Page:Popular Science Monthly Volume 14.djvu/451

Rh assume the appearance of fern-leaves; while the growth from a still stronger liquid reminds us rather of a furze-bush. If the nitrate of silver amount to fifteen per cent, or thereabouts, there occurs a steady advance of brilliantly white moss; and, if the solution be saturated, or nearly so—say forty per cent.—this moss is very sturdy, often ending in solid crystalline knobs, or stretching out into the liquid as an arborescent fringe.

In all these cases, however, when the solution in front of the growing crystals has been somewhat exhausted, certain prominent or well-circumstanced crystals seem to monopolize the power, and to push forward through the remaining portions of the liquid. This raises beautiful branches which assume a variety of graceful forms, which it is hopeless to attempt to portray by diagrams, but the subjoined figures give some of the more characteristic outlines greatly magnified. The weak solutions produce feathery crystals, as somewhat in Fig. 1, consisting of



a straight central stem from which grow on either side crystalline rays that terminate in a sharp point, and frequently become themselves the center stem of a similar crystalline structure.

In the outlying growth of a moderately strong solution the apparent regularity of the crystalline form is lost; the main stem is built of a confused mass of hexagonal plates, while the side branches are an agglomeration of minute pointed crystals turning in every direction, and producing such jagged outlines as in Fig 2.



In still stronger solutions the branches lose every appearance of straightness, and they are built of hexagonal plates so studded with