Hydrogen Lanthanum Titanium Silicon
Sodium Niobium Manganese Strontium
Nickel Palladium Chromium Barium
Magnesium Neodymium Cobalt Aluminum (4)
Cobalt Copper Carbon (200 or more) Cadmium
Silicon Zinc Vanadium Rhodium
Aluminum Cadmium Zirconium Erbium
Titanium Cerium Cerium Zinc
Chromium Glucinum Calcium (75 or more) Copper (2)
Manganese Germanium Scandium Silver (2)
Strontium Rhodium Neodymium Glucinum (2)
Vanadium Silver Lanthanum Germanium
Barium Tin Yttrium Tin
Carbon Lead Niobium Lead (1)
Scandium Erbium Molybdenum Potassium (1)
Yttrium Potassium Palladium

_Doubtful Elements_.

Iridium, osmium, platinum, ruthenium, tantalum, thorium, tungsten,
uranium.

_Not in Solar Spectrum_.

Antimony, arsenic, bismuth, boron, nitrogen, cæsium, gold, indium,
mercury, phosphorus, rubidium, selenium, sulphur, thallium,
praseodymium.

With respect to these tables, Prof. Rowland adds: "The substances under
the head of 'Not in the Solar Spectrum' are often placed there because