set, as when built hurriedly 

 before the season or in bad weather it is likely to crumble and 

 break away. It is of extreme importance to see that the top 

 layer of the two sides are of equal height so that the pan will set 

 level: a slight slant of an inch in 16 feet in the level of the length 

 of the arch is of value, as it gives the sirup a tendency to run toward 

 the back where the final concentration takes place. 



The pans are made to fit the arch and are not over (> inches deep. 

 The edges may be turned over a stout wire to give rigidity and 

 strength, and 'should be fitted with handles so that they can be 

 readily removed from the fire. The arch can be supplied with a 

 regular stove front containing a fire door and ash door or be fitted 

 as in the cut with a piece of sheet metal. The former gives a better 

 and closer fitting front and allows a better control of draft. 



Patent evaporators are simply improvements over the arch evapo- 

 rators, but the fundamental principle is the same. The arch is gen- 

 erally metal, lined with fire brick. The pans fit the form much more 

 closely to allow a better play of heat without loss, and often have 

 corrugated bottoms to present a greater surface to the fire for quicker 

 evaporation. The pans are also partitioned off to give a zigzag 

 course to the sap. 



Some forms have an apparatus at the side which automatically 

 keeps a constant level of sap in the boiling parts and can be set and 

 regulated to keep an even depth of boiling sap. The finished sirup 

 can then be drawn off continuously. 



The iron arch with its dampers allows the best results from the 

 fire, which are hard to obtain in an ordinary arch built of masonry. 

 Such patent evaporators can be obtained in sizes from 2 by 7 feet 

 up to 6 by 24 feet. The larger sizes are capable of taking care of 

 greater quantities of sap. In general, with this style of evaporator 

 with corrugated bottom, 1 square foot of bottom is capable of con- 

 centrating about 2 gallons of sap per hour that is, a pan 3 by 8 

 feet, or 24 square feet, will evaporate about 40 to 50 gallons of sap 

 per hour and one 4 by 16 feet, or 64 square feet, will evaporate about 

 115 to 130 gallons per hour. Some makers have found that about 

 10 square feet of boiling surface are necessary for every 100 buckets 

 set. That is, a camp of 500 trees would need an evaporator of 50 

 square feet. In figuring capacity, it is well to take the minimum 

 figures rather than the average or maximum figures. 



STJGARING-OFF APPARATUS. 



Where maple sugar is made as a side issue or in very small quan- 

 tities, it is customary to make the extra concentration in pots over 

 the kitchen stove, but where made on a larger scale, special appa- 

 ratus is used. Figure 10 shows a homemade suga ring-off pan. These 

 pans are much shorter than the evaporators and very much deeper, 

 generally from 2 to 2^ feet wide by 3 to 6 feet long and from 12 to 



516* 



