Essays biographical and chemical

I. Historical essays: The early days of chemistry.--The great London chemists: I. Boyle and Cavendish. II. Davy and Graham.--Joseph Black: his life and work.--Lord Kelvin.--Pierre Eugène Marcellin Berthelot. II. Chemical essays: How discoveries are made.--The Becquerel rays.--What is an element?--On the periodic arrangement of the elements.--Radium and its products.--What is electricity?--The aurora borealis