Almost all of the nineteenth-century authors I have discussed so far were keen to be seen either as brewers informed by chemistry, or as chemists attuned to the brewery. If these standard self-definitions made it possible to collaborate across the divide, they also reinforced it. The separation was probably at its strongest around the mid-century, as the last of the philosophical amateurs gave way to devotees and professionals. A brewer-author such as William Black (chapter 7) might go as far as to co-produce published material with a university chemist such as Thomas Graham, but could not become a chemist in his own right: doing so would have meant the total reorientation of his life and work. The second half of the century, however, saw the growth of a brewhouse laboratory culture including researchers able to move in both spheres.