Thomas J. Gregan

“ We must imagine what is taking place in the transparent solution. The silver, of course, existed at first in combination with the nitric element, and for every particle of silver deposited on the growing tree an equivalent particle of copper is dissolved from the surface of the plate. The nitric element never ceases to be in combination with a metal, but is transferred from the one metal to the other. ”

“ The gold will generally shoot its yellow branches rapidly round the margin of the drop. Such a running branch has been seen to stop on coming in contact with a loose piece of gold, which immediately in its turn becomes active, and commences to sprout on its farther side. Copper salts give round nodules, which have no crystal-line appearance when deposited from moderately weak solutions, but a very strong solution of the chloride—about forty per cent.—yields with zinc, first a thick, black growth, then arborescent fringes of red metal, terminating in crystals of very appreciable size. ”

“ If it be very weak—say one per cent.—the copper is fringed with black bushes of the metal, which in growing change color to white without any alteration of crystalline form that can be detected by a powerful microscope. A stronger solution gives white crystals from the commencement, which frequently 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 ”