"On exposure to air they (the mummies) become covered with efflorescence of sulphate of soda, and also readily absorb moisture from the atmosphere."
It appears, also, that after the period of preparation (thirty, forty, or seventy days, as fixed by various authors), the corpse was relieved, in the first-class ones, of all the old saline, nitrous, or resinous products, and re-filled with costly resins, aromatic spices, and bitumen; which, says Monsieur Rouyer -
"Having styptic, absorbent, and balsamic qualities, would produce a kind of tanning operation on the body, which would also, no doubt, be heightened by the washing with palm wine."
He here broaches the ingenious and highly probable theory, that the corpse, during its mummification, was placed in stoves of a certain temperature, where the heat gradually and closely united the various preservative agents before mentioned. They were then swathed in linen bandages of great length, and enclosed in beautifully painted and gilded cartonages; the faces were heavily gilded and the eyes imitated in enamel; they were then inclosed in three or four cases, also richly gilded and painted, and finally "mounted" in a sarcophagus.
Common people appear in some cases to have been merely salted and plunged in liquid pitch, others were simply salted and dried. Mummies prepared by these methods freely attract moisture — are ill preserved, and, therefore, as a matter of course, fall to pieces easily on contact with external air.
In summing up the process of embalming, as described by the authors just quoted, we find a few problems of more or less difficulty, and which none of them appear inclined to solve; and I do not wonder at this, as the attempt, in my own case, in one or two instances, has involved days of study and references to dozens of medical and other works with but a meagre result. However, to take them seriatim, we can assume, I think, with some show of evidence, that the Ethiopian stone, mentioned as being used to make the first incision in the corpse, might have been a piece of obsidian or basalt, but most probably was merely an ordinary sharp flint of a dark colour.
The first chemical used in embalming is the hardest nut of all to crack, and on which I have most exercised my intellectual teeth — and that is natron. Now, what is natron? [Footnote: Natrium is the old Latin term for the metal or base we now call sodium. The old names for some of its salts were: Natron Carbonicum--or Bicarbonate of Soda; Natron Vitriolatum — or Sulphate of Soda; discovered or re-discovered about 1670. Nitrum =Carbonate of soda.] Ordinary dictionaries and authors tell us, as a matter of course — carbonate of soda. In support of this theory M. Rouyer writes:
"The natron would be used just as it was got from many of the lakes of Egypt, where it is found abundantly in the form of carbonate of soda."
Pereira, in "Materia Medica," though intimating that natron is not to be confounded with nitre, says, in speaking of carbonate of soda:
"This salt was probably known to the ancients under the term of Nitron." (Nitron)