OXALIC ACID IN RHUBARB. gg^ 



fjor inconvenienced by distance; for during the winter you 



may distil at Paris herbs salted long before in places the 



most remote from the capital. 



According to some, distilled waters thus|obtained are more Applicable to 



fragrant, and at the same time yield more essential oil. z^*^^^' u^T*' 

 o ' J ter of which 



Lastly I would add, that this mode of salting may be ap- will not keep, 

 plied to some very useful purposes. For instance, if it be 

 true, that the waters of some herbs will not keep the j'-ear 

 round, though distilled with the utjnoft care ;~these herbs., 

 if properly salted, will keep ; so that they may be distilled 

 when v/anted, and their water employed while in full pos- 

 session of its medical virtues. 



XIV. 



On the Existence of Oxalic Acid in the Leaves and Stalks of 

 the Rheum palmatum, or true Rhubarb ; bi/ Mr. B. L*o 



At is well known, that Scheele observed the existence of Oxalate of 



oxalate of lime in the root of rhubarb; but 1 am not ac- I'™! '" '^''" 



J . , , , . barb root. 



quamted with any person s having examined the juice, ftalks, 



and leaves, of the rheum palmatum, Mr. Vogel and my- 

 self, surprised at the quantity of free acid in this plant, 

 endeavoured to ascertain its nature. 



We first pounded the leaves and stalks in a wooden mor- Juice of the 

 tar, expressed the juice, and filtered it. leavei&staik?. 



It was clear, with a slight yellowish tinge. Its smell was Its properties. 

 weak, and somewhat like that of melilot. Its taste was evi- 

 dently acid, and it reddened the paper and infusion of lit- 

 mus very powerfully. 



The pure alkalis and their carbonates changed its colour Examined 

 to a deep brown, without occasioning any precipitate. ^^^^ drfferent 



The oxalate of ammonia produced no change in it. 



With limewater a whitish precipitate was formed, insolu- 

 ble in water, but soluble in acids. 



The muriate of lime likewise occasions a very copious 

 white precipitate, insoluble in water, but soluble in nitric 

 acid. 



* Annales d«Chimie» yoI. LXVIT, p, 91. 



The 



