This evening I came across an assertion that a soap factory was found among the ruins of Pompeii. Naturally interested, I did a google search and came across endless assertions of this kind. Some of them asserted that the find came complete with bars of soap; some sites, indeed, felt able to state that the bars of soap were scented. But no proper references were forthcoming, which naturally made me suspicious. A very few sites had some (undocumented) statements that this was wrong, referring to the “so-called soap factory”, “so named in the 18th century”, and that the “soap turned out to be fullers earth”, but again there was no reference.
There seems to be almost nothing online about Pompeii! I don’t mean popularisations, novels, tourist visits, etc. These, indeed, are endless. But nothing scholarly; nothing reliable. Not, at least, that a simple search pursued with some industry would reveal.
In the end I was lucky, and found a book in snippet view that had done some research. It turned out to be none other than Partington’s A history of Greek fire (1960)! Which was the source for my last two posts on soap, no less!
Here’s an extract from p.308 (overparagraphed by me):
J. Sheridan Muspratt  said: “In the excavations at Pompeii a complete soap-boiling establishment was discovered, containing soap still perfect. . . . The Editor was greatly interested inspecting the factory.”
The pieces of supposed soap are in the Museo Nazionale in Naples.  A specimen of it was examined by de Luca, who reported that it blackened when heated on platinum foil, and when it was warmed with dilute hydrochloric acid “a fatty substance of the consistency of butter was set free.”
K. B. Hofmann, whilst saying that he did not question the result found by de Luca with his specimen, examined another specimen of reputed soap from Pompeii. It was insoluble in ether, alcohol and petroleum ether, had only a small part soluble in water, and effervesced with dilute hydrochloric acid, which dissolved only a small part. The residue was found by qualitative analysis to consist mainly of fuller’s earth of medium quality and it dispersed in water like this:
‘Die in der Fullonica gefundene, von mir geprüfte Masse ist also nichts als Walkerde. Was de Luca analysiert hat, weiss ich nicht—jedenfalls auch keine Seife; denn er gibt an, der unlösliche Antheil seien “thon- und kalkartige Stoffe” gewesen.’
Further, said Hofmann, soap was never found among toilet articles in Pompeii, and modern soap does not redden the hair. There was more interest taken in appearance than cleanliness; Tacitus says the Germans were dirty (sordidus) and, says Hofmann: “Wir haben uns also unsere Vorvater zwar ungewaschen, aber mit pomadierten Kopfen zu denken (We have, therefore, to think of our forefathers as unwashed but with pomaded heads),” A satisfactory history of soap has still to be written.
167. Chemistry applied to Arts and Manufactures, Glasgow, n.d. (1857-60), Division vi, 868
168. Feldhaus, Die Technik der Vorzeit, 1914, 1289.
169. Rendiconti dell’Accademia delle Scienze Fisiche e Mathematiche, Naples, 1877, xvi, 74: Sopra una materia grassa, ricavata da talune terre rinvenute a Pompeji.
170. “Ueber vermeindiche antike Seife,” in Wiener Studien. Z. f. classische Philologie, Vienna, 1882, iv, 263-70; [quote actually on p.269] Günther, in Iwan Müller, Handbuch der klassischen Altertumswissenschaft, V, i, 63, gives this title as “Graz, 1885,” which may be another publication by Hofmann.
This is rather thorough, and I suspect we may take this at face value.
An early instance of the story appears in Murray’s Handbook for travellers in Southern Italy, 1853, p.334:
Soap Factory (1786). – A small shop, which contained heaps of lime of excellent quality and other materials for soap-boiling, the vats, evaporating pans, and the moulds.
I wonder what the origin of the story is? It is certainly wide-spread, and still enjoys currency today.