In practice this usually occurs; for example, on further bromination, a-bromonaphthalene yields a mixture of the (i.4) and (1.5) dibromonaphthalenes; and when nitronaphthalene is either brominated, or nitrated or sulphonated, the action is practically confined to the second ring.
When heated to 250° C. with red phosphorus and hydriodic acid it gives a hydride It is nitrated by nitric acid and sulphonated by sulphuric acid.
At the time these products were thought to be related to the nitrated starch obtained a little previously by Henri Braconnot and called xyloidin; they are only related in so far as they are nitrates.
Other products were soluble in the ether-alcohol mixture: they were less highly nitrated, and constituted the so-called collodion guncotton.
In the recent methods the cotton remains in contact with the acids for two to four hours at the ordinary air temperature (15° C.), in which time it is almost fully nitrated, the main portion, say 90%, having a composition represented by the formula e C6H702(N03)3, the remainder consisting of lower nitrated products, some oxidation products and traces of unchanged cellulose and cellulose sulphates.