THE PRODUCTION OF MAPLE SIRUP AND SUGAR. 31 



It runs only when the atmospheric conditions are favorable ; as a 

 rule the run is stronger during the day than at night and quite 

 often in the middle of the day than in morning or evening. As the 

 changes of weather occur the sap stops, to start again when the right- 

 conditions are present, so there may D a run of sap for a day or two 

 and a lapse of a few days before another. During a season there 

 may be as few as two or three runs or as many as ten or twelve. 

 Freezing weather will stop the run, as will excessive wind, too bright 

 sun, or a warm snap. 



At the beginning of the season the sap is water white, clear, and 

 transparent and has a sweet taste, but as the season advances the 

 color and physical appearance change. It usually becomes cloudy 

 and yellowish and gets a peculiar odor. The composition of the 

 sap varies considerably, depending upon the season and the tree. 

 There is anywhere from 1 to 5 per cent of solids in the sap, of 

 which about 95 to 97 per cent are sucrose or ordinary sugar, so the 

 sugar content varies anywhere from 1 to 4 per cent, with an average 

 of 2 per cent or possibly more. Besides sucrose, there is present 

 some nitrogenous matter and some mineral matter. Reducing sugars 

 have never been found in normal sap by the author, although many 

 hundreds of samples have been examined. 



Containing as it does nitrogenous matter and also ash, the sap 

 is very susceptible to the growth of microorganisms, which are be- 

 lieved to cause the souring of sap. Edson 1 has done much work 

 along this line and show r s that the change in physical condition of 

 the sap toward the end of the season is due to a great extent to micro- 

 organisms. When the sap is running well the danger from them is 

 not great, but when the warm weather starts and the flow is inter- 

 mittent they become very active. Therefore the sap should be col- 

 lected each day and not be allowed to accumulate. It is necessary 

 also to keep the buckets and containers clean. After each run they 

 should be washed Avith warm water. This is of extreme importance 

 in obtaining a fine grade of sirup from the later runs. One of the 

 visible signs of sour sap is the mucous formation in the buckets. 

 When this is noted the buckets should be cleaned out thoroughly and 

 scalded. 



The tap holes as well as the buckets become infected. This infec- 

 tion increases more slowly in spouts with small openings than in 

 hollow tubes with large bore. The latter allow a drying out of the 

 wood tissue, which drying, together with the growth of micro- 

 organisms, slackens the flow of sap and causes what does flow to be 

 a wrong color. It is under these circumstances that reaming of the 

 tap holes is recommended, as this removes the dry contaminated 

 tissue. At the same time the spouts should be steamed out or fresh 

 ones inserted. This care in the sugar bush is necessary for a good 

 product. 



" Buddy sap " is the name applied to late runs of sap, especially 

 1hat running at about the time the buds in the trees start to open. 

 It is usually green in color or may be yellowish and has a peculiar 

 odor easily recognized. Sirup produced from this sap does not have 

 a good flavor and is always dark colored. 



1 Vermont Agr. Exper. Sta. Bui. 151 ; Bui. 167. 

 516 



