On the Sap of the Rose Tree. 149. 



I should not have considered the foregoing of sufficient im- 

 portance to communicate, if tliere had not been some circum- 

 stances, relative to the collecting of the sap, which, inde- 

 pendently, may be thought interesting, and which, perhaps, 

 may justify my wish to see this inserted in the Journal of 

 Science and the Arta, 



The tree which supplied the sap in question is the Rosa 

 ruhiflora, growing in a garden at Hammersmith. July 29th, it 

 was deprived of its branches by sawing off its head, leaving 

 a stem 3J feet high, and 2J inches in diameter. I was in- 

 formed the sap began to flow almost immediately after decapi- 

 tation. I did not see it until the following day, when the exu- 

 dation of the sap was so profuse, that I collected an ounce 

 measure of it in forty minutes. The temperature of the air at 

 the time was 67°. The saw-cut was made inclined to the 

 horizon ; hence the fluid accumulated at the lowest part of 

 the section, and I occasioned it to drop into a suspended phial 

 bottle, by a piece of twine fastened to the tree in such a man- 

 ner as to act the part of a conductor. 



The " bleeding" continued uninterruptedly, a few hours 

 more than a week; during this period I procured 31 ounces, 

 or nearly a quart ; this, together with that which escaped be- 

 fore my attention was directed to it, and the loss by evapora- 

 tion, probably exceeded three pints. The discharge diminished 

 in quantity from the time 1 first observed it. The tree is now 

 living, and vigorously protruding young shoots. 



Having at my disposal an abundance of sap, I repeated the 

 analysis upon six ounces collected on the fourth day, but in- 

 stead of obtaining from it corresponding products, it furnished, 

 by evaporation, scarcely one grain of residuum, consisting of 

 about 0.25 grains of oxalate of irnmnrMt. a trace of acetate of 

 lime, the remainder being gum. ^ 



A third quantity = 6 ounces of the last portions collected, 

 was also examined : in this trial the solid matter was quite equal 

 to the last, but it differed materially in constitution, for nothing 

 could be separated ; it was entirely gum. 



Some of the sap had been reserved, and by keeping, even 

 three or four days, it is found to generate acid, its presence 

 being detected by litmus paper ; therefore, in all similar cases, 



