I've looked and never found that alledged ad in AMAZING STORIES.
However, here are a couple of Siegel's listings for SCIENCE FICTION in trade publications.
From a 1932 issue of THE EDITOR:
...and from THE AUTHOR & JOURNALIST
Every time I see a Siegel piece of prose from this era, I admire how literate he was even at this (early) stage of his career.
Couple of questions:
Is the business regarding a water glass and silicic acid a specific "in-joke" of the period, or simply Siegel's imaginative way of discouraging additions to the slush pile?
and
Is the expression "radio the stories back" a slang expression back in the day that just means the item will be mailed back? From the context it was, but I'd love to know what the background of the evolution of the term is/was.