William Willis introduced in 1879 a photographic paper that used platinum instead of silver salts. This platinotype paper had several advantages over the papers then in use. The image was permanent. It produced an extremely beautiful tonal range; as anyone will confirm who saw the recent Frederick Evans exhibition at the Victoria and Albert Museum. His great pictures of cathedral interiors are living examples to the beauty of the platinotype process. Cost killed the platinotype. Platinum metal increased in price by nearly three times between 1879 and 1891, and rose still higher in later years. By World War I the paper, sadly, was obsolete.