CYANIDE OR SIMPLE CYANURET OF POTASSIUM.
Before entering into the preparation of this ingredient, I may mention that the prussiate of potash of commerce has, by many young experimentalists, been mistaken for the above article, because it is often sold, by those unacquainted with chemical technicalities, under the name of cyanuret of potassium. It is, in chemical parlance, termed ferro-cyanuret, from its containing a certain portion of iron; and differs in its properties, very materially, from the simple salt. It is of a bright yellow color, and is converted into the colorless, simple cyanuret in the following manner:
Take 4 ounces of the yellow prussiate, break it in small pieces, and well dry it on a plate of iron; then reduce it in a mortar to exceedingly fine powder. Dry and pound in like manner one and a-half oz. of carbonate of potash. Incorporate the two ingredients thoroughly. Place a Hessian crucible in the fire; and when it attains a red heat, throw into it the prepared mixture, and closely cover the crucible. Keep up the heat, and the contents of the crucible will soon fuse; and the fluid mass will become red-hot. After this, immerse in it, from time to time, a hot glass rod; the mass which adheres, is in the early stages of the process brown on cooling; as the heat is continued, it appears yellowish, and finally, colorless and transparent. The operation is then complete: the crucible must be removed; and after its contents have been allowed to settle, the fused mass may be poured off; the greater portion of which consists of the simple cyanuret of potassium. This salt is very deliquescent, and must therefore be retained in close bottles: it will readily be recognized by its powerful odor,—that noticed in peach blossoms. The mere mention of prussic acid entering largely into its composition, will be sufficient to induce my reader to exercise common caution in handling it.
Having these ingredients prepared, take one pint of pure rain or distilled water; add to it two ounces of the cyanuret of potassium, shake them together occasionally, until the latter is entirely dissolved; and allow the liquid to become clear. Then add a quarter of an ounce of oxide of silver, which will very speedily dissolve; the dissolution may be hastened by heat, and after a short time, a clear transparent solution will be obtained.—Walker.
STEREO-CHROMIC PAINTING.
A new mode of fresco painting, called Stereo-chromie, which has for a long time excited attention among the artists of Germany, has it appears been perfected by a pupil of Kaulbach, in his own studio in Munich. The design is Kaulbach's, and the work was executed under his superintendence. It represents the figure and character of a Prophet, and will be sent to the London Exhibition. 'The figure, grand and majestic as it really is, cannot be expected to convey to the English public anything but a faint idea of the genius and skill of Kaulbach,' but as a specimen of this new and wonderful mode of painting, it will be regarded, by artists, with the greatest curiosity.
Stereo-chromie was discovered by Obergrath von Fuchs, a distinguished chemist; and is considered by German artists as one of the greatest discoveries of the age. They claim for it great advantage over ordinary fresco and encaustic painting, in its superior durability and the power which it affords the artist of retouching and glazing his picture. The colors are mixed with water, the whole being permanently fixed by occasional sprinklings of water, in which a certain proportion of fluoric-acid (Flassspath saurs) is mixed.
Stereo-chromie is in fact a preserver of the wall on which it is painted, By a certain chemical action of the solution sprinkled over the picture, while in progress, the whole ground on which it is placed, and the picture itself becomes one hard flinty mass, the very colors of which are converted into the hardest stone.
This singular species of painting resists, it is said, every influence of climate; and may be securely used as an external coating for buildings in any part of the globe. Neither is the artist confined to any particular time in executing it, leaving off when he pleases and for any length of time. In these points it is a most important recommendation, which cannot by any means apply to fresco work, nor, except within certain limits, to oil painting. The highest advantage of all, however, is that the same part may be painted over as often as the artist please, which is impossible in fresco; and consequently the most perfect harmony may, by this new mode be preserved throughout the largest possible painting. In fresco the artist is the slave of his materials; here, he is the arbitrary master and to the fullest extent.—Banner of the Union, Pa.