Re -diezejs where n and b are conelants. carefully studied.
I53
Tlie effects of aiinealitig and wire drawing are
H.T.B. Notes on the measurements of some standard resistances. R. T.Giaze-
brook. Phil.M a g . [ 51 5 0 , qro (1900). - The paper includes a descriptioii of four niethods which may be used to compare inultiples of a unit resistance, and a t the Same time includes some observations showing the order of accuracy atH. T.B. tained .
The genesis of the ions in the discharge of electricity through gases. J . J . Uzowtson. Phil.iVax. [j]50, 27s (1900).- In the case of the discharge of electricity .through a gas, tlie ioniLation produced results from the motion through the gas of ions or corpuscles already present. Under tlie influence of the electric field, velocity and kinetic energy is imparted to the ions which when reaching a certain, or as the author calls critical value, produces fresh ions by the%ollision of the ions with surrounding molecules. This dissociation goes on increasing, giving rise to an increasing nunlber of fresh ions until the conductivity of the gas rises to such a value as to reducc the strength of the electric field to the critical value, or the point where each ion produces but one successor. This beautifully explains the fact that it requires a field of definite streiigth to send a discharge tlirougli a gas, for it sliows that tlie electric field must be over the critical value ill order to produce ions over arid above the sniall number initially present. An explariation is also given of the fact that the current between two electrodes increases with their distance apart within certain limits, For with a distance coniparable with the niean free path of an ion the chances of collision and the productioti of fresh ioiis will be reduced ; hence with increasing distance the iiutiiber of collisions increases. The phenorrienon of striated discharge tlirougli rarefied gas is also one ininiediately explained in the light of the views set forth so clearly in the present paper. H. I(: 6.
Considerations regarding the theory of electrons. W. AI. 01-1.. Phil. Mag. [ 51 5 0 , 269 ( I F ) - Coiisidering the theory of electrons as developed by barmor, the author attempts to esplaiu by an illustrative model the machinery bringing about the mobility of the electrons, tlie question of " free niobility ' I as given being considered by 1,artrior as oiie of the fundaniental postulates, A short niatiiematical aiialysis, modified by Larnior, is given bearing on the theory, showing that the assumptions made do not account for attractiotis or repulsions between electrons without including '' free niobility ". N.7..D . The dissociation constants of very weak acids. J . Walkeranil UT Cormnck. Jour. Chem. Soc. 7 7 , 5 ( r 9 w ) .- A n apparatus was devised i n which solutions of gaseous acids could be diluted to definite strengths without being in comniunication with air. The following (libsociation constants (multiplied by 10~;) are given : acetic acid, rSoooo ; carbonic acid, 3 q o ; hydrogen sulphide, 570 ; boric acid, 1 7 : liydrocyanic acid, 1 3 ; phenol, 1.3. These correspond to the following percentage dissociations in decinormal solution : acetic acid, 1.3 ; carbonic acid, o 173 ; hydrogen sulphide, 0.075 ; boric acid, 0.013 ; hydrocyanic acid. 0.01 I ; phenol, o 0037. The conductivity of the water 0:7 x 1 0 - 6 mercury units was allowed for on the assumption that it was clue to carbonic acid as impurity. W. D.B.
