Mr. Grove on some Electro-Nitrogurets. 101 



the residue in the tube had changed colour from chocolate to 

 red, and had all the characters of pure copper. 



I now tried nickel and silver with the nitrate of ammonia 

 and gold with the muriate ; with nickel very little spongy matter 

 was formed ; I could not collect sufficient for analysis, and 

 the fearful nature of the ammoniacal precipitate prevented 

 my collecting sufficient of the silver deposit. To obtain an 

 analogous compound of gold I mixed its chloride with a so- 

 lution of muriate of ammonia, and electrolysed with platina 

 electrodes, divided by a pipe-clay diaphragm, to prevent the 

 reaction of the chlorine ; a black deposit was formed, which 

 did not float, and was but little coherent ; its specific gravity 

 was 10*3, and five grains gave 0*05 cubic inch of gas ; from 

 the small quantity obtained I could not positively pronounce 

 as to its nature, but it appeared to be nitrogen. 1 have also 

 formed amalgams by using mercury at the cathode with zinc, 

 &c. at the anode, but the mercury, even when alloyed, would 

 not retain the gases, and the amalgam yielded no more than 

 the solid metal alone would have done. 



In forming each of these substances the process must be 

 continually watched, as, if the solution of the metal be in ex- 

 cess with respect to that of the ammoniacal salt, the metal is 

 reduced alone; this is easily noted in the case of copper from 

 the difference of colour ; at a certain stage of the process the 

 chocolate coagulum becomes fringed with dendritic fibres of 

 pure copper, and the line of demarkation is clearly visible; in 

 the zinc and cadmium compounds this effect is not so evident, 

 but a very little practice enables one to recognize the differ- 

 ence, the pure metal being of a lighter gray, and assuming a 

 regular arborescent appearance instead of the amorphous 

 sponge ; it generally commences on the under part, from the 

 greater specific gravity of the metallic solution ; when this re- 

 duction of pure metal has once commenced it continues, and 

 to form again the nitroguret, the solution must be changed, 

 and the process commenced de novo. 



In all these compounds the quantity of nitrogen is far un- 

 der the equivalent proportion, and in many cases gradations 

 of shade could be observed in the sponge, on which occasions 

 less nitrogen was found to have entered into combination ; 

 these gradations were somewhat abrupt, the mass having a 

 stratified appearance like clay of different shades rolled up; 

 the averages I have given were from portions of the deepest 

 colour ; an increase of power did not deepen it beyond a cer- 

 tain point ; but whether a very high power will cause more 

 nitrogen to combine with the metals, I have as yet had no 

 opportunity of proving. 



