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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1922 Excerpt:...worked out the following explanation:--The most effective frequency v for ionising a gas is given by hv = eV, where h is Planck's constant, e the electronic charge, and V is the ionisation potential. Taking this as 9 volts (Frank and Hertz) the frequency v works out to give a wave-length A = 1380, thus agreeing very well with the value 1350 given by Allen (' Photo-electricity,' p. 90). But the energy required to move a charge e to infinity is of the form e2/&r where k is the dielectric constant of the medium and r the radius of the molecule. The most effective wavelength in a medium of dielectric constant k will be k times that in ozone itself, whose dielectric constant is nearly unity. The refractive index of linen was found to be approximately 1-53, and since k = /x.2 the dielectric constant of linen is 234. This value gives for the region of the spectrum that should be most destructive, a wave-length A. = 3230 in good agreement with the observed results. We now mention some contributions to the discussion of the nature of the equilibrium connoted by the term oxycellulose. OXYCELLULOSE. W. D. Bancroft and R. H. Currie (J. Phys. Chem., Io. 9, 159) The authors prepared a number of oxycelluloses by the usual methods and state that qualitatively they are similar substances whatever the method used. They all dissolve partially with a yellow colour in alkaline hydroxides and the residue is considered to be unchanged cellulose. The authors were never able to convert the whole of the cellulose to this soluble oxycellulose in one treatment and question whether 'pure' oxycellulose has ever been prepared. The a-oxycellulose of Nastjukoff (1901) is thus regarded as merely unchanged cellulose, the /J-(alkali-soluble) and y-(water-soluble) fractions are the same su...