Herapath was born in Bristol, where father was a maltster in St. Philip's parish, and after his death succeeded to the business.
He was one of the founders of the Chemical Society of London, of which he was a fellow, and also of the Bristol Medical School, of which he became professor of chemistry and toxicology on its opening in 1828.
[1] On 13 April 1835, at the trial of a woman named Burdock for poisoning by arsenic her lodger, Mrs. Clara Ann Smith, at Bristol, Herapath was expert witness for the prosecution, and made a reputation by his analysis.
In the case of William Palmer of Rugeley in 1856, when he was a witness for the defence, he was severely handled by Alexander Cockburn, who denounced him as a "thoroughgoing partisan".
On the passing of the Municipal Reform Act, he became a member of the town council, and then a justice of the peace.