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ARTE DE LOS METALES
become too powerful and dense. Thus the air imprisone d in the receiver will be cooled, the gases will condense more quickly, and there will be less risk of breaking the vessels. When the Nitric Acid has been removed from the receiver, pour a little in a flask and on half a drachm of silver. When the silver is dissolved add a small amount of water; add more water, and in a short time the liquid, which at first appeared turbid, will become clear, and white sediment will fall to the bottom. Separate this sediment and save in another tightly stoppered flask or vial. When the vessels are cold, remove from the retort the calcined and exhausted residue remaining after distillatio n; if very hard, it is best to add water, to avoid the risk of breaking the retort, and heat moderate ly in order to dissolve and easily remove the material. I invented a kind of vessel for distilling Nitric Acid, which is so well adapted for this purpose that I have continued to use it, and have passed it on to my friends. The best vessels for these distillatio ns are long-necked glass retorts, because of the short travel for the fumes coming off from the materials ; they, however, are inconven ient on account of the difficulty of filling and emptying through the long and narrow neck. Make an imitation (of the foregoing) of good clay, and on top, before the clay dries, describe with a compass, and cut out, ĂĄ piece the size of a crown, large enough to admit the hand easily; place four protrudin g buttons or knobs equally distant around the circumference of the opening. Bake and glaze both the retort and the piece cut out, which is to serve as a lid. Charge the materials through this handhole , put on the lid, adjust and lute so that the vapours cannot escape, fasten the cover with a wire which passes diagonall y around the buttons, and connect to the neck. When the distillatio n is finished the materials can be removed with the greatest facility through the aforesaid openmg. FUNDACIĂ“N Jt.:ANELO TURRIANO