Page:The American Cyclopædia (1879) Volume II.djvu/41

 ASSAYING ASSEMANI 29 say of copper is performed by dissolving a weighed amount of ore in nitric acid, and re- moving sulphur if present by an addition of chlorate of potassium. Muriatic acid is added, and the nitric acid removed by evaporation. The residue is dissolved in water and muriatic acid and filtered; the copper is precipitated from this solution by pure zinc or iron, and the resulting copper sponge is washed by decant- ing the liquid and replacing it by distilled water, nd then quickly dried and weighed as metallic copper; from this weight the value of the ore is easily calculated. The dry assay of copper is still in use in Cornwall, at Swan- sea, and at some other places. It is, as con- ducted by metallurgists, often an empirical process, the fluxes being added with very vague ideas as to their true effect. The ores are prop- erly classified into those which contain no sul- phur, arsenic, or any foreign metals but iron ; those which contain sulphur, iron, arsenic, an- timony, &c. Ores of the first class, containing over 3 per cent, of copper, are reduced in a crucible by the addition of three parts of black flux. Poorer ores may be assayed in the wet way. The second class are sulphates or sul- phurets. The former are easily decomposed by heat in a platinum crucible, when they may be treated as substances of the first class. The sulphurets, under which general head are in- cluded most of the workable ores of commerce, are treated in a great variety of ways. The first operation, after reducing them to fine powder, is to roast or calcine them, to expel the sulphur. This process requires care and experience, and is most thoroughly effected, according to Mitchell, by adding one tenth of their weight of carbonate of ammonia to the roasting mass in the crucible, constantly stir- ring it in as the calcining goes on. Sulphate of copper is produced by the roasting ; and on addition of carbonate of ammonia, by double decomposition, sulphate of ammonia forms, which being volatile can be expelled by heat. The ore is then thoroughly mixed in a mortar with 25 per cent, of its original weight of lime, and 10 to 20 per cent, of fine charcoal, and 1J time its weight of dry carbonate of soda. The whole is to be placed in the same crucible in which the roasting was done, and covered with its weight of glass of borax. It is then sub- jected to a moderate heat for a quarter of un hour, and to a bright red heat as much longer. On cooling, and breaking the crucible, the button of copper will be found in the bot- tom. It is well to make two parallel assays of these ores, that one may confirm or dis- prove the other. The varieties of lead ores which are most commonly subjected to assay are the sulphurets (galena) and the carbonates. The former is treated by taking 400 or 500 grains, coarsely powdered, and mixing with it one fourth its weight of black flux, one fourth of iron nails, and one eighth of cream of tar- tar. The crucible should be large enough to contain double the quantity, and the charge should be covered with common salt half an inch deep. After being exposed to a high heat for ten minutes, the lead may bo poured out, or suffered to cool in the crucible. If the ore contain much earthy or pyritous matter, a less proportion of iron filings should be used, and a little fluor spar and borax be added. Galena j is conveniently assayed in an iron crucible, the crucible itself furnishing the material for desul- phurizing the ore. The usual quantity, say 400 or 500 grains, is mixed with 2 timesjts weight of carbonate of soda, and put in an iron crucible, which is covered. The galena is decomposed, and sulphuret of iron formed. The lead is poured out into an ingot mould, and the crucible well tapped to obtain all the lead. Another sample is immediately put in while the crucible is hot, and the operation repeated as long as the crucible lasts. The carbonates are assayed with half their weight of black flux, and a little cream of tartar, with a superficial covering of salt. ASSELYJf, Jan, a landscape painter, born in 1610, died in Amsterdam in 1660. He studied under Jan Miel and Isaiah Vandervelde at Antwerp, and under Peter van Laer (Bamboc- cio) at Rome. In his landscapes taken from the vicinity of Rome, which are enriched with ruins of edifices, and decorated with figures and cattle in the style of Berghem, he imitates the manner of Claude Lorraine. lie also paint- ed battle pieces of considerable merit. He was surnamed Jfralbetje (little crab, crab-like) by the Dutch artists at Rome, on account of a con- traction in his fingers. Asso AM. I. Joseph Simon, a Syrian oriental- ist, born at Tripoli (Tarablus) in 1087, died in Rome, Jan. 14, 1768. After spending many years in the study of eastern languages, he was employed to collect oriental manuscripts for the library of the Vatican, and finally appoint- ed custodian of the collection, which he large- ly increased. His principal works are : Biblio- theca Orientalis Clementine- Vaticana (Rome, 1719-'28); Kalendaria Ecclesia Universes (1755-'7); Bibliotheca Juris Orientalis Cano- nici et Ciuili* (1762-'4). He edited also an edition of the Opera Ephraemi Syri (1732-'46). II. Stephan Evodius, nephew of the preceding, born at Tripoli in 1707, died Nov. 24, 1782. Like his uncle he devoted himself to the study of oriental languages, and like him was made custodian of that department of the library of the Vatican, from which post he was ap- pointed archbishop of Apamea. His investi- gations among oriental manuscripts were em- bodied in his two works, Bibliotheece Mediceo- Laurentinas et Palatines Codices Manuscripts Orientales (Florence, 1742), and Acta Sanc- torum Martyrum Orientalium et Occidenta- lium (Rome, 1748). III. Joseph iloyslos, broth- er of the preceding, born at Tripoli about 1710, died in Rome, Feb. 9, 1782. Pursuing the same studies as his uncle and brother, he was appointed professor in the Sapienza at Rome. His works are : Codex Liturgicus Eccletia