236 Intelligence and Miscellaneous Articles. 



the substance and the brown colour which it acquires by calcination 

 indicate that it is richer in iron than is the case with talc. 



Independently of the minerals which have been described, proto- 

 gine, as observed by MM. Dufrenoy and E. de Beaumont, may 

 accidentally contain liornblende, sphene, iron pyrites, garnets and 

 serpentine. 



Some veins contain fluor spar, oligiste iron and sulpliuret of 

 molybdenum, &c. In I'Oisan there are albite, rutile,anatase,brookite, 

 &c. ; lastly, there are found in veins which appear to be contem- 

 poraneous with the rock, and usually formed of quartz, epidote 

 and the variety of chlorite, to which M. G. Rose has given the 

 name of ripidolite ; it is also found in the paste of protogine. — Ann. 

 de Chtm.et de Phys., Janvier 1849. 



^•^' EXAMINATION OF MADDER. BY M. DEBUS. 



til 21V 



In order to isolate the different colourmg matters of Zealand 

 madder, the author employs the following process : the root is ex- 

 hausted by boiling water, and the decoction is boiled with excess of 

 hydrate of lead. The colouring matters form with this oxide in- 

 soluble compounds of a reddish brown colour. The deposit is to 

 be separated, washed, and decomposed with dilute sulphuric acid 

 and heat. The colouring matters, which are slightly soluble in 

 water, separate with the sulphate of lead. The precipitate is to be 

 boiled in alcohol, which dissolves the greater part of the colouring 

 matters. They may be separated into two groups by agitating the 

 alcoholic solution with calcined oxide of zinc. Some of them pre- 

 cipitate in combination with the oxide of zinc, while others remain 

 in solution. 



Tiie author has hitherto examined only the first group, that is to 

 say, the colouring matters combined with the oxide of zinc. They 

 are purified by decomposing them with weak sulphuric acid, and 

 dissolving the precipitated colouring matter in aether ; the solution 

 obtained is again heated with oxide of zinc. The zinc compound, 

 heated with dilute sulphuric acid, leaves as a residue a mixture of 

 two colouring matters, both soluble in a boiling solution of alum, 

 one of which precipitates on cooling and the other remains in solu- 

 tion ; the first constitutes what the author calls lizaric acid; this 

 substance is obtained in a state of purity by boiling it with a little 

 dilute hydrochloric acid, to free it from the alumina which it retains, 

 and by repeated solution in boiling alcohol. 



The second colouring matter, which remains in solution in the 

 aluminous liquors, may be precipitated by sulphuric acid. The 

 separation is not completed in less than twenty-four hours ; the pre- 

 cipitate, exhausted by hot dilute hydrochloric acid, which removes 

 a little alumina, is afterwards dissolved in 150 to 200 times its 

 weight of boiling alcohol. In two or three hours long red needles 

 separate, which constitute what M. Debus calls alizaric acid. 



Lizarie Acid. — It crystallizes from its alcoholic solution in long 



