In correcting a typographical error (160 bars should read 750 bars, on p. 393) in a previously published paper on tectonic, petrologic, and physicochemical aspects of granite, additional comments are made on the role of pressure and temperature in determining the viscosity of pitchstone and the more widespread occurrence of ignimbritic rocks, which would be the expected result of a gas-dispersed magma. The Precambrian porphyries in central Sweden described by von Eckermann in 1936 and recently shown by Hjelmqvist to be ignimbritic are used as an example.

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