Spectrochemical Determination of Silicon, Iron, and Aluminum in Mineral Powders with a High Voltage Direct Current Arc*1

Spectrographic Determination of Silica

“…The upper or counter electrode was shaped with a flat end, and the lower or supporting electrode was a center-post crater type having a crater x/4 inch deep. A machine similar to that described by Oshry, Ballard, and Schrenk (8) was used to shape and bore the electrodes.…”

“…The significance of the age of precipitating solutions seems to have been overlooked by the many investigators (8) who have studied the factors affecting the particle size of analytical precipitates. However, Bancroft (1) stated that, in his opinion, the number of nuclei present in solution is more important than the extent of supersaturation as proposed by von Weimarn (8).…”

“…Nickel oxide was used as a buffer by Oshry, Ballard, and Schrenk (8), and cupric oxide by Jaycox (6); a mixture of barium nitrate and ammonium sulfate was reported by Fitz and Murray (1); beryllium carbonate in a mixture with sodium chloride was used by Kvalheim (7). Herdle and Wolthorn (4) used silica, the major constituent of the sample, as the internal standard in analyzing silica refractories for .the other elements, and then determined silica by difference.…”

Quantitative Spectrochemical Analysis of Ashes, Deposits, Liquids, and Miscellaneous Samples

“…Emulsion Calibration. Where emulsion calibration in terms of relative intensities is required, it is calibrated by means of a step sector, step filter, or the two-line method of Churchill (8).…”

Metallic Contaminants in Fluid Cracking Catalyst

“…Spectrographic methods have been applied (3,5,6) to the analysis of various minerals and ores. A method has been described (7) for the analysis of silica-alumina catalyst for contaminants in which lines of silicon and aluminum are used for reference; empirical factors are introduced to compensate for the differences of film emulsion response of the separate spectral regions of the film.…”