Micro-organisms of Maple Sap 



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"The materials used are (i) pure glycerin and (j) a cara- 

 mel solution, which is prepared as follows: 



Heat 6 grams of pure sugar to 212 C. for one-half hour 

 in a flat bottomed aluminum dish and dissolve the caramel 

 formed in boiling water, evaporate to a small volume, and make 

 up to 200 cc. with glycerin. The oven for caramelizing the sugar 

 (fig. 1) is constructed as follows: 



A and A' are heavy sheets of asbestos board iS cm. (7 

 inches) square, A' being perforated near one aV^c by a hole 



for a cork supporting the thermometer 

 d: b is a sheet-iron cylinder 15 cm. (6 

 inches ) in diameter ; ; c is a tin can 9 cm. 

 (3/^> inches) in diameter, which is filled 

 with paraffin to within 1 cm. ( l / 2 inch) 

 of the top. This can rests on the pipe- 

 stem triangle e. The bath or oven is 

 supported on a tripod and is heated by 

 two burners. One burner is so ad- 

 justed as to keep the bath at 212 C. 



Bring the temperature of the oven up 

 to 212 C, using both burners. Then re- 

 Pig, j. Apparatus for prepa- move the asbestos cover carrying the 



tion of standard caramel. J ° 



thermometer and place 6 grams of sugar in a flat-bottomed 

 aluminum dish 7 cm. (2^4 inches) in diameter and 1.5 cm. (^ 

 inch) deep, and put it in the can containing the paraffin. Replace 

 the cover at once and as soon as the temperature reaches 208 C. 

 turn out one burner and keep the bath at 212 C. by carefully ad- 

 justing the other one. At the expiration of thirty minutes from 

 the time the sugar was placed in the bath, dissolve in boiling wa 

 ter, and make up as described. The aluminum dish should not be 

 less than 1.5 cm. (^ inch) deep, since the sugar melts before 

 caramelizing and runs to one side of the dish, which, if too shal- 

 low, will tilt, fill with paraffin, and sink. 



With the ingredients thus prepared, the scale of colors is 

 made up by mixing as indicated in the following table :" 



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