Page:Landscape Painting by Birge Harrison.djvu/160

LANDSCAPE PAINTING present extractdextracted [sic] by the oil trust, which, in order to secure a slightly increased output, subjects the seed under pressure to a high heat, with the result that in addition to the oil there is pressed out of the mash a variety of resins and essential oils, whose ultimate chemical effect on our colors we cannot as yet determine. Finally, the whole output is boiled with a certain addition of litharge to help its drying quality, and litharge is red lead. So here the lead equation enters into our palette again, in spite of our best efforts to exclude it. There are, however, I believe, two color-men in the world who, recognizing the necessity of pure raw oil for artist's use, have recently established plants of their own, where the seed is pressed cold and the oil is left raw. These firms are Bloch and Winsor & Newton. There may, of course, be [120]