PRESERVATION OF THE MAMMOTH CAVE MUMMY

By Ned J. Burns,
Chief, Museum Division,
Washington

The desiccated body of an Indian was discovered in Mammoth Cave National Park, Kentucky, about four years ago on a ledge under a large rock which, in falling, had caused his death in pre-Columbian times. This find aroused considerable scientific, as well as popular interest, and shortly thereafter the two-ton rock was raised to afford a better opportunity to examine the body. Since it was not considered feasible to leave this unusual specimen on the ledge, the body was removed to the cave floor immediately below and placed in a glass display case to protect it from handling by visitors.

About two months after the change was made it was noted that mold was growing rapidly over the body, which would soon deteriorate unless prompt steps were taken to prevent further inroads. The Museum Division was called in at this point and we made an investigation to determine the cause and supply a remedy. It was apparent at once that the immediate cause of trouble was a noticeable rise in temperature due to the presence of tubular lamps installed inside the case as part of the original equipment of the dry goods display, as well as the fact that the case was far from air-tight. The rise in temperature also increased the moisture content of the body by the process of bringing in new moisture-laden air every time the lights were turned off and the air contracted within the case. These increases in temperature and moisture content had evidently upset the conditions existing in the centuries during which the body remained unchanged, and had stimulated mold growth.

We made an effort to discover the reason why this body had been preserved, when it is well known that animal and vegetable matter left in the cave for even short periods is soon attacked by mold in the prevailing humidity of 86 per cent and almost constant year round temperature of 54 degrees Fahrenheit. Wood used for steps and railings becomes unsafe within a year or two unless treated with creosote. We noted that bark sandals and other material contemporary with this mummy have been dug out of the cave sand in a good state of preservation, due to the presence of sodium nitrate or saltpeter, which is abundant and has been leached from the cave sands in paying quantities, notably for manufacturing gunpowder during the War of 1812. A chemical analysis of the body tissues of the mummy and the sand bed on which it had rested disclosed the presence of sodium nitrate, selenium, and a slight trace of arsenic. It is also noteworthy that the mummy's condition was peculiar in that instead of being dry and hard, as desiccated bodies found in very dry caves usually are, the flesh was slightly pliable like wet leather. A study of the evidence led me to believe that preservation was effected in the following manner.

After death the body began to decay and the fluids were absorbed by the sand bed into which it was pressed. This excess moisture dissolved out the sodium nitrate present and when the moisture content of the sand bed exceeded that of the body the fluids were reabsorbed, bringing up into the tissues this excellent preservative. This process continued until enough sodium nitrate had been infiltrated to arrest further decay; and under the cave conditions, which never changed to any perceptible degree, the body had remained preserved until discovered. Obviously it was impossible to restore these delicately balanced conditions; so after a careful study I decided upon the following method of preservation, which was carried out.

First the noticeable mold growth was cleaned away with a soft brush and later other objectionable spots were removed with acetone, ammonia, saponin, and other solvents as individual local areas indicated. A large wooden box with an air-tight cover was built, having a wire mesh shelf set up so that the mummy could be reached by a stream of warm dry air supplied by a blower improvised from electric fixtures and a vacuum with blower attachment. Ten pounds of dehydrated calcium chloride was placed in the box and removed several times during treatment as its moisture content rose sufficiently to warrant replacement. Careful watch was kept to be sure no damage resulted in the body from the drying process, and none was noted. The body was then carefully impregnated with thymol dissolved in alcohol, and after all alcohol was evaporated the specimen was installed in a specially constructed, waterproof and rust proof case fitted with gaskets to insure a perfectly tight fit.

An unusual feature of this case is the specially designed chemical tray under the bottom, fitted with a trap door, which automatically closes a small opening into the case proper before it can be withdrawn. When the tray is placed in position it releases a spring which opens the valve into the case, permitting contact with the inside air. A supply of thymol and calcium chloride is kept in this tray both to poison and dehydrate the air surrounding the mummy. Since mold cannot grow without moisture and a good fungicide is also present --- a double safeguard against a recurrence of trouble --- it is possible to exhibit this interesting specimen in the cave as near as practicable to the site where it was originally found, in spite of the adverse conditions of high humidity which existed there.

Periodic inspections during the past three years have not revealed any noticeable change in the condition of the body. It is therefore safe to assume no further difficulty will be encountered so long as the case remains intact and the chemicals are periodically renewed. (From The Museum News, Vol. XVII, No. 9, November 1, p.8)