from indigenous Plants. 339 



The clarified fluid afforded by evaporation three pounds of a fyrup {lightly four, but not 

 difagreeable. It was again difiblved in lime-water, for the purpofe of depriving it of its dif- 

 engaged acid, and lime-water was fuccefllvely added, until the ufual re-agents indicated no 

 figns of acidity. The fluid was then again clarified with whites of eggs, and a fecond time 

 evaporated. )^y this means I obtained a very pleafant fyrup, but could not fucceed in produc- 

 inga cryflallizable fugar. It mufl: alfo be obferved that it would not be poffible to prepare 

 this fyrup in a profitable way, as Jong as the hogfhead of good wine-muft can be fold /for 

 fiftecQ dollars. 



g. Experiments made with the Juice of the black and.white Birch, with the inteniim of 



manufafiuring Sug.ir. 



Opinions have hitherto been greatly divided, whether fugar can be obtained from the 

 juice of birch-trees. Many affirm, but others deny it. This induced me to apply to ex- 

 periment for a decifion. According to Stalbommer's * obfervations, eight kannen \ of the 

 liquor dravyn in the fpring from the common white birch (betula alba) yield five and a half 

 Itop of a fyrup, which is faid to be weaker than that from the maple, but fliU better than 

 the common brown fyrup. On the contrary, according to Kalm's experience |, the North 

 American black birch (betula nigra carpinifoUa), which is alfo called fugar-birch, yields 

 much fugar, but not fo fweet as that from the maple. By the particular kindnefs of Count 

 Veltheim at Harbke, 1 'received a fufficient quantity of juice from bothfpecies of birch 

 which ferved for the following experiments. 



Fifty trees of the white birch, from eight to ten inches diameter, being tapped in the 

 month of April, in which this tree flows the beft, yielded, in four days, 140 Berlin quarts of 

 liquor ; which, by evaporation, produced ^'\h of a brown fyrup, of an unpleafant taflie, from 

 which no cryftallized fugar could be obtained. 



On the other hand, ten of the black birch trees being bored, afforded 50 quarts of juice in 

 four days ; from which when evaporated a pound and a half of a very good and ferviceable 

 fyrup was obtained. Though much inferior to that from the maple, it was neverthelefe 

 fuperior to the common ; and from this I am inclined to conclude, that Stdlhammer em- 

 ployed the black birch for his experiments. Duiing the period of four months, a confidera.- 

 ble portion of fugar has cryftaiiized from the liquor of the black birch ; it is therefore 

 proved, that real fugar may be prepared from the black birch ; which, however, would be 

 too cxpenfive, and with refpect to quality is far excelled by .the maple-fugar. 



* Tranfaflions of the Royal Swedifli Academy of Sciences, Vol. XXXV. page 335, feqq. 



f A Stucdijb kanrtd is of 132 Parifian cubic inches capacity; a _/?«/^ is its half, ot 66 inches ditto. 



Tranfljtor. 



X Tranfoftioin of the Royal Swtdiflx Academy, Vol. Xill. page 151, feqq. 



[To bt concluded in gur next. J 

 1 '' Obfervations 



