As someone who has been researching the Schultze Gunpowder Company, I am interested to read your posts about the connection in the USA.
The precise location of the original UK factory was in the New Forest, Hampshire quite near to where I live. Information on the company is rather sparse and I believe all their London addresses were sales offices. You may be interested in a web page that I wrote for a website that I manage - http://www.newforestvrs.org.uk/forest-history/schultze-factory/