A sun ray is a magical thing: we connect it in our fancy with the most ethereal of possible creations. Yet in its action on matter it produces colour; it separates the particles of solid masses farther from each other, and it breaks up some of the strongest forces of chemical affinity. To modern science is entirely due the knowledge we have gained of the marvellous powers of the sunbeam; and it has rendered us familiar with phenomena, to which the incantation scenes of the Cornelius Agrippas of the dark ages were but ill-contrived delusions, and their magic mirrors poor instruments. The silver tablets of the photographic artist receiving fixed impressions of the objects represented in the dark chamber by a lens, are far superior as examples of natural magic.
In the dark ages, or rather as the earliest gleams of the bright morning of inductive research were dispelling the mists of that phantom-peopled period, it was observed, for the first time, that the sun’s rays turned a white compound black. Man must have witnessed, long before, that change which is constantly taking place in all vegetable colours: some darkening by exposure to sunlight, while others were bleached by its influence. Yet those phenomena excited no attention, and the world knew nothing of the mighty changes which were constantly taking place around them. The alchemists--sublime pictures of credulous humanity--toiling in the smoke of their secret laboratories, waiting and watching for every change which could be produced by fire, or by their “royal waters,” caught the first faint ray of an opening truth; and their wild fancy, that light could change silver into gold, if they but succeeded in getting its subtile beams to interpenetrate the metal, was the clue afforded to the empirical philosopher to guide him through a more than Cretan labyrinth.[117]
The first fact recorded upon this, point was, that horn silver blackened when exposed to the light. Without doubt many anxious thoughts were given by these alchemists to that fact. Here was, as it appeared, a mixing up of light and matter, and behold the striking change! It was a step towards the realization of their dreams. Alas! poor visionaries! in pursuing an ideality they lost the reality which was within their grasp.
