292 ANNUAL OF SCIENTIFIC DISCOVERY. 



sulphuret of ammonium, protosulphate of iron, which destroy the rose 

 tint very rapidly ; the protochloride of tin produces a blue tint before it 

 decolorizes it. The reduction of the murexide gives birth to a new sub- 

 stahce, which, in its turn, may reproduce that substance by a properly 

 conducted oxidization. 



From these reactions it is evident that the rose, amaranthus, and pur- 

 ple shades produced with the murexide, and which exceed those produced 

 by all other means in richness and brilliancy of tints, have also the ad- 

 vantage of being the most solid and durable, an advantage which will no 

 doubt be soon appreciated. 



We have now to speak of the sources from whence the supply of uric 

 acid may be obtained, should the employment of murexide become gen- 

 eral. At present the price of that substance, which has never hitherto 

 become an article of commerce, would be so high that the murexide- pur- 

 ple would be far more expensive than that produced with cochineal ; but 

 if we recollect that, independent of the excrements of serpents, from 

 which hitherto uric acid has been made, those of pigeons, and especially 

 of all carnivorous birds, silkworms, &c., and above all Peruvian guano, 

 which may be obtained in immense quantities, are very rich in uric acid, 

 and it may be produced from them at a very moderate price as soon as it 

 becomes an article of commerce. No doubt, if necessary, fowls might be 

 so fed as to produce it in much larger quantities than they do naturally. 



Connected with this part of the subject, we may mention that, in the 

 making of the alloxan from the uric acid, a considerable quantity of the 

 former remains in the acid mother-liquid, from which the crystals of al- 

 loxan separate. This portion could not be used to impregnate tissues, in 

 consequence of the nitric acid present, and would cause a considerable 

 loss of material, and a considerable enhancement of the cost of the dye, 

 unless it could be utilized. If a piece of zinc be introduced into the acid 

 mother-liquid, alloxantine will be formed, which may be recovered by 

 evaporating the liquid and allowing it to separate out. This substance, 

 as we have before remarked, will also produce the purple color, and a 

 mixture of it with alloxan will afford the best conditions for its production. 

 M. Schlumberger has indulged some curious speculations relative to the 

 existence of this coloring matter ready formed in nature, which it may be 

 interesting to notice. M. Sacc has found that poultry, and especially 

 birds with very brilliant plumage, such as the different paroquets, do not 

 produce sensible traces of uric acid during their period of moulting, whilst 

 the quantity is very large when their feathers are fully developed. The 

 question naturally suggests itself, What becomes of the uric acid in the 

 former case ? May it not be transformed by some as yet unknown meta- 

 morphosis in the animal body into a substance like alloxan, capable of col- 

 oring the feathers ? Murexide, as we have observed, is green by reflected 

 light ; a substance, then, which gives violet (red and blue) and green (yel- 

 low and blue) can undoubtedly produce all shades of colors, which are 

 made up of those three colors. How curious if it should hereafter be 



