THOSE inventions are deserving of special honor, and generally receive the most substantial recognition, which develop new industries or utilize waste products.
The glycerine industry, which has attained colossal proportions, is a notable illustration of a great manufacture based entirely upon the saving of what until lately was a waste product of the soap-boiler. As even more important, I may mention the industries connected with the manufacture of aniline dyes and artificial madder from the refuse coal-tar that was formerly the curse and nuisance of the gas-works. Old boots and shoes and leather waste are turned to good account by the chemical manufacturer in producing the cyanides, ferro and ferrid cyanides, so indispensable in color-printing and photography. Of the carcasses of slaughtered animals, not a scrap or morsel is allowed to go to waste, as you are well aware; and even the waste blood of the abattoir is used by the sugar-refiner and the manufacturer of albumen. Sawdust mixed with blood, or some other agglutinative substance, and compressed by powerful pressure in heated dies, is formed into door-knobs, hardware and furniture trimmings, buttons, and a thousand useful and decorative articles; or, as is the case with the spent bark of the tanneries, it is utilized for fuel under steam-boilers. Oyster-shells, of which our barbarous progenitors of ages ago made the shell-mounds that delight the soul of the anthropologist of to-day, are burned to lime; the waste of the linseed-oil manufacturers is eagerly sought after as food for cattle; the waste ashes of wood-fires are leached for potash; river-mud is mingled with chalk, and burned and ground to
- An address delivered at the opening of the spring course of lectures of the Wagner Free Institute of Science, Philadelphia, March 1, 1879.