At night a practice was used that was very wasteful of coals, the piling up of stone and coals 4ft high or more on the kiln tops, which are left to flame out to waste, instead of men working at night and supplying the kilns at proper intervals. Mr. Oldknow told me, that such piled part of the Lime, when burnt, was found much the whitest: I cannot, however, but consider it a great waste of fuel. An account by John Farey, Sen. 1813.
Perhaps Oldknow, being the man he was, "whitest", was a reference to the precious time (night) that he thought husbands (men worked the kilns) should have with their wives and children who had worked all day at the mill. This leniancy may have encouraged the men to work harder and of course procreate children for the next generation of workers.