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. . ust remain open, in orderto watch the operations, and to add fresh portions ofthe materials. These considerations show how diffi-cult it has been to prevent the losses by volatilization,and have caused us to search for the process whichwe are about to explain. Figs. 71 and 72 are vertical and horizontal sectionsof the apparatus for melting the resins or gum resins. a is the fireplace, placed below the floor of thework-roo
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. . ust remain open, in orderto watch the operations, and to add fresh portions ofthe materials. These considerations show how diffi-cult it has been to prevent the losses by volatilization,and have caused us to search for the process whichwe are about to explain. Figs. 71 and 72 are vertical and horizontal sectionsof the apparatus for melting the resins or gum resins. a is the fireplace, placed below the floor of thework-room as usual; h is the door of the fireplace?and c, the ash pit. Upon this fireplace there is placeda cast-iron kettle nearly filled with an alloy ofequal parts of lead and tin, because the melting pointof lead alone is too high for our purpose. The flamepasses through the flues e and f around the kettle: 618 APPENDIX. g is the melting pot, made of thin copper, and rivetedto the collar h. The pot is held in the bath by threeiron hooks ^, ^, % which pass into corresponding placescut in the collar h; and the fastening is effected bypartly turning the pot. Fig. n. Fig. On top of the pot there is a kind of hanging lip m,occupying one-half of the circumference, and stand-ing at about the distance of 12 millimetres from theinward surface of the pot. The opening thus left onthe side of the pot is covered with a riveted semi-circular conduit, which at n connects with the pipep _p\ The pipe jp^ is attached to a cooling worm,placed in a tub of cold water, and the outlet from theworm terminates in a vertical pipe, the lower part ofwhich is closed with a stopcock and receives the con-densed products, while the upper part is connectedwith an exhausting apparatus, which is constantlyaspiring the vapors into the cooling worm, and de-livers into the air the uncondensable products. Thefollowing is the manner of using the apparatus. When the fire is Hghted, and the metallic bath is OILS, VAKN
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Keywords: ., bookcentury1800, bookdecade1870, bookpublisherphila, bookyear1874
