Carl A. Wrote:
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> About 5:18, there's a bit of movie of something
> being sprayed. I'm guessing it was weedkiller. Are
> there other ideas?
You are correct.
There were several different companies that contracted with the railroads to provide weed control spraying. One of those companies was Nalco Chemical Company ("Nalco") and if the below link works, the photo shows one of their trains spraying on the Burlington in Illinois.
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www.flickr.com]
Each railroad provided their own locomotive and caboose, operating crew, and perhaps a representative from Maintenance of Way. Nalco provided the cars and chemicals, and the employees to operate them.