Antique book?

I just found a curious book.

"Manual of the National Union" printed by the Senate 1887

Evidently there's a "committee on secret work" or something too. It's basically a How-to manual of the National Union's proceedings.

I can't find anything about it through Google or the Library of Congress. The only mention of it online is on a Freemasonry website that says an older printing was used as reference for something.

Can anyone get more info on this? I'm at a complete loss. I can't even find a "National Union" that was active in 1887.

Well the report has something to do with fraternal organizations and insurance as well as rituals, rites, and ceremonies. Guessing, I'd have to say the National Union was a type fraternity but could very well be labor-union related seeing there was a bit of a surge in labor-union activity in the late nineteenth century.