Dr. Schunck on Rubian and its Products of Decomposition. 435 



I am unwilling to draw any inference from tlie greater or less 

 correspondence of either of these calculations with the experi- 

 mental result^ because I am not convinced of the absolute purity 

 of the specimen employed for analysis. 



The lead compound of rubiagine was prepared by adding a 

 small quantity of an alcoholic solution of sugar of lead to a con- 

 centrated alcoholic solution of the substance, taking care not to 

 employ an excess of the precipitant. The orange-coloured pre- 

 cipitate was collected on a filter, washed with alcohol, dried and 

 submitted to analysis. 



0*4610 grm., dried in the water-bath, gave 0*5290 carbonic 

 acid and 0*1110 water. 



0*2010 grm. gave 0*1460 sulphate of lead, containing 0*10742 

 oxide of lead. 



In 100 parts it contained therefore — 



Carbon 31*29 



Hydrogen 2*67 



Oxygen 12*60 



Oxide of lead .... 53*44 



These numbers do not decide between the two formulae, since 

 they correspond equally well with C^^ H'^ O'^ + SPbO and 

 Q44 JJ17 0'3-j-4PbO, as the following calculation shows :— 



Carbon . 

 Hydrogen . 

 Oxygen . . 

 Oxide of lead 



If C^^H^'^O'^ be the true formula of rubiagine, then it is 

 formed by rubian taking up 4 equivs. of water and splitting up 

 into 1 equiv. of rubiagine and 2 equivs. of sugar, as seen by the 

 following equation : — 



2 eqs. of Sugar = Cm'^'^O^'^X _ f C^H^^O^o = 1 eq. of Rubian. 

 1 eq.of Rubiagine= C32JJ14010 J -\ H ^0 4=4eqs.ofWater. 



C56JJ38034 C^H^^O^ 



If, on the other hand, C^H^^'O^^ be the correct formula, then 

 1 equiv. of rubian loses 5 equivs. of water, and splits up into 1 

 equiv. of rubiagine and 1 equiv. of sugar, for 



C44Hi70^3 + Ci^H^2oi2 + 5HO = C^H^03o. 



Rubiadipine. — This substance is a characteristic product of the 

 fermentation of rubian. I have never subjected rubian to the 

 action of ferment, under ordinary circumstances, without being 

 able to detect it among the bodies formed. In its appearance 

 and general properties it resembles rubiretine. It dififers from 



