Fleta minor the laws of art and nature, in knowing, judging, assaying, fining, refining and inlarging the bodies of confin'd metals : in two parts : the first contains assays of Lazarus Erckern, chief prover, or assay-master general of the empire of Germany, in V. books, orinally written by him in the Teutonick language and now translated into English ; the second contains essays on metallick words, as a dictionary to many pleasing discourses, by Sir John Pettus ... ; illustrated with 44 sculptures.

CHAP. IX. How to make the raw Lees richer before the boyling▪

[Section. 1] * 1.1AFTER this way many Salt Peter boy∣lers have searched, but the true Method (because they have not been guided by the little Proof) they could not find; but thus it is to be done. Take a Tub full of the Lees (of which a Centner

contains four pound of Salt-Petre) pour it upon new Earth, let it stand upon it near 12 houres, that it may run off and as much as remains behind of the Lees, so much Water pour upon the Earth, and let it run through to the other, and thus you will receive so much again, as you had of Lees before; now when this is done, then prove the Lees, through the little Proof, so you will find (because of the other pouring over) it will contain 6 pounds, this 6 pounds of Lees, prove again upon fresh Earth, and let it stand 6 hours, and then run it off, and follow it with so much Water as remains behind upon the Earth; also that the first measure of Lees may come only again and not more, then the Lee will contain nine pounds, this you may once more pour over fresh Earth, and enrich it; but always observe, that the Lees may be neither more or less then it was at the first; and to follow this with Water in this manner, I only mention for the proof sake, that one may be sure of the enriching, for the Lees by this means will contain more Salt-Petre, and yet the Lees will not increase; then to supply the first measure of Lees, pour in some of the weak Lees, so it will be the sooner and more enriched, and of such you may then soon come to a Suds.

And though there is much labour and dilligence thus [Section. 2] to enrich the Lees, yet it comes all again, for one may * 1.2make in one Week two or three times more Salt-Petre▪ and it spends no more Wood, only it requires more Ves∣sels to keep the Lees severally for their enriching.

I will also shew hovv the Salt-Petre boyling may be [Section. 3] ordered to profit, first observe, because there appertains much of Earth to a great Boyl-work, and good Earth is not alvvays to be had, but sometimes, if one cannot prove the Earth, very poor Earth is mingled amongst it, that the expences are spent upon the poor as the good, and thereby no gain to be expected, therefore I judge it

more profitable to make the Boyl-work vvith three or four Tubs, that one may take the best Earth which is to be had out of old Cities, Houses and Stables, yet not too deep, by vvhich means such Lees as are of 8 pounds content, may easily be enriched (as above) to 18 or 20 pounds, and not done vvith so much boyling, this they may consider of, especially vvhere Wood is dear.

[Section. 4] * 1.3When the Lees is thus enriched, there vvill remain more Salt-Petre in the Earth (for the good Lees cannot take it all out) then upon this Earth pour common wa∣ter, let it stand some hours and then run it off, so you will receive weak Lees, prove it, and make the enrich∣ing thus, as hath been shewed, and so you may be con∣tinually at your work.

[Section. 5] * 1.4Now because the Salt-Petre Lees may be enriched out of poor Earth (much more the Allum Lees out of the same Oar and Earth) and may be boyled to better profit, vvill by dilligent searching, be found hovv it may be performed.

[Section. 6] * 1.5After this manner I judge one may make Lees on all roasted Oars, and try vvhat Salt they may yield, for I do believe that the roasted Lead Oars are not vvithout such a salty matter, which I leave to farther Experience; But how a Salt-Petre Halls, Houses or Sheds, are seen to be on the out-sides, you will see in the following Sculp∣ture, thus

[illustration]

Deciphered.

• 1. The fore-part of the Salt-Petre House, wherein the Lee Tubs do stand.
• 2. The back part wherein the Kettle and the Oven do stand, wherein the Salt-Petre is to be boyled.
• 3. The Old Pieces of dig'd Earth, out of which Salt-Petre is to be taken.
• 4. The Wood used for boyling it.

[illustration]

• 5. The Servant that shaves and fits the pieces of Earth, for boyling, 5. 5. 5.

Sculpture XLI.

It is also to be observed, That the Salt-Petre Sheds must be built very low, as possible, and covered with Straw, whereby the warmth from the Kettle may go over the Tubs, especially in Winter, (if Earth is to be had for boyling) so that the weak Lees may not freeze.

Notes

• * 1.1

  The manner of doing it.
• * 1.2

  The profit.
• * 1.3

  To water out the Earth.
• * 1.4

  To enrich Lees of Al∣lum.
• * 1.5

  Salts of Oars.