The Berlin luxury paper factory Heymann & Schmidt at Schönhauser Allee 164 was incorporated in a new company in 1904-5, producing calendars, postcards, posters, promotional items, greetings cards and packaging. The company also had some activites in Cologne. Many of the postcards, as common for chromo cards, were trade advertising cards. The company survived WW2 but printing activies ended around 1920-30.
The logo H&S in a box without the B occurs on cards posted in Austria, Hungary and Belgium and was maybe an export brand. I have presumed that the early card with plain H & S is also Heymann & Schmidt.
Where cards are very yellow or brown it is difficult to judge whether all of this is due to age or whether the original was on tinted card. For example H&S 295 may well have looked more like this originally: