1864.] in which Nitrogen is substituted for Hydrogen, 383 



alcohol differs from the previous one, and takes place according to the 

 equation 



Sulphate of tetrazodiphenyl. Alcohol. Diphenyl. Aldehyde. 



The diphenyl which results from this reaction is identical with the com- 

 pounds obtained by Fittig from bromobenzol. A comparative examination 

 of the two demonstrates this most unmistakeably. 



The transformation which sulphate of tetrazodiphenyl undergoes when 

 it is heated with a small quantity of strong sulphuric acid is likewise of 

 great interest. Two new sulpho-acids are formed, which I shall call 

 tetra- and tri-sulphodiphenylenic acid. The following equation explains 

 their formation in the most natural manner : — 



Tetrazodi- Tetrasulphodiphe- 

 phenyl. nylenic acid. 



G,, H, N, + 3SH, Q,=€,, H„ S3 H, 0,, + N,. 



V ; 



Trisulphodiphenylic acid. 



The separation of these two acids is based upon the unequal solubiHty 

 of their barium-salts. The process is, however, somewhat complicated, 

 and I therefore abstain from describing it. Both acids are capable of com- 

 bining with bases in various proportions. Tetrasulphodiphenylenic acid is 

 octobasic. The lead-salt crystaUizes in beautiful needles, and has the com- 

 position Hy, Pbg Ojg. Trisulphodiphenylenic acid appears to be hexa- 

 basic. I have as yet only prepared the former acid in a free state. It 

 crystallizes in white needles, which are readily soluble in water and alcohol. 



Tetrabromide of the Tetrazodiphenyl, O^^HgN^, 2HBr, Br^. 



This compound forms crystals of an orange colour with curved faces. 

 On heating with alcohol, it splits up according to the equation 



N„ H, Br, = Br^-f N, + Br,. 

 Tetrabromide. Bromodiphenyl. 



Bromodiphenyl crystaUizes from alcohol and ether (in which it is rather 

 difficultly soluble) in beautiful prisms which fuse at lg4° C. This sub- 

 stance can be distilled without undergoing decomposition. Bromodiphenyl 

 has also been obtained by Fittig (according to a private communication) by 

 the action of bromine upon diphenyl. 



The platinum-salt of tetrazodiphenyl, N^, Cl^ (PtCl2)2, forms 



small yellow plates, which furnish, when heated with carbonate of sodium, 

 chlorodiphenyl closely resembling the analogous bromine-compound. 



