llO On the Sap of the Vine. [Fkb. 



It did not affect litin\is or turmeric papers in their natural 5tate!«, 

 nor the former when it was faintly reddened by acetic acid. Specific 

 gravity not sensibly different fronj that of water. 



1. Potash. — A solution of pure potash changed it to a beautiful 

 reddish copper colour, and caused after some little time a flaky 

 precipitate of the same colour, leaving the fluid nearly colourless 

 and transparent. This precipitate was not redissolved by excess of 

 potash even when heat was applied, but the application of heat 

 changed it to a deepish brown colour. Acetic acid added in slight 

 excess readily redissolved this precipitate. 



2. Ammoniu. — The same phenomena followed the use of this 

 alkali as of potash above-mentioned. Acetic acid also as readily 

 redissolved the precipitate occasioned by it as by potash. 



3. Muriatic Acid produced no apparent change. After the 

 addition of this acid, ammonia was added in excess, when precisely 

 the same sort of precipitate as that above-mentioned was observed. 



4. Oxymuriatic Acid produced no apparent change. 



5. Muriate of Barytes. — No apparent change. 



6. Oxalate of Ammonia produced a very sensible white preci- 

 pitate. 



7. Prussiate of Potash caused a very slight whitish precipitate. _ 



8. Hijdro-suLphuret oj Potash. — A slight dark brown flaky preci- 

 cipitate. 



9. Nitrate of Silver. — A slight flaky precipitate, which soon 

 became of a purple hue. 



10. Oxz/wzmoife 0/' Mpjt?/?-^.— No apparent change. 



11. Sulacetate 0/ Lead. — A copious yellowish-white precipitate. 



12. Infusion of Galls. — No apparent change. 



13. Gelatine.— t<o apparent change. 



Four hundred and sixty grains of the sap were evaporated in a 

 glass capsule on a sand-bath. During the evaporation air bubble? 

 collected on the sides and bottom of the vessel. The fluid became 

 slightly opake, and towards the end of the operation brown flocculi 

 precipitated. There was left only ^ gr. of solid matter (= -044 

 per cent.), about half of which was carbonate of lime, the rest a 

 peculiar vegetable matter. This peculiar vegetable matter was not 

 soluble in alcohol, and therefore did not agree in this respect with 

 the ill-defined class of substances called extracts or extractives. 

 Both it, however, as well as the lime, were evidently held in solu- 

 tion by some volatile acid or acids. One of these acids was doubt- 

 less the carbonic. There were also traces of the acetic acid, and 

 likewise of an alkali (potash ?), since the glass capsule on exposure 

 to the air became sensibly moist. The quantities, however, of the 

 last two were extremely minute. 



Every thing connected with vegetable physiology is exceedingly 

 obsure. The opinion,* however, appears to be correct, which 



<■ • Darwin's Phytologia, p. 2S, &t. Mr. Kiiight, in Pliilosopbical Tiansae- 

 tioDs, 1S03, p. 70, &c. 



