OEGANIC POISONS AND DEUGS 113 



without colour in concentrated sulphuric acid, and the 

 introduction into the solution of a fragment of potassium 

 bichromate yields a characteristic violet colour, passing 

 quickly into rose pink, which is persistent for some time. 

 The colour is produced in streaks on moving the bichromate 

 crystal through the liquid. (3) When bichromate solution is 

 added to a solution of strychnine in dilute acetic acid, 

 the sparingly soluble strychnine chromate separates in 

 crystals. The precipitate gives with concentrated sul- 

 phuric acid the same colour reaction as described under (2). 

 Although strychnine is amongst the most stable and 

 easily recognised alkaloids, error is possible. When organic 

 impurities are considerable, reduction of chromate and 

 sulphuric acid may occur with simulation of the strychnine 

 colours, and, moreover, those colours proper to strychnine 

 may be effectually marked. Further, many residues, 

 especially those derived from herbivorous stomach contents, 

 give a precipitate with chromate in dilute acetic acid, .which 

 is, however, amorphous, although with concentrated sul- 

 phuric acid it gives a red colour. In such doubtful cases 

 the physiological action of the extract ought to be tested 

 on a mouse, for which x/inr grain of strychnine is lethal 

 within ten minutes. 



EEFEEENCES TO STRYCHNINE. 



1 T. Hodgkins, Vet. Jl., 1907, p. 411. 



2 Anon, Vet. Becord, 1906, p. 356. 



3 G. MoCall, Vet. Jl., 1907, p. 277. 

 * Bock, Vet. Jl., 1907, p> 447. 



6 N. Howe, Vet. Becord, 1898, p. 325. 

 8 J. Macer, Vetermariam, 1870, p. 209. 

 ^ Gowring, Veterinarian, 1870, p. 209. 

 8 YoTiatt, Veterinarian, 1840, p. 28. 



MORPHINE AND OPIUM. 



Forms and Occurrence. — Opium is the inspissated juice 

 of the opium poppy, Papaver somnifervm, which is native to 

 Southern Europe and the Levant, though cultivated and 



