Astonishing letter from CASANOVA to Prince Charles of Courland (husband of Countess Francoise Krasinska).
"MY LORD,—I hope your highness will either burn this letter after reading it, or else preserve it with the greatest care. It will be better, however, to make a copy in cypher, and to burn the original. My attachment to you is not my only motive in writing; I confess my interest is equally concerned. Allow me to say that I do not wish your highness to esteem me alone for any qualities you may have observed in me; I wish you to become my debtor by the inestimable secret I am going to confide to you. This secret relates to the making of gold, the only thing of which your highness stands in need. If you had been miserly by nature you would be rich now; but you are generous, and will be poor all your days if you do not make use of my secret.
"Your highness told me at Riga that you would like me to give you the secret by which I transmuted iron into copper; I never did so, but now I shall teach you how to make a much more marvellous transmutation. I should point out to you, however, that you are not at present in a suitable place for the operation, although all the materials are easily procurable. The operation necessitates my presence for the construction of a furnace, and for the great care necessary, far the least mistake will spoil all. The transmutation of Mars is an easy and merely mechanical process, but that of gold is philosophical in the highest degree. The gold produced will be equal to that used in the Venetian sequins. You must reflect, my lord, that I am giving you information which will permit you to dispense with me, and you must also reflect that I am confiding to you my life and my liberty.
"The step I am taking should insure your life-long protection, and should raise you above that prejudice which is entertained against the general mass of alchemists. My vanity would be wounded if you refuse to distinguish me from the common herd of operators. All I ask you is that you will wait till we meet before undertaking the process. You cannot do it by yourself, and if you employ any other person but myself, you will betray the secret. I must tell you that, using the same materials, and by the addition of mercury and nitre, I made the tree of projection for the Marchioness d'Urfe and the Princess of Anhalt. Zerbst calculated the profit as fifty per cent. My fortune would have been made long ago, if I had found a prince with the control of a mint whom I could trust. Your character enables me to confide in you. However, we will come to the point.
"You must take four ounces of good silver, dissolve in aqua fortis, precipitate secundum artem with copper, then wash in lukewarm water to separate the acids; dry, mix with half an ounce of sal ammoniac, and place in a suitable vessel. Afterwards you must take a pound of alum, a pound of Hungary crystals, four ounces of verdigris, four ounces of cinnabar, and two ounces of sulphur. Pulverise and mix, and place in a retort of such size that the above matters will only half fill it. This retort must be placed over a furnace with four draughts, for the heat must be raised to the fourth degree. At first your fire must be slow so as to extract the gross phlegm of the matter, and when the spirit begins to appear, place the receiver under the retort, and Luna with the ammoniac salts will appear in it. All the joinings must be luted with the Philosophical Luting, and as the spirit comes, so regulate your furnace, but do not let it pass the third degree of heat.
"So soon as the sublimation begins then boldly open your forth vent, but take heed that that which is sublimed pass not into the receiver where is your Luna, and so you must shut, the mouth of the retort closely, and keep it so for twenty-four hours, and then take off your fastenings, and allow the distillation to go on. Then you must increase your fire so that the spirits may pass, over, until the matter in the retort is quite desiccated. After this operation has been performed three times, then you shall see, the gold appear in the retort. Then draw it forth and melt it, adding your corpus perfectum. Melt with it two ounces of gold, then lay it in water, and you shall find four ounces of pure gold.
"Such my lord, is the gold mine for your mint of Mitau, by which, with the assistance of a manager and four men, you can assure yourself a revenue of a thousand ducats a week, and double, and quadruple that sum, if your highness chooses to increase the men and the furnaces. I ask your highness to make me your manager. But remember it must be a State secret, so burn this letter, and if your highness would give me any reward in advance, I only ask you to give me your affection and esteem. I shall be happy if I have reason to believe that my master will also be my friend. My life, which this letter places in your power, is ever at your service, and I know not what I shall do if I ever have cause to repent having disclosed my secret. I have the honour to be, etc."