Intercommunication / Answers: Making Lamp-Black. Standard Colors.

Manufacturer and Builder 6, 1871

[115] Making Lamp-Black. - There are so many modern methods of making lamp-black, and consequently, so many kinds of it, that it is impossible to give a correct account here. Our correspondent will have to wait for the full acoount in our series on paints, after that on the paints made of copper has been finished. We will only remark here that the main point of all methods is an imperfect combustion, under a defficient supply of air, in order to make as much smoke as possible. Only just air enough is admitted to prevent the fire from goin our. The smoke is passed into large brick chambers to cool and deposit the carbon, which is afterward collected in great quantities. Among the materials used are resin, coal-tar, petroleum, refuse matter from the petroleum distilleries, wood, bituminous coal, peat, etc.

[121] Standard Colors. - There are only three primary colors, red, yellow, and blue. The mixture of red and yellow gives orange; of yellow and blue, green; and of blue and red, violet; these are called secondary colors. The rainbow possesses them all in the greatest degree of purity. If, however, you mean by standard colors those used by painters to mix their pigments, then there are many kinds of each of the primary colors used; for instance, for red: vermillion, carmine, Paris red, burnt sienna, etc.; for yellow: ochre, raw sienna, chrome, and cadmium, etc.; for blue: ultra-marine, Preussian blue, cobalt, etc.; all primary colors, but of different tone. Black is no color, and seldom never used in color painting pictures. White is more used in oil-painting than any other pigment. In water-color, however, white is seldom used, as the white paper is sufficient for the lightest tones, if the paint is only put on thin enough. White being a reflection of almost all the luminous waves, and black an almost total absence of all reflection, neither of the two are colors in the proper sense of the word.