SA wrote:
> As I understand it, Vol. 3 of Capital was edited by
> Engels on the basis of Marx's notes and published in
> 1894. So do we know more or less in what period Marx
> wrote those notes?
The manuscript that forms the basis for Vol. 3 is actually the chronologically *oldest* of the manuscripts for the three volumes. So in that sense, it is theoretically not up to the level of the monetary theory of value developed by Marx in chapter one of Vol. 1. This raises a lot of interesting problems/questions concerning issues such as, for example, the "transformation problem", since the idea of a conversion of value into production prices seems a bit incompatible with a conception of abstract labor as a "real abstraction" consummated in exchange.
There is an older article by Michael Heinrich in _Science & Society_ that deals with Engels' editorship of Vol. 3:
http://www.oekonomiekritik.de/303Engels%20Edition%20Engl.htm