430 
proporties of the elements, si nee ai most all important physica! pro- 
porties are periodic functions of their atomic weights. 
By plotting Dkwars’s values of specifie heat at about 50° absolute, 
we get a clistinct periodic curve ; evidently at about 50° absolute, 
Fig. 4. 
specifie heat, like other physical properties of elements, is a periodic 
function of the atomic weight of the elements. The alkali metals, 
lithium, sodium, potassium, rubidium, caesium etc. lie on a straight 
line at the top of the curve. The halogen elements lie on a straight 
line on the ascending portion of the curve itear the alkali metals, 
on the descending portion nearing the alkali metals lie Mg, Ca, Sr 
etc. S, Se and Te may be connected by a straight line. So also Zn, 
Cd and Hg. The platinum metals, (Osmium, iridium, platinum, 
ruthenium, rhodium, and palladium) lie on the minima of the curves. 
Coëfficiënt of linear expansion. The researches of Fizeau show 
that the volatile elements occurring in the ascending curve possess, 
almost without exception, a larger coëfficiënt of expansion by heat 
between 0° and 100° than the not easily fusible elements occupying 
the minimum of Lothar Meyer’s curve. 
Similar vague suggestions are collected in Lothar Meyer’s “Theories 
of Chemistry” Eng. Trans. p. 131 from the works of Carnelly 
(Journ. Chem. Soc. J879, 565); Wiebe (Ber. 1878, 2289; 1880, 
1258); Raoxjl Pictet (Compt. rend. 1879 LXXXVIIÏ, 855) on the 
