Philosophical Transactions/Volume 12/Number 137/A Relation of the making of Ceruse
FIrst Pigs of clean and soft Lead are cast into thin Plates a yard long, six inches broad, and to the thickness of the back of a Knife. These are rolled, with some Art, round; but so as the Surfaces no where meet to touch: for where they do no Ceruss grows.
Thus roll'd, they are put each in a Pot just capable to hold one, upheld by a little Bar from the bottom, that it come not to touch the Vinegar, which is put into each Pot, to effect the conversion.
Next a square Bed is made of new Horse-dung, so big as to hold 20 Pots abreast, and so to make up the number of 400 in one Bed.
Then each Pot is covered with a Plate of Lead; and lastly all with Boards, as close as conveniently can be. This repeated four times, makes one heap, so called, containing 1600 Pots.
After three Weeks the Pots are taken up, the Plates unrolled, laid upon a Board, and beaten with Battle-dores till all the Flakes come off. Which, if good, prove thick, hard and weighty: if otherwise, fuffy and light; or sometimes black and burn'd, if the Dung prove not well order'd: and sometimes there will be none.
From the Beating-Table the Flakes are carried to the Mill; and with Water ground between Millstones, until they be brought to almost an inpalpable fineness. After which it is moulded into smaller parcels, and exposed to the Sun to dry till it be hard and so fit for use.
The Accidents to the Work are,
That two Pots alike ordered, and set one by the other, without any possible distinction of advantage, shall yield, the one thick and good Flakes, the other few, and small or none: which happeneth in greater quantities, even over whole Beds sometimes.
Sometimes the Pots are taken up all dry, and so sometimes prove best; sometimes again they are taken up wet. Whether this ariseth from the Vapors coming from below, or the moisture that is squeezed out by the weight of the Pots, we cannot discern.
This we observe, That the Plates that cover the Pots, yield better and thicker Flakes, than do the Rolls within. And the outsides, next to the Planks, bigger and better than the insides, next to the Rolls, and the Spirits that first arise out of the Vinegar.
We therefore question much, Whether the strongest bodied Vinegar, or the quickest and sharpest, be the most effectual?
The Accidents to the Workmen are,
Immediate pain in the Stomack, with exceeding Contorsions in the Guts, and Costiveness that yields not to Catharticks, hardly to often repeated Clysters: best to Lenitives, Oil of Olives, or Strong new Wort. It brings them also to acute Fevers, and great Asthma's or Shortness of Breath. And these we find effected principally by the Mineral Steams in the casting of the Plates of Lead, and by the Dust of the Flakes. Also by the Steams coming from out of the Heaps, when the Pots are taking up.
Next, a Vertigo, or dizziness in the Head, with continual great pain in the Brows, Blindness, Stupidity, and Paralytick Affections; loss of Appetite, Sickness, and frequent Vomitings, generally of sincere Phlegm, sometimes mixed with Choler, to the extreamest weakning of the Body. And these chiefly in them that have the charge of Grinding, and over the Drying Place.