DISCUSSION OF MANUFACTUKING DATA. 55 



view. In small amounts this addition may not darken the sirup, but 

 in large quantities it does, as the time of boiling is lengthened, and the 

 constant thickening and diluting of the liquid destroys some sugar and 

 organic matter. The coagulum or scum contains, besides the nitrog- 

 enous matter, some mineral salts, mostly lime salts and suspended 

 dirt. On further evaporation or boiling, the mineral salts of the sap 

 become concentrated, and when the point of supersaturation is 

 reached these are partly deposited on the sides and bottom of the 

 evaporator, the remainder being held in suspension in the thick sirup. 

 This deposit, known as "sugar sand," "niter, " "silica, " etc., consists 

 for the most part of a malate of lime. Two analyses of crude niter 

 are given, one of an Indiana sample and the other of a sample col- 

 lected during this investigation. 



Two analyses of crude niter. 



a Twelfth Ann. Report of the Indiana Agricultural Experiment Station, 1899, p. 74. 



The quantity of deposit varies in different years, and also there is 

 usually a larger deposit late in the year than at the beginning of the 

 season. The different methods and means to which makers resort for 

 removing this suspended matter and scale, and thus cleansing the 

 sirup, are discussed in the following paragraphs. 



Among the makers visited opinions differed widely as to the need of 

 adding cleansing substances. As has been mentioned, some of the 

 impurities are coagulable by heat and rise to the surface while the sap 

 is boiling, and the excess of ash is precipitated on concentration, 

 either being deposited on the boiling apparatus or remaining in sus- 

 pension. The large makers simply filter the sirup through felt or 

 cloth bags before boiling is completed and again after it is brought to 

 the desired density and is still hot, which removes the finely divided 

 sediment. At a large percentage of the camps, however, some cleans- 

 ing agent, such as milk or white of egg, was used. In most of the 

 cases where these were used the thin sirup was taken from the evap- 

 orators when weighing about 8 or 10 pounds to the gallon, cooled, and 

 the cleansing substances added, after which the thin sirup was boiled 

 down in small lots to the desired consistency. 



