Chemistry and Physics. 275 



wire in the tubes of oxygen, nitrogen, carbonic acid, carburetted by» 

 drogen, &c, than by that in the tube containing pure hydrogen. It 

 became necessary now to ascertain the cause of this peculiar phenom- 

 enon of hydrogen. It was found not be due to specific heat, nor to the 

 conducting powers of the gases. Convection did not explain the fact; 

 considerable difficulty was found upon examination if it was attempted 

 to refer it to the greater mobility of the particles of hydrogen gas, the 

 lightest known. It was found that this peculiar property also belonged, 

 but to a less extent, to all the compounds of hydrogen and carbon. 



A discussion followed, in which Dr. Williams, Col. York. Prof. Gra- 

 ham, and Mr. Hunt joined. — Prof. Graham mentioned the curious fact 

 observed by him in his researches on the diffusion of gases, that the 

 hydro-carbons move through tubes with great velocity, and that ether 

 vapor, which is four times the density of hydrogen, moves, notwith- 

 standing its weight, at four times the rate of other gases. It was 

 thought this would, perhaps, serve to indicate the path in which an ex- 

 planation might be looked for. — Mr. Hunt drew attention to the fact, 

 observed by Prof. Graham, that ether vapor had the power of prevent- 

 ing the combustion of phosphuretted hydrogen and of destroying the 

 luminosity of phosphorus, and thought the phenomenon observed by 

 Mr. Grove connected itself in some way with these curious properties 

 of the hydro-carbons. 



6. Report on Coloring Matters ; by Dr. E. Schunck, (Proc. Brit. 

 Assoc, Athen., No. 1086.) — Having referred to the six substances 

 which were discovered in the infusion of madder roots, and described 

 in the last Report, the author announces the discovery of a seventh. 

 The continued investigation of the subject has led to the conclusion, 

 that there is but one coloring matter in madder, i e., the Alizarin 

 and that the substance which was thought to be a coloring matter, viz. 

 Rubiacin, is not so. The seven substances found in the brown precip 

 itate from the madder infusion are Alizarin, Rubiacin, Alpha-resin 

 Beta- resin, Rubian, Pectic Acid and Oxydized Extractive. The exam 

 ination of the fluid was next made, and found to contain Xanthic acid 

 and madder yellow. It has also been proved that madder contains 

 sugar; — but as the process by which this is separated is somewhat te- 

 dious, we must refer chemists to the Report itself. It is known that 

 after madder has been employed for dyeing, it still contains coloring 

 waiter, and that the article garanceux is tna nu fact u red from this. By 

 treating this substance with boiling muriatic acid, it was found to con- 

 tains lime, magnesia, oxalate of lime, phosphate of lime, alumina, and 

 peroxyd of iron. After these salts were separated, boiling water ex- 

 tracted a large quantity of coloring matter which would dye mordanted 

 cl oth quite full, and of the same color as madder itself, thus showing 

 that it contains alizarin. Alizarin is found to be composed of 



Carbon, 56 ' 97 



419 



Hydrogen 

 Oxygen, 



38-81 



or, in fact, of carbonic acid and water. Alizaric acid is formed by 

 treating alizarin with concentrated per-salts of iron or nitric acid. The 

 salts of this acid are mostlv soluble. Alizarate of lime is prepared by 





