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Die kolorimetrische Bestimmung geringer Mengen von Gold. Von RALPH NEL~OW MAX SON.^ Anwendungen der kolorimetrischen Methode fiir die Bestimmung geringer Goldmengen , basiert auf Bildung von Cassius Purpur, sind vorgeschlagen worden von CAILNOT 2, ROSE s, SONSTADT ' , CASSEL~, PRISTER~, MOIR~ u. a.; doch sind diesen Verfahren verschiedenen Einwanden ausgesetzt. Nach den Angaben anderer Chemiker wechselt die gedachte Fjirbung auberordentlich in Intensitit und Ton, je nach den Verhiiltnissen der Losung und des Fiillungsmittels; uberdies ist die Substanz nicht stabil, und kunstliche Standlosungen sind erforderlich, wenn genaue Resultate erzielt werden sollen. Es ist nun die Vermutung ausgesprochen worden, dafs die F i b u n g der roten kolloidalen Goldlosungen in quantitativer Beziehung zu der vorhandenen Metallmenge stande und demnach fur eine kolorimetrische Bestimmungsmethode benutzt werden konnte, die von den erwiihnten Fehlern frei ist. Es wurde deswegen die folgende Untersuchung unternommen, um festzustellen, ob jene roten Kolloide nicht ein geeignetes Mittel zur Bestimmung geringer Mengen von Gold waren. Zuerst handelte es sich naturlich um die Darstellung der roten kolloidalen Losungen. BLAKE~ hat gezeigt, d d s Acetylen das beste Ins Deutsche iibertragen von J. HOPPEL. Compt. r d. 97, 105. 169. Chena. News 66, 271. ' C h. Nms 26, 159.
This paper gives an account of the early niter and gunpowder industry in Kentucky and is largely based upon a memoir written in 1806 by Dr. Samuel Brown of the Medical Department of Transylvania University.A description of the process used to obtain potassium nitrate, from the cave earths and sandstone rocks, is accompanied by a discussion of Dr. Brown's theories offered to explain the chemistry of the process and the origin of the deposits. Some suggestions, based on modern geology and chemistry, are proposed to explain the process and certain theories are advanced to account for the nitrate deposits.The geology of the cavern and rock house region is discussed briefly.One of the important needs in the early days of the Republic was an adequate domestic supply of saltpeter and a satisfactory grade of gunpowder.This question was indeed one of international interest. In 1776 France selected M. Lavoisier to be superintendent of the National Powder Works. Coleman was investigating the properties of charcoal in England,1 and thanks to his researches British powder was of superior quality. Bowles, Dillon, and Townshend had studied the Spanish niter deposits and the Indian supply was the subject of investigation. It is recorded that the Second Continental Congress encouraged the manufacture of saltpeter in the province by offering twenty pounds for every hundredweight that should be made.The defects of the powder made in the United States were well known to the scientists of the day, and the military forces had difficulty in obeying the injunction, "keep your powder dry," when deliquescent impurities nullified all their precautions. The state of Kentucky was especially interested in an adequate powder supply. In the early days her very existence depended upon the efficiency of the "long rifles," and in the first years of the new century approaching * Presented before the Division of History of Chemistry at the eighty-first meeting of the American Chemical Society, Indianapolis, Indiana, March 31, 1931.' Coleman, Phil. Mag. [5], 9, 355 (1801). 1847* Lexington was the seat of Transylvania University (now 151 years old) and this institution added a Medical Department in 1799.Dr. Samuel Brown was selected as the professor of chemistry, anatomy, and surgery in October of that year.Dr. Brown was born in Virginia in 1769 and died in Huntsville, Alabama, in 1830. He was a graduate of Carlisle College and studied medicine at the University of Edinburgh. He was an aggressive and versatile scientist and "to him we are indebted for the first introduction in the West of the prophylactic use of the cowpox." As early as 1802 he had vaccinated upward of 500 persons when New York and Philadelphia phy sicians were only just making their first experimental attempts.2
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