999 resultados para Prepusa montana


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The use of zinc as a structural metal has been militated against by two of its properties, namely, its low tensile strength and its susceptibility to grain growth. The importance of these factors can be appreciated when it is realized that the tensile strength of coarsely crystalline cast zinc is 4,000 pounds per square inch, while finely crystalline cast zinc has a tensile strength of 12,000 pounds per square inch.

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The field of archaeology and that of metallurgy appear to be widely separated and in no way related. Work done in recent years, however, tends to show that, in many ways, the metallurgist can supplement and enhance the information gain­ed by the archaeologist, at least in regard to those objects which have been made of metal.

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The formation of monomolecular films is possible because of the action of the heteropolar molecules of certain fatty acids, especially stearic. Under the proper conditions the acid will spread out until a monomolecular film is formed.

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A hydrometallurgical process for the recovery of copper from flotation concentrates has long been con­sidered an attractive possibility. The object of such a method is to produce electrolytic copper without resorting to expensive matte smelting and converting.

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Carbon and carbonaceous material have been known to have a deleterious effect upon the cyanidation of gold and silver ores since the very beginning of the process. Organic matter is a common source of impu­rities in cyanide solution, its reducing effect being notorious.

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Among the many aluminum alloys which have been studied are the binary copper-aluminum alloys. These have proven to be among the most useful of the alumi­num alloys thus far worked upon.

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It has been proven that cadmium forms a very satisfactory plate on steel, which has to withstand severe corrosion, especially the corrosion of sea water and spray. The metal is now successfully plated electrolytically from cyanide solutions, but wherever work is carried on with cyanide, there is great danger of poisoning to the workers.

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The purpose of this research was to continue the work of Thomas Parker, who worked on the recovery of copper and zinc from brass during the school year l934 - 1935. Since there is such a wide variety of brasses made with usually a third alloying constituent, remelt­ed scrap is suitable only for castings of wide tolerance in specifications.

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Since the development of cyanidation into a highly efficient process for treating gold ores, many papers have been written on its various aspects. Although, there has been much work done on it, the chemistry of the reaction is not yet completely understood.

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The tin alloys of tellurium are extremely hard and have very great tensile strength. It was thought that the reduction of the rate of grain growth of tin with the addition of tellurium accompanied this hardening and strengthening and such way found to be true.

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It is the purpose of this investigation to obtain some insight into optimum conditions for leaching Stib­nite with sodium hydroxide solution and also to steady the factors affecting the electrolysis of the resulting solution.

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In August 1977 excavation was conducted at the Big Creek Lake site -24RA34- at the outlet of the 91g Creek Lakes, Selway-Bitterroot Wilderness Area, Ravalli County, Montana. The site contained shallow, disturbed deposits and lacks any statisgraphic separation. One of these occupations was identified by a projectile point type not previously reported from the area. This was termed Big Creek Corner Notched and its temporal affiliation is not precisely known. Comparative material from Colorado and Alberta suggest either Early Archaic or Late Archaic affiliation. The occupations exemplified by Big Creek Corner Notched points and by Pelican Lake-Elko points (Late Archaic 1000 B.B – A.D. 200) were the most prevalent at the site. Less intensive occupations are by ·Middle Plains Archaic McKean points and Late Prehistoric small side notche arrow points. Microscopic analysis of tool working edges shows several of the projectile point forms were used as multi-functional implements. especially as butchering tools. Many of the types of chipped stone recovered from the site are from known sources in western Montana; indicating group movements within the eastern portion of the Intermountain region. Based on the numerous projectile points and cutting tools, the site is interpreted as a seasonally occupied base camp for hunters.

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Morrison Cave is located about 50 miles southeast of Butte, Montana. It was named after the man who discovered it. Later it was taken over by the State and renamed Morrison Cave State Park. Recently the government with the aid of the Civilian Conservation Corps has built a new road to the cave and has made the interior more accessible. The name of the cave is now Lewis and Clark Cavern National Monument.

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Agate in any of its varieties presents numerous problems in regard to its origin. Many types have been described and their beauty elaborated upon, but little has been written concerning their formation and the problems involved. The genesis of agate implicates an amazing complexity of physical and colloid­al chemistry, as well as, various principles of geology.

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The research described in this presentation is part of the Global Observation Research Initiative in Alpine Environments (GLORIA) whose purpose is to establish and maintain a global, long-term observation network in alpine environments. Despite changes in mountaintop-vegetation due to recent climate change being observed throughout the world, trends are not consistent. Moreover, as plant communities can be impacted by several different factors, it is important to be able to separate what is due to climate change and what is due to e.g. changes in grazing pressure (see additional file below).