THE 



PHILOSOPHICAL MAGAZINE 



AND 



ANNALS OF PHILOSOPHY. 



[NEW SERIES.] 



MAR C H 1831 



XXVII. On the Volatility of Oxalic Acid. By EDWARD TUR- 

 NER, M.D. F.R.S. L., # E. 9 Sec. G.S. Professor of Chemistry 

 in the University of "London*. 



r P'HE object of this notice is to communicate a few facts 

 respecting the volatility of oxalic acid. It is stated in 

 chemical works, that when this acid is exposed to the destruc- 

 tive distillation, part escapes decomposition and is sublimed, 

 being deposited as a white sublimate in the neck of the retort; 

 but whether this appearance is owing to real volatility, or is an 

 instance of that spurious kind of sublimation, exemplified in 

 the ascent of boracic acid along with aqueous vapour, and in 

 the removal of fused chloride of silver when a current of hy- 

 drogen gas is passing rather rapidly over its surface, does not 

 seem to have been fully determined. Oxalic acid, in conse- 

 quence, is not generally regarded as volatile, except at a tem- 

 perature sufficiently high for producing its decomposition. 



Having been accidentally led to investigate this point, I 

 found that oxalic acid may be sublimed at a very moderate 

 temperature, even so low as 212Fahr., without undergoing any 

 chemical change, except that the common crystals lose two- 

 thirds, corresponding to two equivalents, of their water of 

 crystallization. When 63 parts of the common crystals are 

 placed in a water-bath, efflorescence rapidly ensues, and 

 17*31 parts, somewhat less than two equivalents, of water are 

 expelled. If the effloresced mass is then removed from the 

 fire and exposed to the air, it speedily recovers from the at- 

 mosphere precisely the quantity of water which it had lost ; 

 but if it be still kept in the water-bath, the surface of the acid, 



* Communicated by the Author. 

 N. S. Vol. 9. No. 51. Mar. 1831. Y instead 



