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Boiled Oil for Varnishes

Mix equally good if the turpentine be added just 100 gallons linseed oil and 7 pounds calcined before the mixture becomes too cold to permit white vitriol (sulphate of zinc) in fine powder, of a perfect amalgamation. In fact, it is now in a clean copper boiler; heat it to 2850 Fahr., acknowledged that the oil need not be raised and keep it at that temperature for at least an hour, constantly stirring it; then allow it to cool; in 24 hours decant the clear portion, and in 3 or 4 weeks rack it for use. 2873. Cautions Respecting the Making of Varnish. As heat in many cases is necessary to dissolve the gums used in making varnish, the best way, when practicable, is to use a sand-bath, which is simply placing to a higher temperature than that at which the gum employed fuses, and that when the two are mixed the lowest possible degree of heat which will insure their incorporation, is sufficient to secure all the results desired. By this method a large quantity of the turpentine formerly lost in evaporation is saved, and there is, moreover, less risk of fire. The heating vessel must be of copper, of a capacity at the vessel containing the varnish, in another least one-third more gallons than the mixture filled with sand and placed on the fire. This to be introduced into it, with a riveted and will generally be sufficient to prevent the not a soldered bottom. To promote the adspirits catching fire; but to avoid such an ac- mixture of the copal with the hot oil, the cocident (which not unfrequently happens), it pal-carefully selected and of nearly uniform will be best to take a vessel sufficiently large fusibility-is separately heated with continto prevent any danger of spilling its contents; uous stirring over a moderate charcoal fire indeed, the vessel should never be more than kept constantly supplied with fuel, without OIL VARNISHES. disturbing the kettle until the completion of 2879. Amber Varnish. Amber, 1 the mixture with the oil. If the copal is melt- pound; pale boiled oil, 10 ounces; turpentine, ed in the hot oil, the resulting varnish is more 1 pint. Render the amber, placed in an iron colored and less drying. There is, however, pot, semi-liquid by heat; then add the oil, great care required in fusing the copal by it- mix, remove it from the fire, and, when cooled self; for if the heat is too much prolonged, a little, stir in the turpentine. Or: To the the resin becomes pitchy, and gives an inferior varnish. Constant stirring is requisite to prevent adhesion to the sides and bottom of the vessel, and consequent scorching. The pieces of copal should be of uniform fusibility; the different varieties, therefore, should not be fused together, for that which melts first is apt to scorch before the more refractory are color. It dries well, and is very hard and amber, melted as above, add 2 ounces of shellac, and proceed as before. This varnish is rather dark, but remarkably tough. The first form is the best. It is used for the same purposes as copal varnish, and forms an excellent article for covering wood, or any other substance not of a white or very pale fused. If it is desired to mix different varie- durable. ties, they should be fused separately and then Ammixed in fluid state. When the resin is thor- ber, 1 pound; boiled oil, 1/2 pint; powdered oughly melted, the hot oil is to be ladled in asphaltum, 6 ounces; oil of turpentine, 1 gradually during constant stirring. To deter- pint. Melt the amber, as before described, mine when sufficient oil has been added, a then add the asphaltum, previously mixed drop must be now and then taken out and with the cold oil, and afterwards heated very