Page:Proceedings of the Royal Society of London Vol 60.djvu/158

Rh Univalent Metals.

Refraction of the Elements and their Chemical Equivalents. 143 Metal. Specific refraction. f Combining proportion. Product. Lithium............. 0-514 2-65 1 -36 Sodium .. .« .. • • 0-202 4-80 0-97 Potassium .. . • •. 0-205 6-25 1-28 Rubidium ...... 0 133 9-24 1-23 Silver ».............. 0-121 10-3 1-26 OffisiUTU - - .......... 0-117 11 -5 1-35 . . - Mercury < • •. 0-107 14-1 1-51 Thallium 0 -106 14-3 1-51

This confirms the conclusions drawn in 1877, the mean product for the univalent metals, omitting sodium, being 1*30. This is in spite of the fact that lithium and caesium differ from one another in either factor in the ratio of about 9 to 2. The two metals below the line, though acting as monads in the compounds from which these values are deduced, are considered to be dyad and triad respectively. With them, the product is a little higher; this will be referred to afterwards.

Bivalent Metals. Metal. Specific refraction. V Combining proportion. Product. Beryllium.......... 0-733 2-12 1-55 Magnesium........ Calcium............. 0-287 0-252 3- 49 4- 47 1 -oo 1-12 Zinc,................... 0 151 5-71 0-87 Strontium ...... 0 -152 6-62 1-00 Cadmium.......... Barium............. 0-124 0-117 7*41 8-29 0-92 0-97 Mercury ........... 0-099 10 -o 0-99? Copper................ 0-184 5-64 1-04 Cobalt............... 0-183 5 -45 1-00 Nickel............... 0-186 5-42 1-01 Manganese ..... Iron............... ... 0-208 0*209 5-24 5-29 1-09 1-11 Lead................... 0-119 10-17 1-21 Tin..................... 0-232 7-71 1-78 Palladium......... 0-213 7 -30 1-55 With the exception of beryllium, those metals which are properly bivalent agree closely, although giving values distinctly below that of the former list. The mean of the values is 0*99. The remaining five metals, which have well-marked higher valencies, have, as in the case of the corresponding univalent elements, a somewhat highest value.