This section is from the book "A Practitioner's Handbook Of Materia Medica And Therapeutics", by Thos. S. Blair. Also available from Amazon: A Practitioner's handbook of Materia Medica and Therapeutics.
Heroin, Diacetyl-Morphine. This allotropic form of morphine is an acetic ester of morphine insoluble in water but soluble in very dilute solution of acetic acid. It should not be combined with alkaline mixtures. It is advocated as a substitute for codeine, and is used in doses of 1-32 to 1-6 gr. It is a cough sedative and antispasmodic. It is a very frequent constituent of proprietary expectorants sold to the public generally. In these mixtures it is more dangerous than is morphine, since it should never be administered to children. The present author has seen heroin give rise to very sudden depression even in quite small doses.
The journals frequently report such cases, and it is developing that heroin sometimes induces a drug habit much more intractable than the morphine addiction. If employed at all, heroin should be used with the utmost of care.