Skip to main content
U.S. flag

An official website of the United States government

Articles

Browse more than 65,000 articles authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.

Filter Total Items: 74057

Radiocarbon activity of shells from living clams and snails

[No abstract available]
Authors
M. Rubin, D.W. Taylor

Radiogenic strontium-87 as an index of geologic processes

The abundance of radiogenic Sr87 relative to Sr86 at the time of crystallization has been determined for 45 rocks. The total range in the ratio Sr87/Sr86 is less than 2 percent. Ratios for recent lavas range from 0.702 to 0.711. Oceanic basalts are closely grouped at 0.703, whereas ratios for continental volcanic rocks spread from 0.702 to 0.711. Among the volcanic rocks, ranging from basalt to rh
Authors
C. E. Hedge, F.G. Walthall

Releasing-addition method for the flame-photometric determination of calcium in thermal waters

Study of the interferences of silica and sulfate in the flame-photometric determination of calcium in thermal waters has led to the development of a method requiring no prior chemical separations. The interference effects of silica, sulfate, potassium, sodium, aluminum, and phosphate are overcome by an addition technique coupled with the use of magnesium as a releasing agent.
Authors
J.J. Rowe

Some phases of the life history of the trout-perch

The trout-perch, Percopsis omiscomaycus (Walbaum), is one of the more abundant forage fishes in the larger lakes of midwestern United States and central Canada where walleye, Stizostedion v. vitreum (Mitchill), yellow perch, Perca flavescens (Mitchill), and coregonids predominate. It has been suggested that it may have considerable effect on perch and walleye populations of these lakes. The pres
Authors
John L. Magnuson, Lloyd L. Smith

Spectrophotometric determination of micro quantities of zinc in rocks

A chemical method is presented for the determination of microgram amounts of zinc in rocks. Zinc is absorbed on anion-exchange resin from 1.2 M hydrochloric acid and eluted with 0.01 M hydrochloric acid. A diethyldithiocarbamate separation removes traces of interfering elements from the eluate. The zinc-diethyldithiocarbamate complex is extracted into chloroform at pH 8.5 and reextracted from othe
Authors
C. Huffman, H. H. Lipp, L. F. Rader