ARTIFICIAL PRECIOUS STONES. 541 



solution as thick as molasses of silicate of soda, which brings about 

 a slow separation of the silicic acid. When, in so doing, he used a 

 solution of the sulphate of nickel protoxide, he obtained apple-green 

 stones, such as the chrysoprase. Thus we see that, as long as the 

 process of separation lasts, we may talk of the growth of precious 

 stones ; and we perceive, from the laws of crystallization, how by the 

 attraction of similar parts, and the exclusion of foreign ones, the forma- 

 tion of precious stones of perfectly " pure water " among the more im- 

 pure ones, which are frequently found, becomes more intelligible. 



Another process of crystallization is the slow cooling of molten sub- 

 stances. This can be explained very strikingly to students of chemistry 

 if a kettle of sulphur or molten bismuth is cooled slowly, until it is 

 covered with a crust of congealed matter, so to speak. Pierce that 

 crust in the middle, and pour out a portion of the liquid, and there will 

 form on the walls of the cavity thus created crystals of surpassing 

 beauty, and the whole assumes the appearance of a so-called crystal 

 druse, a form often assumed by amethysts and other half-precious 

 stones. It has been thought that, to make artificial diamonds, it was 

 necessary only to melt coal ; but, unfortunately, the results thus far 

 obtained are of no value. 



Nature's most successful way of producing precious stones was not 

 to dissolve minerals, but to put them into a fiery liquid condition, and 

 to separate the new productions slowly from their former impure parts 

 by chemical and electric influences, as we shall see directly. The earth, 

 like the sun and most fixed stars at present, was undoubtedly former- 

 ly in a fiery, liquid condition. Then the elements were commingled ; 

 all substances met, and entered the strangest combinations ; the whole 

 globe was an immense chemical laboratory. The earthy substances with 

 the light metals, at the last period of those gigantic processes, proba- 

 bly formed the " mother-liquor," from which, under various chemical 

 agencies, there separated now valuable metals, now grains of gold, and 

 still more frequently substances which were ennobled by crystallization. 

 The " mother-liquor," cooled with its productions, we call primitive for- 

 mations granite, feldspar, porphyry, etc. It may here be stated that 

 these primitive processes have recently been imitated in part, and that 

 two principal components of feldspar, albite and orthoclase, have lately 

 been obtained from a fiery, liquid mixture of minerals. 



Precious stones so formed would be colorless if, in the terrible fur- 

 nace of the primordial world, fire-proof metals had not taken upon them- 

 selves the task performed by aniline in our present dying-works. Long 

 before there were colored plants and animals, metals played the part 

 of pigments in Nature, and thus produced, in stones, colors almost 

 surpassing in brilliancy those to be found in the animal kingdom. 

 Rubies and emeralds are probably colored with chrome, sapphires with 

 cobalt, lapis-lazulis with iron, and other precious stones with copper, 

 nickel, manganese, etc. But we only have to refer our readers to the 



