DR. KANE ON THE CHEMICAL HISTORY OF ARCHIL AND LITMUS. 313 
Second. If a solution of persulphuret of calcium or of sulphuret of barium be 
mixed with a solution of a blue litmus liquor, no loss of colour results. Some blue 
azolitmate of lime or of baryta is deposited, but no decolorization occurs. On the 
addition of an acid, there is an immediate disengagement of sulphuretted hydrogen, 
and the blue colour at once disappears. 
Third. If azolitmate of lead be treated by a current of sulphuretted hydrogen, it is 
converted into a black powder undistinguishable in colour from sulphuret of lead. This 
powder may be boiled in water without being decomposed, but by protracted boiling 
or washing it yields azolitmine, though very sparingly. When treated with solution 
of potash or ammonia, a deep blue liquor is immediately obtained, and sulphuret of 
lead remains behind. It is, therefore, a positive chemical compound of azolitmine 
and sulphuret of lead corresponding to that containing the oxide of that metal ; thus 
C 18 H 10 N O 10 + 3 Pb O is similar to C 18 H 10 N O 10 -f- 3 Pb S. 
This black substance cannot be azolitmine precipitated and mixed mechanically 
with sulphuret of lead, for water of sulphuretted hydrogen dissolves azolitmine 
better than pure water. In this compound also the colour of the azolitmine is com- 
pletely lost, as when it combines with sulphuretted hydrogen in solution. 
Fourth. If in place of azolitmine the betaorceine in combination with oxide of 
lead be acted upon by sulphuretted hydrogen, the evidence is perfectly decisive that 
the black substance produced is a compound of orceine and sulphuret of lead. It 
may be boiled in alcohol without yielding up a trace of colouring matter, but when 
treated with water of ammonia it is immediately decomposed, the usual rich purple 
liquor being produced. It is remarkable, however, that an excess of sulphuretted 
hydrogen has, on the betaorceinate of lead, the same effect which ammonia would 
have, that is, to produce a more basic salt. Thus if the betaorceinate of lead be dif- 
fused through water and treated with sulphuretted hydrogen, a considerable quantity 
of betaorceine will be found in the colourless liquor combined with sulphuretted 
hydrogen, the reaction being 
2(C 18 H 10 NO 8 .3PbO) + 7SH = C 18 H 10 NO 8 .6PbS + C 18 H 10 NO 8 .HS. 
Fifth. A point of considerable interest as involved in the action of sulphuretted 
hydrogen on these colouring matters, is to ascertain whether in the decolorized 
form there might not be a certain quantity of the oxygen of the substance replaced 
by sulphur. Thus, that from C 18 H 10 N O 10 + S H there might be formed C 18 H 10 
N 0 9 S + H O. That this does not take place, is fully shown by the constitution of 
the compounds with the metallic sulphurets. On destroying, by means of nitric acid, 
the compounds of betaorceine and of azolitmine with sulphuret of lead, I found that 
neutral sulphate of lead was formed, and that the liquors contained no trace of sul- 
phuric acid. The sulphur was, therefore, only in sufficient quantity to convert the 
lead into sulphuret, and hence the oxygen of the organic substance is not in any 
degree replaced by sulphur. 
mdcccxl. 2 s 
