Date: 29 Tevet 5595
From: Rabbi Moshe Sofer
To: Rabbi Yaakov
The responsum discusses the permissibility of a dairy pot placed in an oven where meat was roasting, with the meat fat dripping nearby but not directly onto the pot, analyzing the views of the Shach and Taz on the concept of 'mefa'pe'a' (percolation) and 'shnei kedeirot nog'in' (two pots touching).
Source: Shu"t Chasam Sofer CM §206