Michel-Eugène Chevreul (1786-1889)

Chemical inquiries into the nature of several fatty substances, and particularly on their combinations with the alkalis. Of a new substance, called margarine, obtained from the soap made from the fat of pork and potash

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When we immerse soap made of pork grease and potash in a large quantity of water, one part is dissolved, while another is precipitated in the form of several brilliant pellets, which I shall call mother of pearl substance.

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The fatty substance, separated from the salifiable bases, was dissolved in boiling alcohol: on cooling, it was obtained crystallized and very pure, and in this state it was examined. As it has not been hitherto described, it ought to be distinguished from other substances by a peculiar name: consequently I purpose to call it margarine, from the Greek word signifying pearl, because one of its characters is to have the appearance of mother of pearl, which it communicates to several of the combinations which it forms with the salifiable bases.

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I now come to speak of one of the most remarkable combinations of margarine, being that which it forms with potash. It truly characterizes this substance, and leads me to examine some points of the chemical doctrines respecting acidity.

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... turnsole appears to be adopted by all chemists to detect acidity. ... we shall be compelled to rank margarine among the [acids]; since it reddens turnsole, takes up potash from the carbonic acid, and since its combinations with this base have the greatest analogy with the salts. If it be objected that its composition removes it too far from the series of the acids, we may cite a single example, that of sulphuretted hydrogen, which evidently possesses the characters of acidity, as M. Berthollet has proved. All the chemists, in regarding this body as an acid, have, I believe, established that in the chemical system the analogy of properties has been consulted in preference to that of composition.