34 THE PBODUCTIOK OF MAPLE SIEUP AND SUGAR. 



centrated solution and also in the finished sirup. This makes the 

 sirup murky and less attractive in appearance. Settling removes a 

 large percentage of this suspended matter, and if the semisirup is 

 filtered through flannel a greater portion is removed. 



Other means recommended for removing this sediment are white 

 of egg, whole milk, and baking soda. These are added to the sirup 

 in the last pan and work by coagulating around the suspended mat- 

 ter and bringing it to the top or by liberation of a gas, causing foam 

 to appear. Then, by careful skimming, this is removed. When used 

 in quantities these settlers change the flavor of the sirup and, con- 

 trary to the general belief, do not render the sirup lighter in color. 

 Baking soda, added to the finishing sirup to make it foam and bring 

 the foreign material to the top, also tends to neutralize any acidity. 

 Its use is a very questionable practice, for if in any quantity it 

 darkens the sirup besides greatly changing the flavor. 



This cleansing can be accomplished by allowing the finished sirup 

 to settle or by pouring off the sirup from the evaporator through 

 felt or flannel into the cooling cans, and as a rule this will give as 

 light-colored sirup as when the clarifiers are used. Felt strainers 

 shaped like caps can be obtained. Such a strainer may be 10 inches 

 in diameter at the top and 14 inches deep. By suspending this in 

 the neck of a large milk can and turning the edges the hot sirup 

 readily filters through. By having cocks arranged in the settling 

 can, the clear sirup can be drawn off from the top cock after the 

 sirup has been allowed to stand, and then be drawn from the lower 

 ones in turn, stopping when the sediment is reached. Double thick- 

 ness of heavy flannel serves as a fair substitute for the felt. The 

 sirup should" be filtered hot, as it is very difficult to get it to pass 

 through when cold. 



DETERMINATION OF FINISHING POINT. 



Commercial maple sirup weighs 11 pounds to the United States 

 gallon. Such a sirup will have 65 per cent solids or 35 per cent- 

 w y ater. A sirup made thinner than this that is, containing more 

 water will soon sour, and one made much thicker near 12 pounds 

 to the gallon will tend to crystallize. The maker has to determine 

 the density of his product. This is often accomplished in a crude 

 way by noting the bubbles as they break on the surface of the 

 boiling sirup or by removing some in a spoon and watching how it 

 pours. A more satisfactory way is either by means' of a ther- 

 mometer to determine the boiling point or with a Baume hydrom- 

 eter spindle to determine its density. 



By thermometer: The boiling point of a liquid is influenced by its 

 concentration and also by the altitude. Water at sea level boils at 

 212 F., but for every 500 feet above sea level, roughly speaking, 

 the boiling point is lowered 1. Therefore, at an altitude 

 of 2,000 feet the boiling point of water is 208 F. The Vermont 

 Agricultural Experiment Station has found that a maple sirup 

 boiling at 219 F. weighs 11 pounds to the gallon, or is at stand- 

 ard density. This figure, however, changes a little, depending on 

 the run of the sap. A first run will often boil at 217 or 218 F. 



516 



