THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



SEPTEMBER 1852. 



XXIV. On some Salts and Products of Decomposition of Pyro- 

 meconic Acid, By Mr. James F. Brown*. 



nnniS acid was discovered by Sertuerner, and long viewed as 

 A sublimed meconic acid, till Robiquet in 1833 obtained the 

 meconic acid from which it is produced, and showed that the 

 acid existing in opium differed in its properties from the sub- 

 limed acid : he also prepared and analysed its lead salt, from 

 which he deduced the formula PbO, C^'^ H^ 0\ Liebig has ob- 

 served that its composition is the same as that of pja-omucic 

 acid, and thought it probable these acids might prove identical. 

 This assertion, however, has been refuted by Dr. Stenhouse iu 

 his paper on the subject, to some of the details in which I shall 

 have occasion to refer. 



The pyromeconic acid employed in the following experiments 

 was obtained by distilling, at a temperature of about 500° and 

 600° F., the impure meconic acid got by treating the crudie 

 meconate of lime twice with hydrochloric acid, which, though 

 much coloured, answered sufficiently well. For the purification 

 of the acid, which when first sublimed is in the form of an oily 

 scmifuscd mass, Stenhouse recommends pressure between folds 

 of filtei-ing paper, redistillation, and frequent crystallization from 

 boiling alcohol. I found, however, that simple pressure, and 

 sublimation at a comparatively low temperature in a cylindrical 

 glass vessel pronded with a number of diaphragms of filtering 

 paper, rendered the acid perfectly colourless, and pure enough 

 for the pnsparation of all its salts and products of decomposition. 



As thus obtained, it is in beautiful large transparent plates, of 

 ready solubility in water and alcohol, both hot and cold, from 



* Comiiuinicated l)y the Author, having been read before tlie Royal 

 Society of Edinburgh, March 1, 1852. 



PhiL May, S. 4. Vol. 4. No. 24. Sejit. 1852. M 



