Hello I hope someone can help. I have seen an individual listed on the 1881 census in Philipston, Scotland (near Glasgow), whose occupation is listed as: "Retort". I have some reason to believe that the individual in question might have had something to do with shale minining/processing. Can anyone tell me what a "Retort" is, or what someone whose occupation is a "retort" does. Does it have anything to do with shale mining? Many thanks. Douglas