Geometrical illustrations of Newlands' and Mendelejeff's periodic law of the atomic weights of the chemical elements / by Samuel Haughton.

  • Haughton, Samuel.
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: Geometrical illustrations of Newlands' and Mendelejeff's periodic law of the atomic weights of the chemical elements / by Samuel Haughton. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    16/20 (page 92)
    If we use the atomic weights and valencies of these nine elements (taking scandium = 44’3), we can find the equation of the cubic passing through these points, the form of which I have plotted in Plate vin., and which has one real asymptote like the former cubic, hut has a much more complex shape.1 The dyad lines, both positive and negative, have a remarkable relation to the cubic curve. They are both very near the position of the horizontal tangent. In fact, the positive dyad line intersects the cubic in three real points, viz.:— 79, 65-064, 65. The first of these is the element selenium, and the third the element zinc, with another element almost identical with zinc in atomic weight, both points being nearly on the horizontal tangent. The negative dyad line intersects the cubic in three real points also, viz.:— 40, 52, 56; which represent exactly the atomic weights of the three elements— calcium, chromium, and iron. How, we must remember that the cubic curve was constructed without any reference to iron, or its atomic weight, and it is very remarkable to find it taking its place on the curve after chromium, and near nickel and cohalt, which are not far off the dyad line. In fact, the cubic curve points out, by clinging to the dyad line, from 52 to 59, the possibility of forming, in that interval, a number of elements similar to each other in physical and chemical properties. These elements have been actually formed, and are— Chromium, Iron, Nickel, Cobalt. Excepting these four elements formed on the cubic branch of the curve, the distribution of the remaining elements, between the lineal and cubic branches, is similar to that found in the curve described in Part I. The first three elements are on the cubic, viz.— K | Ca | Sc. The last three elements are also on the cubic branch, viz.— As | Se | Br. 1 I venture to call it a serpentine ‘whiplash’ cubic.