A word was coined to describe the condition of people stricken with a new kind of fever when the Swiss-born artist Angelica Kauffman (1741-1807) came to London in 1766. "The whole world", it was said, "is Angelicamad." One of the most successful women artists in history - a painter who possessed what her friend Goethe called an "unbelievable" and "massive" talent - Kauffman became the toast of Geo...