SCIENCE IN THE INDUSTRIAL WORLD 



important are ultramarine, Prussian blue, and cobalt 

 blue. 



The pigment ultramarine, as used by the ancients, 

 was literally "worth more than its weight in gold," 

 as was said a few pages back. For this pigment was 

 made by grinding to powder the semi-precious stone, 

 lapis lazuli, found only in China, Siberia, and Persia. 

 Its cost, therefore, placed it outside the realm of com- 

 mercial pigments; and only the opulent among the 

 artists could afford to use it. It was made by grinding 

 the mineral to a fine powder, mixing this with a com- 

 pound of resin, wax, and linseed oil, and kneading the 

 mixture in a bag immersed in hot water. The blue 

 color comes through the cloth into the water and finally 

 settles. It is a tedious process of ancient origin, and yet 

 no simpler or better method has ever been discovered 

 for making the ultramarine pigment from the mineral. 



Even if such a method had been discovered, the pig- 

 ment would still have been far too expensive for general 

 use, owing to the cost of lapis lazuli itself. But early 

 in the nineteenth century, when the infant science of 

 chemistry was doing so much to solve the hitherto elu- 

 sive riddles of Nature, practical chemists effected the 

 analysis of the mineral ultramarine with a view to its 

 artificial production. The day of great triumphs of 

 analytical and synthetic chemistry had just dawned, 

 and one of the first was the production of an artificial 

 ultramarine product superior in quality to the natural, 

 and costing less than a thousandth part as much. 



Analysis had shown ultramarine to be largely a com- 

 pound of the common substances, silica, aluminum, 



[296] 



