400 CONSIDERATION OF CARBON COMPOUNDS 



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. 



5. Neutral solutions of strychnine give yellow precipitates with the 

 chlorides of gold and platinum and with picric acid ; a white precipi- 

 tate with mercuric chloride, potassium hydroxide, and with chlorine 

 water ; a greenish-yellow precipitate with potassium ferrocyanide. 



If to the last-named precipitate, after careful decantation of the 

 liquid, sulphuric acid is added, a similar play of colors is produced 

 as stated in reactions 2 and 3. 



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 VII., 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. 



Atr opine, Atropina, C I7 H 23 NO 3 = 289 (Daturine). Occurs in 

 Atropa belladonna. It is a white, crystalline powder, having a bitter 

 and acrid taste and an alkaline reaction ; it is sparingly soluble in 

 water, but very soluble in alcohol and chloroform. Atr opine sulphate, 

 (C 17 H 23 NO 3 ) 2 .H 2 SO 4 , is a white, crystalline powder, easily soluble in 

 water. 



Analytical reactions: 



1. Atropine dissolves in concentrated sulphuric acid without color. 



2. The above solution is not colored by nitric acid (difference from 

 morphine), and not at once by potassium dichromate (difference from 



