128 Dr. Stenhouse on the 



On the other hand, an infusion of gall-nuts throws down 

 cyanol in brownish-yellow flakes, which are soluble in hot 

 water and alcohol. 



[To be continued.] 



XXII. On the Products of the Distillation of Meconic Acid. 

 By John Stenhouse, P/t.Z).* 



WHEN either meconic or komenic acids are subjected to 

 distillation at a temperature varying from 510° to 550° 

 F., they yield pyromeconic acid, which passes into the receiver 

 partly as an oily liquid and partly as a crystalline sublimate. 

 Towards the close of the distillation a few crystals of another 

 acid, to which we shall subsequently advert, appear on the sides 

 and neck of the retort. 



Pyromeconic acid, as first obtained, is very impure, being 

 contaminated with empyreumatic oil, and some acetic acid; it 

 may be easily freed from the greater portion of these impuri- 

 ties by pressing it between folds of blotting-paper, and cau- 

 tiously re-distilling it at a comparatively low temperature; the 

 pyromeconic acid is then nearly colourless, and if again pressed 

 and repeatedly crystallized out of spirits of wine, in which it 

 is very soluble, may be easily obtained in large colourless 

 prisms. The acid should be crystallized from rather concen- 

 trated solutions and quickly dried, as the crystals become co- 

 loured if exposed to the air in a moist state for any length of 

 time. A portion of pyromeconic acid thus purified was dried 

 at 212° F. and analysed in the usual way. 



I. 0*381 gramme of substance gave 0*7435 of carbonic acid 

 and 0-123 of water. 



II. 0*404 gramme gave 0*783 of carbonic acid and 0*128 

 of water. 



III. 0*323 gramme gave 0629 of carbonic acid and 0*1105 

 of water. 



At. Calculated numbers. Percent. 

 10 Carbon = 764350= 54*046 

 4 Hydrogen = 49918= 3*530 

 6 Oxygen = 600*000 = 42424 

 100*00 10000 10000 1414268 100000 



These analyses give the formula C 10 H 3 O 6 + HO for the 

 hydrated acid, which agrees precisely with Robiquet's deter- 

 mination. 



Pyromeconic acid, when pure, hardly, if at all, reddens lit- 

 mus paper, and if a single drop of any of the alkalies is added 

 to its solution, it is immediately rendered alkaline. 



* Communicated by the Chemical Society; having been read November 

 7, 1843. 



