113 Jjxperimcrits on the Preparation of Sugar. 



According to Stahlhamuier's e.\-pcriinents *, eight quarts 

 of the juice of the common white birch belula alba, drawn 

 off in the fpring, gave a hnall quantity of fyrup, weaker 

 than that obtained from the maple, but fuperior to the 

 common brown fyrup. We are told, on the other hand, 

 by Kalm f, that a great deal of fugar is prepared from the 

 iuice of the black American birch Befula nigra carp'inifolia, 

 called alfo the fiigar-birch, but that this fugar is not alto- 

 gether fo fweet as the maple fugar. By the kindnefs of 

 Count Von Veltheim, at Harbke, I was enabled to obtain a 

 fufficient quantity of the juice of both thefe kinds of birch, 

 with which I maJe the following experiments : 



The trunks of fifty white birches, of from eight to ten 

 inches in diameter, being pierced in the month of April, 

 which is the moft favourable period, gave in the courfe of 

 four days 140 Berlin quarts of fap, which by infpiflation 

 produced two and a half pounds of brown fyrup, which had 

 an unpleafiuit tallc, and from which no cryftallifable fugar 

 could be obtained. 



On the other hand, ten trunks of the black birch which 

 had been tapped, gave in the courfe of ten days fifty quarts 

 of fap, w hich produced by infpiflation one pound and a half 

 of verv good fvrup ; wliich, however, was far inferior to that 

 obtained from the maple, though it was better than common 

 fvrup, and therefore I am induced to believe that Stahlham- 

 mer for his experiments muft have employed the black birch. 

 In the courfe of four months a confiderable portion of fugar 

 had crvftallifed from the juice of this birch. It is therefore 

 proved that real fugar may be obtained from the fap of the 

 black birch, but inferior in quality to that of the maple- tree, 

 and much more expenfive. 



8. Experiments iv'ith the White Beet Beta cicla alba. 



The late INIargraf made various experiments, above fifty* 

 vears ago, with feveral kinds of beet-root, in order to try 

 how far it was podible to procure fugar from them, and 

 according to his own account he fucceeded in obtaining from 



^ 'tranfnEi'iom of ibe SwrJ'Jh Acadinij '4 Sciences, Vol. XXXV. p. 335. 

 ' + /f.;</ Vol. Xlil. p. i;i. 



the 



