CHEMICAL SCIENCE. 239 



which he has discovered, provided that the alkaloid in question is one 

 of that class of bodies, the properties of which have been suitably 

 studied. Thus he will be able to discover coniine, nicotine, aniline, 

 picoline, petinine, morphine, codeine, narcotine, strychnine, brucine, 

 veratrine, colchicine, delphine, emetine, solanine, aconitine, atrophine, 

 and hyoscyamine. I do not pretend to say, that the chemical study 

 of all these alkaloids has been sufficiently well made to enable the 

 experimenter who detects one of them to know it immediately, 

 and affirm that it is such an alkaloid, and no other. Nevertheless, in 

 those even which he cannot positively determine or specify, he may 

 be able to say that it belongs to such a family of vegetables, the Sola- 

 naceae, for example. In case of poisoning by such agents, even this 

 will be of much importance. The method which I now propose for 

 detecting the alkaloids in suspected matters, is nearly the same as that 

 employed for extracting those bodies from the vegetables which con- 

 tain them. The only difference consists in the manner of setting 

 them free, and of presenting them to the action of solvents. We 

 know that the alkaloids form acid salts, which are equally soluble in 

 water and alcohol ; we know, also, that a solution of these acid salts 

 can be decomposed, so that the base set at liberty remains either 

 momentarily or permanently in solution in the liquid. I have observed 

 that all the solid and fixed alkaloids above enumerated, when maintained 

 in a free state and in solution in a liquid, can be taken up by ether when 

 this solvent is in sufficient quantity. Thus, to extract an alkaloid from 

 a suspected substance, the only problem to resolve consists in sepa- 

 rating, by the aid of simple means, the foreign matters, and then find- 

 ing a base which, in rendering- the alkaloid free, retains it in solution, 

 in order that the ether may extract it from the liquid. Successive 

 treatment by water, and alcohol of different degrees of concentration, 

 suffices for separating the foreign matters, and obtaining in a small 

 bulk, -a solution in which the alkaloid can be found. The bicarbo- 

 nates of potash or soda, or these alkalies in a caustic state, are 

 convenient bases for setting the alkaloids at liberty, at the same time 

 keeping them wholly in solution, especially if the alkaloids have been 

 combined with an excess of tartaric or of oxalic acid. 



To separate foreign substances, animal or otherwise, from the sus- 

 pected matters, recourse is commonly had to the tribasic acetate of 

 lead, and precipitating the lead afterwards by a current of sulphu- 

 retted hydrogen. As I have several times witnessed, this procedure 

 has many and very serious inconveniences. In the first place, the 

 tribasic acetate of lead, even when used in large excess, comes far 

 short of precipitating all the foreign matters ; secondly, the sulphu- 

 retted hydrogen, which is used to precipitate the lead, remains in 

 combination with certain organic matters, which undergo great 

 changes by the action of the air, and of even a moderate heat ; so 

 that animal liquids, which have been precipitated by the tribasic ace- 

 tate of lead, and from which the lead has been separated afterwards 

 by hydrosulphuric acid, color rapidly on exposure to the air, and 

 exhale at the same time a putrid odor, which adheres firmly to the 

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