McKenna Process Company
Plant formerly located in Joliet, Illinois - ca. 1920.
Photographs in the Denver Public Library
Visit to Denver, Colorado - 1932

Notes on viewing the linked photographs.  The images can only be obtained with a secondary site search, and you can repeat that search with the search terms listed in the column at right.
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Langford house in Black Hawk, Colorado - three images
Langford
Langford iron works in Black Hawk, Colorado - one image
Langford
Henry Hanington the senior - portrait
Hannington[sic]
Hanington cottage at Grand Lake, Colorado - three images
Hannington[sic]
Charles H. Hanington's photographs of the Boston and Colorado Smelting Company's Argo Smelting Works, in Denver, Colorado.   Descriptions below are quoted from the data provided with the images.  See also this link.
Hanington
      Three and a half tons pure silver $85,000.
same
      Brick covered furnace and chimney, shovel, mallet, hoppers.
same
      Chimney surrounded by gutters emanating from a furnace.
same
      William Beynon stands next to a cart with furnace, crucibles, and chain hoists.
same
      Ino George, with shovel, and Jack O'Conner with brick covered furnace and chimney, with hoppers, troughs.
same
      Ino George, with shovel, and Charles Johnson with brick covered furnace and chimney with hopper.
same
      Construction of a brick chimney with wood scaffolding, barrels, building materials.
same
      Brick covered furnace with attached troughs, and a hopper-1892.
same
      Brick covered furnace and chimney, hoppers, troughs.
same
      Row of round, wood tanks and rectangular containers.
same
     Stack of crucibles on top of a furnace, a hoist, and a cart.
same
     Studio portrait of Henry Hanington, a senior at Denver High School in Denver, Colorado, 1889.
same
     Charles Harrington Hanington, 1617 Champa St., Denver, Colorado - 1887 - no image, but corroborates George, Senior's Hanington address.
same