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THE POPULAR SCIENCE MONTHLY. 



crystalline specks that the whole has the rounded appearance as in Fig. 

 3. The arborescent crystals that succeed the fringes, from a saturated 

 solution, are smaller in their foliage than the last, and end in small 

 spherical or botryoidal knobs. 



Besides these various forms, there occur all kinds of crystalline com- 

 binations, as for instance the spray sketched in Fig. 4, when the long 



and rough branches have terminated 

 each in a large hexagonal plate and the 

 flowing past of a weak solution has 

 afterward caused the growth of delicate 

 fern-leaves. Often, also, a large expan- 

 sion will take place in every direction, 

 though joined to the parent stem by 

 an almost invisible thread ; or, from 

 the point of a long crystal there will 

 branch out to right and left crescent- 

 shaped structures, a process the commencement of which is seen in one 

 of the side rays of Fig. 1. The last traces of silver will frequently give 

 rise to delicate crystalline filaments wandering over the surface of the 

 glass, as in Fig. 5. 



If a piece of zinc be placed in a solution of neutral terchloride of 



Fig. 5. 



Fig. 6. 



gold, containing about nine per cent, of salt, there is an immediate out- 

 growth of black gold, which speedily changes to an advancing mass 

 of yellow or perhaps lilac metal of lichen-like forms, from which 

 proceed beautiful fringes of yellow or black, ending generally in such 



