Moss — The Taxine in Irish Yew. 95 



vacuo over sulphuric acid, is placed between microscope cover-glasses, held 



together by a clip, it is possible, uuder a low magnifying power, to detect 



indications of softening, at a temperature of 60°, twenty-two degrees below 



the reputed melting-point. 



Thorpe and Stubbs obtained a chloride, a sulphate, and a compound with 



gold chloride, having each a composition closely corresponding to that 



indicated by theory. I find that taxine dissolved in ether may be titrated 



N 

 with ^ hydrochloric acid in the manner sometimes used for the titration of 



alkaloids, using a minute quantity of methyl orange as indicator.^ Taxine 

 weighing 0'2790 gramme took 0'0159 gramme hydrochloric acid, instead of 

 0'0151 indicated by theory on the assumption that the hydrochloride is 



C3,H„0;oN, HCl. 



Thorpe and Stubbs point out that the alkaloid is decomposed when 

 warmed in the water-bath with dilute hydrocliloric acid, one of the products 

 being a brown substance. I find that, even without warming, some decompo- 

 sition takes place. When 0"6026 gramme of taxine was dissolved in 0'3 c.c. of 

 hydrochloric acid diluted with 2 c.c. of water, and placed in a vacuum over 

 caustic potash, the residue was of a dark-brown colour. On prolonged drying 

 over sulphuric acid, it was found that the increase in the weiglit of the taxine 

 was 0-0400 gramme, instead of 0'0328 required theoretically for the formation 

 of the hydrochloride. On treating the solid obtained in this way with water, 

 most of it dissolved, leaving a brown humus-like substance. On adding 

 ammonia to the solution, a brown precipitate is thrown down ; and on 

 shaking with ether, and allowing the liquids to separate, they are both 

 coloured brown. When the ethereal solution was shaken with dilute hydro- 

 chloric acid, and ammonia added to the acid liquid, tlio precipitate was again 

 brown ; and on standing in the liquid for a few days, it aggregated to oily- 

 looking brownish spheres about a millimetre in diameter. It is clear that 

 under the conditions described hydrochloric acid has a marked action upon 

 taxine at ordinary temperatures. It is doubtful whether the use of a 

 mineral acid, even highly dilute, is admissible in the extraction of the alka- 

 loid. In an experiment on the extraction of the alkaloid, by means of a 

 1 per cent, solution of oxalic acid, instead of dilute sulphuric acid, acting on 

 the leaves ; and using dilute oxalic acid, instead of dilute hydrochloric acid, 

 to remove taxine from its ethereal solution, I obtained a final precipitate 

 corresponding to 0'402 per cent, of taxine, against 0'323 per cent, when 

 mineral acids were employed. 



' " Commercial Organic Analysis," A. H. AUen, vol. iii., part ii., page 131, foot-note. 



