Chemical Science, 399 



was ultimately led to the following explanatory experiment: — 

 prepare an arsenical liquid, pour it into three glasses, and add to 

 one portion an excess of caustic-potash ; to the second, excess of 

 caustic-soda ; and to the third, excess of caustic-ammonia. On 

 adding lime-water, a deposit of arsenite of lime will be formed 

 equally in each of the glasses. Now add to each a few drops of 

 acid, (for instance, nitric acid,) yet so that in all the alkali shall 

 predominate ; whilst no solution of the precipitate will take place 

 in the glasses that have the potash and soda in them, it will im- 

 mediately begin in that with the ammonia ; and all the arsenite 

 of lime will be finally dissolved, although the ammonia be not 

 saturated by the acid which has been added. Of course, the solu- 

 tion will take place in the three glasses when any acid is in excess ; 

 yet, on saturating the acid with alkali, the precipitate will be 

 re-formed immediately in those glasses that contain the potash or 

 soda, but not in that which holds the ammonia, however one may 

 neutralize the liquid. 



By putting muriate or nitrate of ammonia into a liquid con- 

 taining arsenic, and adding lime-water in any quantity, no pre- 

 cipitate will be formed, even though heat be applied. Thus it 

 will be seen, that it is not the ammonia, as caustic alkali, which 

 retains the arsenite of lime in solution, but it is the presence of a 

 soluble salt of ammonia which prevents the formation of the de- 

 posit ; and if, instead of ammonia, caustic potash or soda be used 

 in the process described by Berzelius, then lime-water will in- 

 stantly form the precipitate of arsenite of lime. — Phil. Mag. lxvi. 

 253. 



13. Artificial Gold, a new alloy. — Hanover. M. Dittmer has 

 described in the Hanoverian Magazine the following compound of 

 different metals, prepared by the privy- counsel lor Dr. Hermstadt, 

 and which may supply the place of gold, not only as to colour, but 

 also for its specific gravity and ductility. The materials con- 

 sist of 16 parts, by weight, of virgin platina, 7 parts of copper, 

 and 1 part of zinc, equally pure ; these metals are to be mixed 

 together in a crucible, covered with powdered charcoal, and per- 

 fectly fused so as to form a homogeneous mass. — Rev. Ency. xxvii. 

 900. 



14. Simple mode of obtaining Meconiate of Morphia. — The follow- 

 ing process is by Dr. Giuseppe Meneci : reduce good opium to 

 powder, put it into a paper filter, add distilled water to it, and 

 slightly agitate it ; in this way wash it till the water passes 

 through colourless ; then pass a little diluted alcohol through it ; 

 dry the insoluble portion (now diminished to one-halft, in a dark 

 place ; digest it, when dry, in strong alcohol for a few minutes, 

 applying heat ; separate the solution, which, by cooling and after- 



2 E 2 



