540 



Action of Potash on Datiscine and Datiscetine. It was stated in a 

 previous part of this paper that datiscine and datiscetine dissolve in 

 cold solutions of the alkalies without decomposition, and that datis- 

 cine, when boiled with potash, is decomposed with the formation of 

 datiscetine. It only remained, therefore, to try the action of fused 

 hydrate of potash. Datiscetine, when added in small successive 

 portions to fused hydrate of potash, assumed a deep orange colour, 

 and then dissolved with the evolution of hydrogen gas. When the 

 disengagement of hydrogen had ceased, the mass was dissolved in 

 water and supersaturated with hydrochloric acid. A partly resinous 

 substance separated, which, by sublimation, yielded perfectly colour- 

 less, long crystals closely resembling benzoic acid. Their solution 

 in water on the addition of perchloride of iron gave that deep violet 

 tint which disappears on the addition of hydrochloric acid, and is so 

 characteristic of salicylic acid. 



Action of Chromic Acid on Datiscetine. On distilling datiscetine 

 with bichromate of potash and sulphuric acid a liquid came over, 

 containing no oily drops, but having the smell of salicylous acid, 

 and which, when tested with a persalt of iron, formed a purple- 

 coloured solution characteristic of that acid. 



It follows therefore, I think, from the experiments already de- 

 tailed, that datiscine, like salicine, phloridzine, &c., is a glucoside, 

 and that it approaches nearer to salicine than any other glucoside, 

 with the exception of populine, yet known. 



I will conclude this account of datiscine by proposing the follow- 

 ing practical application. As is well known, the colouring matter 

 of madder, when boiled with dilute sulphuric acid, is changed into 

 sugar and garancine, a new dye-stuff, which, for many purposes, is 

 found superior to that originally present in the madder. Within 

 the last twelve months Mr. Lieshing, by treating the colouring 

 matters in weld and quercitron bark with dilute sulphuric acid, has 

 resolved them into new colouring matters, which are but slightly 

 soluble in water, and are found nearly three times more powerful as 

 dye-stuffs than the original colouring matters from which they had 

 been produced. 



As datiscine, when boiled with dilute sulphuric acid, undergoes 

 a perfectly similar transformation, being resolved into sugar and 

 datiscetine, which has a much higher colouring power than the 



