A practical treatise on the manufacture of colors for painting : comprising the origin, definition, and classification of colors; the treatment of the raw materials .. etc. . edoperations. We have seen that the transformation of the cya-nide of ammonium into cyanide of potassium, andthen into ferrocyanide of potassium, is effected by theintermediation of the sulphate of iron. The only diffi-culty in the practical operation is to arrive at a com-plete absorption of the cyanide of ammonium in thesolution of sulphate of iron, and that without a strongpressure of gases, which not only impairs the
A practical treatise on the manufacture of colors for painting : comprising the origin, definition, and classification of colors; the treatment of the raw materials .. etc. . edoperations. We have seen that the transformation of the cya-nide of ammonium into cyanide of potassium, andthen into ferrocyanide of potassium, is effected by theintermediation of the sulphate of iron. The only diffi-culty in the practical operation is to arrive at a com-plete absorption of the cyanide of ammonium in thesolution of sulphate of iron, and that without a strongpressure of gases, which not only impairs the qualityof the bone black, but causes losses of a portion of thegases through leaks in the apparatus. The authoruses, for this purpose, apparatus which is very simpleand permits of regulating at will the rapidity of theoperation. Let us suppose a box, about 2 metres long, 216 MAXtJFACTURE OF COLORS. 60 centimetres wide, and 20 centimetres deep, in whichare placed four flat, shallow pans, 5 centimetres high,and pat one on top of the other in an inverted posi-tion (Fig. 47). On the bottom of each pan, towardsone of the ends, there is a narrow opening. The box is Fig. filled with the liquor, and the mixture of gases, which isintroduced below the first pan, expands until it gainsthe opening. It then passes into the second pan, and,in the same manner, into the third and fourth. Theo-retically speaking, there is constantly a layer of gases,of 4 X metres = square metres in area, incontact with the liquid, and the distance followed bythe gases is 4x 2 metres = 8 metres, under a pressureof only metre of water. The box is also providedwith a stopcock for removing the liquors, a funnelwhich dips a little below the level of the liquid, andan outlet pipe for the washed gases, which are after-wards burned under the fireplace. In order to pre-vent explosions the gases to be burned are made topass through a small box filled with fine metallic a precipitate take
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherphila, bookyear1874
