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. . y for melting a charge, thetemperature of a considerable quantity of metaldoes not change sensibly, even should the fire be muchurged, or allowed to die out. Besides, an excess ofheat may be reduced immediately, by introducing alarge piece of cold iron through the opening r, andleaving it in the bath for one or two minutes. Ingeneral, we may feel confident that the temperaturewill remain constant during one operation, unl
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. . y for melting a charge, thetemperature of a considerable quantity of metaldoes not change sensibly, even should the fire be muchurged, or allowed to die out. Besides, an excess ofheat may be reduced immediately, by introducing alarge piece of cold iron through the opening r, andleaving it in the bath for one or two minutes. Ingeneral, we may feel confident that the temperaturewill remain constant during one operation, unless thefire be entirely neglected. When the resin is melted and mixed with oil, itshould be removed from the metallic bath into theboiling pot. The contents are poured from the side Thus, in this manner of melting resins, the heat hasbeen easily regulated without escaping fumes, andwith a condensation of volatile products, which maybe utilized advantageously by the varnish maker. 620 APPENDIX. Fig. 73 is a vertical section of the pot for boilingoils, gums, and resins in the manufacture of varnishes. The same pot may also be em-Fig. 73. j)loyed for boiling the oils em-. ployed in the preparation ofpaints. A, copper pot of the ordinaryshape; b, flat cast-iron pan,which is made very thick, in or-der to stand and retain the heat, and thus to counterbalance rapidchanges in the temperature of the fire. This pan iskept over the fireplace c, by means of the flange b b,which rests upon the brickwork d. The copper potis held upon the air bath, by means of the rivetedflanged ring a. The cover of the pot is an annularinverted gutter e, the curvature e^ of which has itsedge quite close to the sides of the pot, without, how-ever, touching them, and is connected by means of thetube H with a cooling worm and an exhaust. Themode of operation is as follows:— The heat of the fireplace o is transmitted to thepan B, and the air contained therein communicatesits temperature to the boiling pot, whi
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherphila, bookyear1874
