They provide a _Kettle_ or a _Caldron_, but a _Caldron_ is more proper, such an one as is described in Plate 9. at m. This Vessel should hold twice so much _Oyl_ as they intend to _Boyl_, that the _Scum_ may be some considerable time a _Rising_ from the top of the _Oyl_ to the top of the Vessel to prevent danger. This _Caldron_ hath a Copper Cover to fit the Mouth of it, and this Cover hath an Handle at the top of it to take it off and put it on by. This _Caldron_ is set upon a good strong Iron _Trevet_, and fill’d half full of old _Linseed-Oyl_, the older the better, and hath a good Fire made under it of solid matter, either _Sea Coal_, _Charcoal_ or pretty big Chumps of Wood that will burn well without much Flame; for should the Flame rise too high, and the _Oyl_ be very hot at the taking off the Cover of the _Caldron_, the fume of the _Oyl_ might be apt to take Fire at the Flame, and endanger the loss of the _Oyl_ and Firing the House: Thus they let _Oyl_ heat in the _Caldron_ till they think it is Boyling-hot; which to know, they peel the outer Films of an _Oynion_ off it, and prick the _Oynion_ fast upon the end of a small long Stick, and so put it into the heating _Oyl_: If it be Boyling-hot, or almost Boyling-hot, the _Oynion_ will put the _Oyl_ into a Fermentation, so that a Scum will gather on the top of the _Oyl_, and rise by degrees, and that more or less according as it is more or less Hot: But if it be so very Hot that the Scum rises apace, they quickly take the _Oynion_ out, and by degrees the Scum will fall. But if the _Oyl_ be Hot enough, and they intend to put any _Rosin_ in, the quantity is to every Gallon of _Oyl_ half a Pound, or rarely a whole Pound. The _Rosin_ they beat small in a _Mortar_, and with an Iron Ladle, or else by an Handful at a time strew it in gently into the _Oyl_ lest it make the Scum rise too fast; but every Ladle-full or Handful they put in so leasurely after one another, that the first must be wholly dissolv’d before they put any more in; for else the Scum will Rise too fast, as aforesaid: So that you may perceive a great care is to keep the Scum down: For if it Boyl over into the Fire never so little, the whole Body of _Oyl_ will take Fire immediately. If the _Oyl_ be Hot enough to _Burn_, they _Burn_ it, and that so often till it be _Hard_ enough, which sometimes is six, seven, eight times, or more. To _Burn_ it they take a long small Stick, or double up half a Sheet of Paper, and light one end to set Fire to the _Oyl_; It will presently Take if the _Oyl_ be Hot enough, if not, they Boyl it longer, till it be.