Lime

In times past, the hills and moors of Yorkshire and Cumbria were much more heavily populated and worked than they are now. There were mines (coal, lead), quarries and lime kilns, as well as farms and handloom weavers' cottages (and hand knitters in Dentdale). I was fascinated to come across this restored lime kiln in Dentdale, with its useful explanatory board - for a more complete explanation, see here. Lime was one of the goods ferried by train and on the canals from the Dales to the cities during the Industrial Revolution. It has a number of uses, in building and in agriculture.

The cellar in my house is white lime-washed - and the mortar in the stone walls is black lime mortar. Lime mortar is relatively soft, allowing some flexibility in the walls as the ground shifts and settles and it also allows the walls to breath and moisture to evaporate. It can cause problems in these old houses if you cover them over with modern mortar or render, leading to damp and cracking. Though the other problem is that, over time, the mortar degrades a bit and the black gritty dust creeps into the house, which isn't good news.