In his Treatise on Poisons (1832), Robert Christison defers to Braid’s occupational safety knowledge,
and reports Braid's view that systematic ventilation (including high chimneys) in smelting workshops significantly reduces lead-poisoning (p.506). From personal contact ("for I am informed by Mr Braid"), he cites Braid as an authority when emphatically stating that, whilst lead miners are liable to all sorts of occupational disease, they do not get lead poisoning because "the metals are not poisonous until oxidated", and that only those exposed to the fumes of the smelting furnaces succumb. (Christison (p.496) was eager to correct the widely held (erroneous) notion that all workers at the lead mines – namely, both "those who dig and pulverise the ore" and "those who roast the ore" — were equally likely to succumb.)
The mine operators paid one in every six bars of lead, as rent, to Lord Hopetoun; and the average number of bars produced was around 18,000 each year (Chambers & Chambers, "Leadhills", (1844), p.701).
