A study was made of the Raman spectrum of sulphuric acid at concentrations varying every five percent from 100 to 5 percent by volume. A dispersion of 10A/mm at 4200A and 15A/mm at 4500A was used. Eight lines were found, which varied gradually in frequency, width, and intensity with changing concentration. Their frequency ranges are 408–432, 561–596, 913–895, 970–973, 980–983, 1031–1051, 1142–1174, 1216–1236, 1352–1332. A gradual change in frequency with concentration was found for a number of the lines. The measurements were checked with a microphotometer.

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Procedures and inexpensive apparatus are described for photographing and projecting patterns formed by crystals in convergent polarized light. The methods are especially suitable for wide-angle patterns such as those formed by mica. Illustrations are given.

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