Rays of positive electricity and their application to chemical analyses / [Sir J.J. Thomson].

  • Thomson, J. J. (Joseph John), 1856-1940.
Date:
1921
Catalogue details

Licence: In copyright

Credit: Rays of positive electricity and their application to chemical analyses / [Sir J.J. Thomson]. Source: Wellcome Collection.

    199/278 (page 183)
    mje has three times the value corresponding to the parabola A, and B will have a prolongation towards the vertical axis extending to one-third of the normal distance. For the purposes of Chemical Analysis it is not neces- sary to use the elaborate apparatus with appliances for measuring the electric and magnetic field. The more elaborate apparatus is only required when we require to know accurately the values of the quantities A and B which occur in the expression for ejtn> For the determination of the masses of the particles pro- ducing the different parabolas the measurement of the quan- tities A and B is unnecessary if we can recognize the particle which produces any particular parabola. For since A and B are the same for all the parabolas, then for any two parabolas we have by the equation on page 180— 2Ei y2*jx2 where (ejm)1 (e/m)2 are the values of e/m, for the particles pro- ducing the parabolas (1) and (2) respectively, (xxy^) (%y2) are the co-ordinates of any point on the first and second parabolas respectively. If the points on the two parabolas have the same values of x so that xx = x2 then (ejm) 1 _JTi2 y* if the charges are the same _ y? **1 yl As the line corresponding to the atom of hydrogen occurs on all the plates and can at once be recognized by being the most deflected line on the plate, the value of (ejm) for the particles producing any parabola can be at once, by the aid of