plant 33

A battery of Birkeland-Eyde furnaces for the fixation of
nitrogen at the DuPont plant 33

Fixing nitrogen by calcium carbide 40

A barrow full of potash salts extracted from six tons of
green kelp by the government chemists 41

Nature's silent method of nitrogen fixation 41

In order to secure a new supply of potash salts the United
States Government set up an experimental plant at
Sutherland, California, for utilization of kelp 52

Overhead suction at the San Diego wharf pumping kelp
from the barge to the digestion tanks 53

The kelp harvester gathering the seaweed from the Pacific
Ocean 53

A battery of Koppers by-product coke-ovens at the plant
of the Bethlehem Steel Company, Sparrows Point,
Maryland 60

In these mixing vats at the Buffalo Works, aniline dyes
are prepared 61

A paper mill in action 120