148 



Dr. Stenhouse on Rubia munjista. 



[1864. 



quantity of an oil, having an aromatic odour, resembling that produced from 

 ciunamic acid by the action of hypochlorite of lime. 



Tinctorial power of Munjistine and Munjeet. 



Prof. Runge stated, in 1835, that munjeet contains twice as much avail- 

 able colouring matter as the best Avignon madder. This result was so unex- 

 pected, that the Prussian Society for the Encouragement of Manufactures, 

 to whom Professor Runge' s memoir was originally addressed, referred the 

 matter to three eminent German dyers, Messrs. Dannenberger, Bohm, and 

 Nobiling. These gentlemen reported, as the result of numerous and carefully 

 conducted experiments, that so far from munjeet being richer in colouring- 

 matter than ordinary madder, it contained considerably less. This conclu- 

 sion has been confirmed by the experience of my friend Mr. John Thom, 

 of Birkacre, near Chorley, one of the most skilful of the Lancashire printers. 



From a numerous series of experiments I have just completed, I find 

 that the garancine from munjeet has about half the tinctorial power of the 

 garancine made from the best madder, viz. Naples Roots. These, however, 

 yield only about 30 to 33 per cent, of garancine, while munjeet, according 

 to my friend Mr. Higgin, of Manchester, yields from 52 to 55 per cent. 

 Taking the present prices therefore of madder at 36 shillings per cwt., and 

 munjeet at 30 shillings, it will be found that there will be scarcely any 

 pecuniary advantage in using munjeet for ordinary madder-dyeing. The 

 colours from munjeet are certainly brighter, but not so durable as those 

 from madder, owing to the substitution of purpurine for alizarine. There 

 is, however, great reason to believe that some of the Turkey-red dyers are 

 employing garancine from munjeet to a considerable extent. When this is 

 the case they'evidently sacrifice fastness to brilliancy of colour. By treating 

 such a garancine with boiling water, and precipitating by an acid in the 

 way already described, its sophistication with munjeet may very readily be 

 detected. The actual amount of colouring matter in munjeet and the best 

 madder is very nearly the same ; but the inferiority of munjeet as a dye- 

 stuff results from its containing only the comparatively feeble colouring 

 matters, purpurine and munjistine, only a small portion of the latter being 

 useful, whilst the presence of munjistine in large quantity appears to be 

 positively injurious. So much is this the case, that when the greater part 

 of the munjistine is removed from munjeet-garancine by boiling water, it 

 yields much richer shades with alumina mordants than before. 



PURPUREINE. 



Action of Ammonia on Purpurine. 

 "When purpurine is dissolved in dilute ammonia and exposed to the air in 

 a vessel with a wide mouth in a warm place for about a month, ammonia 

 and water being added, from time to time as they evaporate, the purpurine 

 almost entirely disappears, whilst a new colouring-matter is formed which 

 dyes unmordanted silk and wool of a fine rose-colour, but is incapable of 



