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Geology topics

R.E. Stevens

Publications and source records attributed to R.E. Stevens.

13 recordsLinked to original sources
USGS2002

Determination of the common and rare alkalies in mineral analysis

Methods are described which afford a determination of each member of the alkali group and are successful in dealing with the quantities of the rare alkalies found in rocks and minerals. The procedures are relatively rapid and based chiefly on the use of chloroplatinic acid, absolute alcohol and ether, and ammonium sulfate. The percentages of all the alkalies found in a number of minerals are given.

Industrial And Engineering Chemistry Analytical Ed↗
USGS2002

Nephelometric determination of fluorine

Fluorine in minerals may be determined with the nephelometer to about 1 per cent of the fluorine. The determination is made on an aliquot of the sodium chloride solution of the fluorine, obtained by the Berzelius method of extraction. The fluorine is precipitated as colloidal calcium fluoride in alcoholic solution, gelatin serving as a protective colloid. Arsenates, sulfates, and phosphates, which interfere with the determination, must be removed.

Industrial And Engineering Chemistry Analytical Ed↗
USGS2002

Determination of thorium and of rare earth elements in cerium earth minerals and ores

The conventional oxalate method for precipitating thorium and the rare earth elements in acid solution exhibits definite solubilities of these elements. The present work was undertaken to establish conditions overcoming these solubilities and to find optimum conditions for precipitating thorium and the rare earth elements as hydroxides and sebacates. The investigations resulted in a reliable procedure applicable to samples in which the cerium group elements predominate. The oxalate precipitations are made from homogeneous solution at pH 2 by adding a prepared solution of anhydrous oxalic acid in methanol instead of the more expensive crystalline methyl oxalate. Calcium is added as a carrier. Quantitative precipitation of thorium and the rare earth elements is ascertained by further small additions of calcium to the supernatant liquid, until the added calcium precipitates as oxalate within 2 minutes. Calcium is removed by precipitating the hydroxides of thorium and rare earths at room temperature by adding ammonium hydroxide to pH > 10. Thorium is separated as the sebacate at pH 2.5, and the rare earths are precipitated with ammonium sebacate at pH 9. Maximum errors for combined weights of thorium and rare earth oxides on synthetic mixtures are ± 0.6 mg. Maximum error for separated thoria is ± 0.5 mg.

Analytical Chemistry↗
USGS2002

Determination of iron in the presence of chromium and titanium with the Jones reductor

Sulfuric acid solutions of titanous and chromous sulfates, obtained by passage through the Jones reductor, are oxidized by aeration for from 5 to 10 minutes in the presence of a trace of copper sulfate as a catalyst. Ferrous sulfate is essentially unoxidized and is titrated with permanganate after aeration. Best results are obtained by using 0.0003 millimole of copper sulfate in about 300 ml. of solution. Larger quantities of copper sulfate lead to slightly low results when both chromium and titanium are present.

Industrial and Engineering Chemistry↗
USGS1962

Summary of new data on rock samples G-1 and W-1

Published and unpublished analyses for major and minor constituents that have become available since April, 1960, are collected for the granite G-1 and diabase W-1. “Best values” are suggested for some of the elements.

Geochimica et Cosmochimica Acta↗
USGS1958

Apparatus and technique for multiple tests by the confined-spot method of colorimetric analysis: Application to field estimation of nickel and copper

The confined-spot method of colorimetric analysis is generally applicable to the semiquantitative estimation of traces of ions in solution that form colored precipitates or otherwise alter material on a confined area of reagent paper. For precise results, the rate of flow of test solutions through the reagent paper must be reproduced on successive runs, so that the same proportion of reaction products is collected each time on the confined spot. A simple apparatus gives a controlled rate of flow and makes possible the analysis of many samples at one time with good reproducibility. This apparatus utilizes the increasing pull, resulting from the gradual lowering of the water level in a tank, to draw a sample solution through a confined area of reagent paper at a reproducible rate. Application to the rapid determination of nickel with dimethylglyoxime and of copper with rubeanic acid provides a method for determination of as little as 0.06 γ of nickel and 0.03 γ of copper. The coefficients of variation are 14 and 22%, respectively. This method has wide applicability in more rapid and convenient determination of trace amounts of many metals.

Analytical Chemistry↗
USGS1956

Machine for preparing phosphors for the fluorimetric determination of uranium

The time saved by use of a machine for preparing many phosphors at one time increases the rate of productivity of the fluorimetric method for determining uranium. The machine prepares 18 phosphors at a time and eliminates the tedious and time-consuming step of preparing them by hand, while improving the precision of the method in some localities. The machine consists of a ring burner over which the platinum dishes, containing uranium and flux, are rotated. By placing the machine in an inclined position the molten flux comes into contact with all surfaces within th dish as the dishes rotate over the flame. Precision is improved because the heating and cooling conditions are the same for each of the 18 phosphors in one run as well as for successive runs.

Trace Elements Investigations↗