Hi Momber, and welcome to the forum!
The first page of One Night in Shanghai
is reproduced in The Art of Hergé, Volume 2
, by Phillipe Goddin, translated by Michael Farr.
Here's an Amazon link to it, if you're not familiar with the book:http://www.amazon.co.uk/Art-Herge-Vol-2-Philippe-Goddin/dp/0867197242/ ref=sr_1_1?ie=UTF8&s=books&qid=1275138746&sr=1-1
According to the book's caption text, this first page was the only page ever produced. The book also shows single panels from two other one-page demos of different adventure strip ideas produced by Hergé and Jacobs under their joint post-war pseudonym, Olaf (or Olav; I forget which and don't have the book in front of me!)
I think the pages were shown to a few publishers, but weren't taken on. And shortly afterwards, Hergé and Jacobs were given permission to work again, under their own names, thanks to the intervention of Raymond Le Blanc and his Tintin Magazine idea.
The single page of One Night in Shanghai
borrows many elements of The Blue Lotus, but is drawn in a more American noir style, a bit like Jacobs' most loose and sketchy style.
By the way, I believe the Art of Hergé series is basically a translated and abridged version of Phillipe Goddin's more extensive muti-volume Chronologie
series, so presumably this page also apears in the relevant volume of that.