128 0:S THE FOEMATIO>' OF MOSS GOLD A.VD SILTEE. 



Moss SiLA'EE. 



^ext a series of experiments was made in order to ascertain 

 whether any light would be thrown upon the subject by the 

 behaviour of silver compounds under somewhat similar conditions. 



The first experiment was the reduction of silver chloride, in a 

 bulb tube, by the passage of a current of pure dry hydrogen, 

 mentioned byDr.Percy,P.E.S., in his great work on '' Iletallurgi/^''' 

 and by other writers. 



The silver chloride was allowed to fuse, but the temperature was 

 kept very much below the fusing point of silver, so much so that 

 the glass was not even softened. 



The surface of the reduced metal was somewhat mammilated 

 and cavernous, and it was found in certain places to be covered 

 with minute capillary threads and spiculse of silver ; the cavities 

 also were more or less filled with them. 



Some silver sulphide was prepared in the humid way from 

 silver nitrate. This was well washed, dried, and transferred to 

 a Trench crucible, and then fused under a layer of borax in an 

 ordinary melting furnace. 



The mass of sulphide, weighing about 2 ozs., was then cut in 

 two by means of a large knife and hammer, and one of the two 

 parts roasted in a muffle furnace. The piece of silver sulphide 

 was placed on a small scorifier just inside the mouth of the 

 muffle, where for some time the temperature did not exceed the 

 melting point of tin {i.e. about 442° E.) "Within a very few 

 minutes (between 10 and 15 minutes) after the lump of silver sul- 

 phide had been placed in the muffle, beautiful little growths of 

 metallic silver were seen to be dotted over its surface, and 

 particularly near the upper edges ; the lower portion of the mass, 

 to a height of about i inch only presenting one or two points 

 of silver at the right-hand end. This experiment was repeated 

 several times with fresh pieces of the silver sulphide. 



The projecting filaments had a most brilliant silver-white 

 colour and lustre. 



Their surfaces are strongly striated parallel to the length of 

 the filament, and the larger ones are in most cases more or less 

 curved or spirally convoluted. Towards the base the majority- 

 become much thicker, and in one direction they are usually much 

 broader than in the other, hence they in this respect somewhat 

 resemble blades of grass. 



In certain instances the crystals could almost be seen to 

 lengthen — a perceptible increase in length in more than one 

 instance was observed within the space of between one and two 

 minutes. 



The crystals seem to increase in length and thickness far more 

 rapidly during the first hour than afterwards, and their growth 

 does not appear to be materially hastened by urging the tem- 



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