464 Miscelldneous Intelligence. 



are known to be unchanged by water : during a long experiment 

 they change colour, becoming, first, violet, tiien blue. 



Experiments similar to that with the copper, when repeated with 

 the same solutions, &c., but the substitution of plates of lead and tin 

 for the copper plates, produced crystalline double chlorides of these 

 metals and sodium. 



Muriate of ammonia being substituted for common salt in these 

 experiments, another series of double compounds was obtained with 

 copper, silver, lead, and zinc. 



A double chloride of barium and lead was formed slowly in a 

 similar way. 



When a solution of the iodide of potassium or sodium was used 

 instead of the solution of salt, then double iodides were obtained : 

 thus with lead rather a rapid formation of silky crystals occurred 

 upon the lead, which, when examined by water, were decomposed, 

 producing iodide of lead and solution of iodide of potash or soda. 

 A tube two or three times the diameter of the former may be used 

 for the experiment. 



The second method of producing new combinations by weak 

 electro-chemical powers, depends upon the electro-motive action, 

 which is caused whenever a metal touches the oxides, or an oxide 

 of another metal. If an oxide of a metal, a plate of metal, and a 

 liquid be put into a tube closed at one extremity, there will be an 

 electro-motive action of the metal with the oxide, and of the liquid 

 with both these bodies ; and the chemical effect will be according to 

 the resultant of these three forces, which can only be ascertained 

 by experiments. 



As an illustration of the effects thus produced, three tubes, from 

 eight to twelve hundredths of an inch in diameter, were prepared, a 

 little protoxide of lead being put into one, deutoxide into the se- 

 cond, and peroxide into the third ; solution of muriate of ammonia 

 and a plate of lead were then added to each tube. After a time, 

 lead was precipitated in the first tube, very slight chemical changes 

 took place in the second, but a large quantity of double chloride of 

 lead and ammonia crystallized upon the lead in the third, in the 

 form of needles. Thus very different effects were produced, accord* 

 ing to the state of oxidation. 



Solution of salt gave similar results with the oxides of lead and 

 lead. 



The oxides of copper, with solutions of alkaline muriates, gave 

 curious results. With muriate of ammonia, crystals were produced 

 of considerable size, and different to those obtained by the former 

 process. In this experiment, the black and anhydrous deutoxide of 

 copper gradually acquired a blue colour, as if a hydrate were 

 formed under the influence of the feeble electric current formed 

 by the arrangement. 



, Copper, its deutoxide, and solution of corrosive sublimate, pro- 

 duced a double chloride, crystallizing in plates, and possessing a 

 metallic lustre. 



