Chemist who gave us soap and marge

In the context of the current debate about retirement age, it is intriguing to take a look at the life of a 19th century French chemist who retired from his job in chemical manufacturing only as he neared the age of 100 and who remained active in academic life even after his 100th birthday.

Michel Eugène Chevreul is remembered today mainly for his pioneering work with fatty acids, which led to their use in the manufacture of soap, margarine and candles.

His 1823 treatise on animal fats became the basis for the modern knowledge of fats. Born in 1786 in Angers, he was educated in his native town before going at the age of 17 to Paris, where he worked for the chemical manufacturer, Vauquelin. By the age of 20 he was contributing to the scientific literature, and at 26 had attained the rank of professor at the Lycée Charlemagne.

According to an article by Mayer and Hanson in the Journal of Nutrition in 1960, one of Chevreul’s early papers dealt with the manufacture of soap from spermaceti, the wax-like substance obtained from the head of the sperm whale. In 1814, he showed that lard contained essentially two main fats, one solid at room temperature which he called “stearine” and the second liquid, which he called “elaine”. From these two fats he isolated the fatty acids stearic acid and elaidic acid (an isomer of oleic acid).

Together with Gay Lussac, Chevreul later took out a patent for the manufacture of the stearic acid candle, a process still in use today, which at that time replaced candles made of tallow, bayberry wax or other fats.

In 1813, Chevreul went on to make soap from lard and potash, from which he crystallised potassium stearate, a substance he called “margaric acid” from the Greek for “mother of pearl” (margaron) because of its milky drop appearance in aqueous solution. However, it was not until 1869 that another French chemist, Mége Mouriés, won a competition for a product he called margarine, after its primary ingredient, “margaric acid”.

In 1824, Chevreul was appointed director of the Gobelins dye works, a post he gained because of his reputation as a chemist and his interest in the chemical structure of dyes. He then developed an interest in the optics of colours and made the observation that “every colour when placed beside another colour is changed, appearing different from what it really is and moreover equally modified the colour with which it is in proximity”.

Chevreul applied this rule to number of colour combinations and in later publications described its application to painting, tapestries, mosaics, coloured glazing, calico printing, map colouring and so on.

Chevreul remained director of the dye works until the age of 97. Even then he continued as a professor. Moreover, at the age of 101, he completely revised his organic chemistry course to do justice to this enormously expanded field.

Chevreul’s 100th birthday in 1886 was celebrated with distinctions, honorary degrees and messages from every corner of the world, including one from Queen Victoria. But the chemist apparently disclaimed any particular merit save that of being the “the oldest among students in France”. He died in Paris two years and seven months later at the age of 102.