Infra-red absorption spectra of a series of concentrated aqueous solutions of sulphuric acid have been obtained in the region of cu. 290 to 4000cm-1. Certain observed absorption maxima are in close agreement with reported Raman frequency shifts. In the range of compositions studied, some bands have been attributed to HS04 ion and others to the HzSO~ molecule. Provisional vibrational frequency assignments have been made for those species. The free energy function and entropy for an ideal gas composed of H2SO4 molecules has been estimated at 1 atm and 298-15°K. LIn 1906, Pfund 1 obtained infra-red reflection spectra of dilute oIeum solutions and of concentrated aqueous solutions of sulphuric acid in the spectral range of cu. 800 to 2500 cm-1. Other spectral regions, e.g., 32 to 435 cm-1,66 to 192 cm-1, and 1540 to 5900 cm-1 were investigated later by Rubens,2 by Cartwright,3 and by Plyler and Barr4 for the concentrated and dilute acid ranges. Recently, Marcus and Fresco 5 obtained an infra-red absorption spectrum of 99.9 % sulphuric acid at frequencies of from cu. 700 to 4OOO cm-1.Pfund observed reflection maxima at 881, 966, 1042, 1163 and 1389cm-1 while Marcus and Fresco found absorption bands at 903, 967, 1171, 1364, 2430 and 3000 cm-1. Pfund's 1163 and 1389 cm-1 maxima are only in fair agreement with the corresponding ones of Marcus and Fresco, but the frequency values for the 966m-1 band are the same within experimental error. Pfund failed to observe the maximum at 903cm-1 and the bands which he found at 881 and 1042 cm-1 apparently are produced by HS04 ion.

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A spectrophotometric method for determining the concentration of chromium in oriented and unoriented single ruby crystals is described. It makes use of the absorption coefficients for the blue and green bands and for the red lines at ∼300°K. The coefficients are based on concentration data obtained by three independent methods.

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Quartz has been synthesized under hydrothermal conditions at rates of 1.78 mm/day in the presence of LiNO(2) in Ag lined and Ag plated systems, and it is shown that such quartz has optical transmission between 1500 A and 3 micro equal, and in some cases superior to, natural quartz. The uv cutoff at about 1500 A has been shown to be associated with Fe whose concentration may be reduced by procedures that reduce the concentration of charge compensating H+ in the lattice (growth in LiNO(2)) and by procedures which reduce the concentration of Fe in solutions (inert conditions). Transmission near 3 micro is affected by OH which can be reduced by LiNO(2).