Travels Through Italy; In the Years 1771 and 1772

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1776 Excerpt: ...brim are dug into the hot bottom of the Solfatara. The subterraneous heat makes it boil; and, to strengthen-the aluminous water, they put large pieces of hard aluminous rocks into it. Being sufficiently evaporated, they mix some urine or pot-ashes into it, in order to take away the superfluous acid, and then put it, without any percolation, to crystallize in small round tubs. That is the whole manipulation pulation of making alum at the Solfatara. The lead-pans last for a hundred years and more. There is in some parts of Solfatara some native green iron-vitriol, but in no considerable quantity. If they exposed to the acid steams of Solfatara iron-filings, or the iron-sand, which is ib common on the shore from Naples to Pozzuolo, they would probably produce larger quantities of iron-vitriol, and at a cheaper rate. By a similar operation they might produce copper-vitriol by copper-filings. S'elemte is found on the inclosing walls of Solfatara, either in undetermined lumps or formed like stalactites. Being often grown in feather-like fibres, ignorant Mineralogists call it alumen plumosum., u In former times they gathered the sulphur-flowers or lumps from the surface of the clay-heaps accumulated near the steaming fissures, and distilled them in earthen retorts, which they had sent from Rome; but, the operations being too expensive, they have dropt it. Small crystals of red arsenic, native sulphur, and alum, do likewise sublimate on the surface of these clay-heaps or the inclosing walls, either in small lumps or lamelles, and many different small crys ' talline forms. There There is at present but a single artificial hole in the floor, ) where they gather salmiac, in the following manner: They cover this hole with loose fragments of broken pots and tiles, in whi..