Two questions please.
(a) Can der eine in the following be replaced with einer?
(b) If yes, how is the meaning or nuance changed?
Karl stand eng ans Büfett gedrängt, denn kaum hatte er sich angestellt, war hinter ihm ein Tisch aufgestellt worden, und der eine der dort sich niederlassenden Gäste streifte schwer, wenn er sich nur ein wenig beim Reden zurückbog, mit seinem großen Hut Karls Rücken.
The sentence is from Kafka’s Der Verschollene (Amerika). For full text, please click this link for the Gutenberg page.
The thought expressed seems to be one of — i.e. an unrestricted member of a class. In English, the one would require something to restrict (distinguish from others) the member being picked out, as follows for example.
One of the guests brushed against Karl’s back.
The tallest one of the guests brushed against Karl’s back.
If German works the same way in general, but there was a special circumstance favoring der eine in the quoted sentence, it would be very helpful to know what that was. Thanks.