While working on the olefines he noticed that a change takes place in the density of the vapour of amylene hydrochloride, hydrobromide, &c., as the temperature is increased, and in the gradual passage from a gas of approximately normal density to one of half-normal density he saw a powerful argument in favour of the view that abnormal vapour densities, such as are exhibited by sal-ammoniac or phosphorus pentachloride, are to be explained by dissociation.
The sulphate is still used in medicine, and the British Pharmacopeia has admitted two others, which are much more valuable - the hydrochloride and the acid hydrochloride - whilst the hydrobromide is also used.
The Hydrobromide A' acid results on boiling the A 2 acid on reduction with alkalis, or on eliminating hydroHEXAHYDRO bromic acid from i-brom-cyclo-hexane carboxylic acid-I.
Lozenges containing dextromethorphan hydrobromide should not be used in children younger than six years of age.