The early history of Scott and Bowne’s cod liver oil

The early history of Scott and Bowne’s cod liver oil
Cod liver oil is a type of fish oil used today for general health purposes, but northern
European fishing communities used cod liver for centuries before the doctors and
chemists of 19th-century Europe began to take an interest. Its manufacture was simple:
the livers of the codfish were left for some days, then oil was taken from them. The oil
grew darker according to how long the livers were left, resulting in three grades of oil:
pale, light brown and dark brown.
Ludovicus Josephus de Jongh of the Netherlands produced the first extensive chemical
analysis of cod liver oil in 1843. His studies of the three grades of oil led him to conclude
that the light-brown oil was the most healthy. He attributed this superiority to the larger
quantities of iodine, phosphate of chalk and volatile acids found in it.
In 1846, de Jongh traveled to Norway to obtain the purest oil available. By the 1850s,
‘Dr. de Jong’s Light Brown Cod Liver Oil’ was marketed throughout Europe and
exported to the United States. Each bottle had de Jongh’s signature and stamped seal
on it – a blue codfish on a red shield – guaranteeing that the product was ‘put to the test
of chemical analysis’. Advertising emphasized de Jongh’s credentials as a doctor and
chemist, and included testimonials from other men of science and medicine.