Crum was probably the first to recognize that some hydrogen atoms of the cellulose had been replaced by an oxide of nitrogen, and this view was supported more or less by other workers, especially Hadow, who appears to have distinctly recognized that at least three compounds were present, the most violently explosive of which constituted the main bulk of the product commonly obtained and known as guncotton.
Both these soluble hydrates are readily coagulated by traces of a salt, acid or alkali; Crum's hydrate does not combine with dye-stuffs, neither is it soluble in excess of acid, while Graham's compound readily forms lakes, and readily dissolves when coagulated in acids.
Crace-Calvert in 1871 showed that the carbon dioxide of the atmosphere was a factor; and in 1888 Crum Brown published the theory - termed the "carbonic acid theory" - that water and carbon dioxide react with iron to form ferrous carbonate and hydrogen, the ferrous carbonate being subsequently oxidized by moist oxygen to ferric hydrate and regenerating carbon dioxide, which again reacts with more iron.
Crum Brown and Fraser of Edinburgh showed that, whilst thebaine acts like strychnine, methyl and ethyl thebaine act like curara, paralysing the terminals of motor nerves.
There is a range of books by the internationally acknowledged teacher Alison Crum designed for those learning to play the viol.