Spectrographic methods, which are much less time-consuming than the usual chemical m ethods, are described for the determination of sodium, potassium, and lithium in portland cement. For the determination of sodium and potassium the sample is mixed with a mineral base containing silver for the internal standard. For lithium a standard mixture of graphite and strontium carbonate is added to the cement sample. In either case a fixed amount of the resultant mixture is placed in the crater of a graphi te electrode, which is made the lower positive element of a direct-current arc. The Na 8194.81 A, K 7698.98 A, and Li 3232.61 A lines are used for the quantitative calculations. A discussion of the development. of the method is given, followed by details of the adopted analytical procedure. The spectrographic analyses of 41 cements for sodium and potassium are given for comparison with the chemical values. CONTENTS Page
IRA-401 resins in their hydroxide forms can be used, but not the more highly cross-linked Dowex I-X8 or Amberlite IRA-400 resins, which yielded incomplete recovery of the acids. This is in direct contrast to the work of Robb and Westbrook (2) and Hornstein, et al. ( 5) who used in their experiments. No reason for this difference can be offered; however, we recommend the less highly cross-linked resins.Robb and Westbrook suggested that any other solvent capable of dissolving the tetramethylammonium salts could be used in place of methanol. However, chlorinated solvents such as chloroform and carbon tetrachloride when used alone or when present as minor components inhibit complete methylation of the acids. Actually, chloroform when used as a (5) I.
Time-intensity plots of Si, Fe, Ti II, Cu, and Li lines using 0.25-inch cupped electrodes containing different proportions of sample and admixtures.____._-_____-____-___-___-34. Time-intensity plots of Si, Fe, Ti II, Cu, and Li lines using deep-bore electrode No. 2 (bore depth 0.75 inch) containing different proportions of sample and admixtures._________ 35. Gas jet for 0.25-inch-diameter cupped electrode. A, Photograph showing electrode; B, diagram showing jet parts in exploded view._______._._._.____.____.__.__..._____-_ 241 36. Photograph of gas jet for 0.125-inch-diameter deep-bore constant-feed electrode shown in position on arc stand. ______ 37. Diagram of gas jet shown in figure 36 mounted directly on optical bench_______________________________________ 243 38. Spectra obtained from a G-1:LUB4Of. graphite mixture arced in atmospheres of COg, Ar-Og, and He-Og gases using deepbore electrodes-______________________________________ 244 39. Water-cooled gas jet used with deep-bore constant-feed electrode No. 3. A, Photograph showing ceramic cup of figure 36 replaced by brass collar; B, diagrams of top and side views. 246 40. Time-intensity plots of several elements using a gas-cooled and water-cooled jet with deep-bore constant-feed electrode No. 3._____________.
Viscosity Studies of Dickite Susflensions 289 behave somewhat differently in the Plastograph.These bodies show a sharp drop in plastic consistency with only a slight increase in water content, possibly caused by the organic electrolytes in the black ball clay; unfortunately no PH measurements were made on these bodies.Bodies Nos. 1 and 6, containing only china clays, show a very low plastic range. The dry strength of these trial bodies is the lowest of the series, and the grain-size distribution curve shows these bodies to be quite coarse.Bodies Nos. 7 and 8 have a quite similar composition, except that 2% bentonite was added to body No. 8. The effect is shown by an increased plasticity value and a higher percentage of fine grains below 1 micron.
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