ALKALOIDS. 611 



then to rose-pink, and finally to yellow. This reaction may still be 

 noticed with -g^-g^ grain of strychnine (Plate VI., 5). 



3. Sonnemchein's ted. When to a very small quantity of strych- 

 nine, dissolved in a drop of sulphuric acid, some ceroso-ceric oxide is 

 added, and the mixture is stirred with a glass rod, a deep-blue color 

 is produced, changing soon to violet, and finally remaining cherry- 

 red. One part of strychnine in one million parts of water can thus 

 be recognized. The reagent may be made by heating cerium oxalate 

 to redness and dissolving it in 30 times its weight of sulphuric 

 acid. 



4. Solutions of strychnine give with diluted solution of potassium 

 dichromate a yellow, crystalline precipitate, which, when collected, 

 washed, and heated with concentrated sulphuric acid, shows the play 

 of colors described in test 2. A play of colors similar to the above 

 is shown under identical conditions by mixtures of other alkaloids ; 

 for instance, by morphine containing 10 per cent of hydrastine. 



5. Neutral solutions of strychnine give yellow precipitates with 

 the chlorides of gold and platinum and with picric acid; a white 

 precipitate with mercuric chloride, potassium hydroxide, and with 

 chlorine-water ; a greenish-yellow precipitate with potassium ferro- 

 cyanide. 



Brucine, C 23 H 26 N 2 O 4 .4H 2 O. This alkaloid is found associated 

 with strychnine in various species of Strychnos. It is readily soluble 

 in alcohol, amyl alcohol, and chloroform, but sparingly soluble in 

 cold water and in ether. 



Analytical reactions : 



1. To 1 c.c. of water add 5 drops of nitric acid and 5 milligrammes 

 of brucine ; a deep blood-red color results. Heat the liquid until it 

 has assumed a yellow color, then add 9 c.c. of cold water and a few 

 milligrammes of sodium thiosulphate (or a small crystal of stannous 

 chloride) ; a beautiful amethyst or violet color results (Plate VI., 6). 



2. Fresh chlorine water, added drop by drop to a concentrated 

 brucine solution, produces a red color, turning violet, and becoming 

 colorless on addition of an excess of chlorine. 



Veratrine, Veratrina. This is a mixture of alkaloids obtained 

 from the seed of Asagraa officinalis. It is a white, amorphous, rarely 

 crystalline powder, highly irritating to the nostrils ; nearly insoluble 

 in water, readily soluble in alcohol. 



Analytical reactions : 



1. Concentrated sulphuric acid causes with veratrine first a yellow, 



