NEW ENGLAND FARMER. 



279 



it was practiced by a Mr. Bird, a stone cutter, at 

 Oxford, although his method is not recorded. More 

 subsequently Mr. Robert Chambers, of Minchin- 

 hampton, in Gloucestershire, (Eng.) discovered 

 and practiced a method of staining marble of va- 

 rious colors, which he called a secret. The colors 

 were so well and intimately combined with the 

 marble, that Da Costa, who tried many experi- 

 ments on several specimens of marble stained by 

 this artist, found it impossible to remove them even 

 by boiling in a strong alkaline solution. Since 

 then the art has been known and practiced by many 

 as a secret, which has proved to those engaged in 

 it a very lucrative employment. Kircher, we be- 

 lieve, was the first writer that has given publicity 

 to any thing practicable in regard to the operation. 

 Meeting with stones in some cabinets supposed to 

 be natural, but with figures so peculiar and nice as 

 to lead him to wonder at their beauty and form, he 

 was led to examine them more particularly, and 

 found that not only the surface, but the whole 

 thickness was perforated by the colors. He at 

 once suspected the truth, and sought out the person 

 who executed the work, and endeavored to learn 

 from him tlie secret. This he could not obtain on 

 any terms, as the artist considered the secret too 

 valuable to part with on any conditions. Foiled in 

 this attempt, he at once, with a Saxon named Gun- 

 ter, by numerous experiments, succeeded in pro- 

 ducing the same results. They used aqua-fortis 

 and aqua-regia and sal ammoniac, two ounces of 

 each of the two former, and one ounce of the lat- 

 ter, together with two drams spirits of wine, 

 twenty-six grains of gold and two drams of pure 

 silver. They calcined the silver, put it in a glass 

 vessel and poured the aquafortis upon it, and the 

 mixture left to evaporate. The gold was put into 

 another vessel, aqua-regia poured upon it, and 

 when dissolved this mixture was also evaporated. 

 Next, the spirits of wine was put upon the sal 

 ammoniac and evaporated in the same manner. 

 After evaporation the remainder or coloring matter 

 of the several mixtures, which was about the con- 

 sistence of paint, was applied without the consis- 

 tence of heat, by tracing the figures with a pencil 

 on the marble, the several parts being touched over 

 with the proper colors. This operation was re- 

 newed daily until they had penetrated to the de- 

 sired depth into the stone. The block or mass, 

 after being thus prepared, may be cut into thin 

 slabs or plates, all of which will have the perfect 

 representation of the figure or form delineated on 

 the surface, as the colors do not spread as they 

 penetrate the block. The most beautiful method 

 of staining by this procress is to apply the colors 

 to each slab separately, on the back, and not per- 

 • mit them to penetrate entirely through the stone, 

 but just deep enough to be seen through the sur- 

 face on the front after being polished, which pro- 

 cess, if skilfully performed, is exceedingly beau- 

 tiful, and most perfectly resembles veins of delicate 

 color in the natural stone. 



The most common method now practiced, how- 

 ever, is by means of heat to open the pores of the 

 marble so as to render it better fitted to receive the 

 colors. Marble of the hardest kind is to be se- 

 lected, perfectly free from seams or veins, and very 

 finely polished. This is heated to a degree just 

 suflleient to make the staining color boil on its sur- 

 face. The solvents used to strike in the colors 

 must be varied according to the color to be used. 



For a blue, stone blue is dissolved in spirits of 

 wine, for a bright red, vermillion dissolved in the 

 same, for a darker shade still finely powdered coch- 

 ineal may be used ; also dragon's blood and a tinc- 

 ture of logwood for the darkest shades. A fine 

 color is also obtained from alkanet root used with 

 oil of turpentine, as alcohol will not mix with this 

 substance. 



The staining of marble to any degree of red or 

 yellow may be produced by dragon's blood or gam- 

 boge, reduced to powder and ground with spirits of 

 wine in a glass mortar, and the tincture applied to 

 the stone with a pencil. These tracings will, on 

 heating the marble, penetrate very deep and remain 

 perfectly distinct. A slight tincture of dragon's 

 blood alone, without heat, will be sufficient to pro- 

 duce a pale flesh color, which for some purposes is 

 very desirable. If a very deep or intense color is 

 required a little pitch added to the tincture gives it 

 the desired effect. This art is one of peculiar 

 nicety, and when properly executed is exceedingly 

 beautiful, and may be varied or extended to almost 

 any degree by those who become adepts in the 

 business. — Farmer and Mechanic. 



IMPROVEMENT IN THE MANUFAC- 

 TURE OF STEEL. 



The London Mechanic's Magazine records an 

 improvement of lilwald Riepe, of Finsbury Square, 

 in refining steel. For this purpose he takes bars 

 or lumps of raw or crude steel (particularly pud- 

 dle steel,) and in order to the refining of them, pla- 

 ces them in a furnace or other heating chamber, 

 out of the reach of any injurious action upon them 

 by the atmospheric air, and there subjects them 

 for a time to a temperature not exceeding the melt- 

 ing point of steel. I use for the purpose a weld- 

 ing furnace, such as is ordinarily employed in pud- 

 dling iron, only that the bed is lowered and the 

 grate brought from two to four feet below the level 

 of the fire-bridge, and the ash-pit is provided with 

 an iron door, by which it may be entirely closed 

 when required. When the furnace is in full heat, 

 I place the bars or lumps of raw or crude steel on 

 the bed of the furnace, but at distances apart, so 

 that they may nowhere touch each other; and dur- 

 ing the whole of the refining process, the fire-place 

 is kept fully charged with coals or other fuel. Then, 

 in order to exclude as much as may be the access 

 of oxygen, I carefully lute any crevices there may 

 be, in the working door or elsewhere, with wet 

 clay, and so regulate the draught of the furnace 

 by means of the ash-pit door and flue-damper — clos- 

 ing them more ot less, or altogether, as may be 

 requisite — that the heat shall never attain to the 

 melting point of steel. A sufficient practical test 

 of this is furnished by the color of the flame, which 

 is, with this view, carefully watched through an 

 eyehole in the working door. As long as it keeps 

 of a dull or hardly red color, the heat will not be 

 in excess of what is required. I usually put from 

 GOO lbs. to 3,000 lbs. of raw or crude steel, in bars 

 of 3 inches by 1 1-2 inches, into a furnace of the 

 ordinary size, and continue the operation for about 

 four hours. By this method of operation, car- 

 buretted hydrogen and oxide of carbon are devel- 

 oped in the furnace in abundance, while the oxy- 

 gen of the atmospheric air is entirely prevented 

 from acting on the steel; and the product is sieel 

 of a very fine uniform grain. 



