54 



MAPLE-SAP SIRUP. 



the points of construction necessary to make a good sirup, but the 

 success of the run depends to a greater extent on the operator. Many 

 samples obtained from arch evaporators were as light colored and as 

 mild in flavor as those from the patent evaporator; but, as a general 

 rule, those from iron kettles were dark in color and strong. 



Summarizing the reports of the makers on this subject, the following 

 data were obtained for the individual States : 



Types of evaporators used in the various States. 



It is seen that the patent and the arch evaporators are used almost 

 without exception in all the States except Ohio, where quite a number 

 of iron kettles are still in use, the patent evaporators exceeding those 

 of the arch type, especially in Ohio, Pennsylvania, and Vermont. 



CLEANSING AND STRAINING. 



The sap as it comes from the trees in the first run is water white, 

 but toward the last, under ordinary conditions, it becomes greenish or 

 yellowish and apparently thicker. The percentage of sugar obtained 

 varies considerably in the case of the individual trees and with the 

 varying climatic conditions from year to year. The sap is almost a 

 pure sucrose solution, the percentage of nitrogenous matter being very 

 small. An average sucrose content of sap based on 225 determina- 

 tions is approximately 2.83 per cent, the average for total solids in 50 

 analyses being 3.9. Invert sugar is practically absent in the earlier 

 runs and present in the last runs in very small quantities, if at all. 

 Starch has never been found in the sap. The ash varies considerably; 

 an average given by Wiley based on 22 samples is 0.146 per cent. a 



When the sap is boiled, the nitrogenous matter tends to coagulate, 

 forming a scum on the surface of the boiling liquid, which must be 

 continuously skimmed off in order to obtain a clear sirup. It is noted, 

 when boiling maple sirup, that upon every addition of fresh sap there 

 is a violent ebullition of gas which throws the sediment to the top, and 

 quite a number of makers add it in small quantities with that end in 



U. S. Dept. Agr., Bureau of Chemistry Bui. 5, p. 210. 



