176 Mr. Perkin on Mauve or Aniline-Purple. [1864. 



tion be thrown up into a tube containing carbonic acid over mercury, the 

 carbonic acid will quickly be absorbed, the solution in the mean time pass- 

 ing from its normal violet colour to purple. To prepare this carbonate, it 

 is necessary to pass carbonic acid gas through boiling alcohol containing a 

 quantity of mauveine in suspension. It is then filtered quickly, and car- 

 bonic acid passed through the filtrate an til nearly cold. On standing, 

 this liquid will deposit the carbonate as prisms, having a green metallic 

 reflexion. A solution of this salt, on being boiled, loses part of its carbonic 

 acid and assumes the violet colour of the base. When dry this carbonate 

 rapidly changes, and if heated to 100° C. loses nearly all its carbonic acid 

 and changes in colour to a dull olive ; therefore, as it cannot be dried with- 

 out undergoing a certain amount of change, its composition is difficult to 

 determine. However, I endeavoured to estimate the carbonic acid in this 

 salt by taking a quantity of it freshly prepared and in the moist state, and 

 heating it in an oil-bath until carbonic acid ceased to be evolved. The 

 residual base was then weighed, and also the carbonic acid, which had 

 been collected in a potash bulb, having been previously freed from water 

 by means of sulphuric acid. The following results were obtained : — 



I. 1 "88 residual base obtained ; '190 carbonic acid evolved. 



II. 1*375 residual base; '1385 carbonic acid evolved. '190 of CO^ is 

 equal to *268 of H2CO3; this, added to the residual base, will give the 

 amount of substance experimented with, viz. 2*148. The amount of COg 

 obtained from this quantity, therefore, is 8*8 per cent. 



Calculating the second experiment in a similar manner, the amount of 

 carbonate operated upon would be 1*5702 grm. ; the percentage of COj 

 obtained is therefore equal to 8 '8. A carbonate having the formula 

 (Cj^ NJ2 H2 COg would contain 5*1 per cent, of CO2, and an acid 

 carbormte having the formula Og^Hg^N^, CO3 would contain 9*4 per 

 cent, of CO2. 



Considering that this salt when prepared begins to crystallize before it 

 is cold, probably the first portions that deposit are a monocarbonate, while 

 the larger quantity which separates afterwards is an acid carbonate. Hence 

 the deficiency in the amount of CO2 obtained in the above experiments. 

 I hope to give my attention to this remarkable salt at a future period. 



In the analysis of the salts of mauveine great care has to be taken in 

 drying them thoroughly, as most of them are highly hygroscopic. 



I am now engaged in the study of the replaceable hydrogen in mauveine, 

 which I hope will throw some light upon its constitution. From its for- 

 mula I believe it to be a tetramine, although up to the present time I 

 have not obtained any definite salts with more than 1 equiv. of acid. 



When mauveine is heated with aniline it produces a blue colouring 

 matter, which will doubtless prove to be a phenyle derivative of that base. 

 A salt of mauveine when heated alone also produces a violet or blue 

 compound. These substances I am now examining, and hope in a short 

 time to have the honour of communicating them to the Society. 



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