ALKALOIDS. 601 



narcotine), amyl alcohol (except veratrine and quinine), benzene, and 

 benzin. 



7. The solid alkaloids, as well as their salts, may be obtained in a 

 crystalline state. 



8. Most alkaloids are white, have a very strong, generally bitter, 

 taste, and act very energetically upon the animal system. 



9. From the aqueous solutions of alkaloid salts, the solid alkaloids 

 are precipitated by alkali hydroxides, in an excess of which reagents 

 some alkaloids (morphine, for instance) are soluble. Alkali car- 

 bonates and bicarbonates liberate all, and precipitate most alkaloids ; 

 not precipitated by bicarbonates are strychnine, brucine, veratrine, 

 atropine, and a few rare alkaloids. 



Most alkaloids give precipitates with tannic acid, picric acid, 

 phospho-molybdic acid, potassium mercuric iodide; and the higher 

 chlorides of platinum, gold, and mercury. These precipitates are 

 similar in properties and composition to those formed with ammonia. 



Most alkaloids give beautiful color reactions when treated with 

 oxidizing agents, such as nitric acid, chloric acid, chromic acid, ferric 

 chloride, chlorine water, etc. 



A decinormal solution of mercuric-potassium iodide, HgI 2 .(KI) 2 , made by 

 dissolving 13.546 grammes mercuric chloride and 49.8 grammes potassium 

 iodide in 1000 c.c of water, is known as Mayer's solution. This precipitates all 

 alkaloids, forming with them white or yellowish-white, generally crystalline 

 compounds. The solution has been used for volumetric determination of alka- 

 loids, but the method is now discarded, as the results are not accurate. (In 

 most cases the alkaloid replaces the potassium in the potassium-mercuric iodide.) 



Phospho-molybdic acid, mentioned above as a reagent for alkaloids, is pre- 

 pared as follows : 15 grammes ammonium molybdate are dissolved in a little 

 ammonia water and diluted with water to 100 c.c. This solution is poured 

 gradually into 100 c.c. of nitric acid, specific gravity 1.185, and to this mixture 

 Is added a warm 6 per cent, solution of sodium phosphate as long as a precipi- 

 tate is produced. This precipitate is collected on a filter, washed and dissolved 

 in very little sodium hydroxide solution ; the solution is evaporated to dryness, 

 further heated until all ammonia has been expelled and the residue dissolved 

 in 10 parts of water. To this solution is added a quantity of nitric acid suffi- 

 cient to redissolve the precipitate which is formed at first. This reagent gives 

 precipitates not only with the alkaloids, but also with the salts of potassium 

 and ammonium. 



General mode of obtaining 1 alkaloids. The disintegrated veg- 

 etable substance (bark, seeds, etc.) is extracted with acidified water, 

 which dissolves the alkaloids. When the alkaloid is volatile, it is 

 obtained from this solution by distillation, after having been liberated 

 by an alkali. 



