It was wintertime on the northwest coast, and the weather was typically wet and chilly, although seldom below freezing – ideal for the propagation of bacteria that cause meat to spoil. The elk the hunters shot was often tainted before they could get it back to the fort, and was, Clark complained on 29 December 1805, "extreamly disagreeable to the Smel. as well as the taste."
Back on the plains east of the Rockies, the best recourse had been to "jerk" or "fleece" the fresh meat they didn't eat right away. That solution was problematic at Fort Clatsop. "We have yet seen no ice," the captains remarked on January 3, 1806, "and the weather so warm that we are obliged cure our meat with smoke and fire to save it. …we lost two parsels by depending on the air to preserve it, tho' it was cut in very thin slices and sufficiently exposed to the air."
It's no wonder. Bacteria multiply quickly in meat at or above 40 degrees Fahrenheit. We don't know what temperatures were like that winter, because their last thermometer had been broken early the preceding September. We do know that between 1961 and 1990 the average daily temperature ranged from a low of 18.3 degrees to a high of 43.4 degrees Fahrenheit. Bacteria also thrive in a moist habitat, and although they couldn't measure humidity in the field (the hygrometer would be invented in 1820 by Englishman John Daniell), they knew it was high. "We have not been able to keep anything dry for many days together since we arrived in this neighbourhood," Lewis wrote on January 6, "the humidity of the air has been so excessively great." In fact, today the daily average ranges between 70 and 90 percent saturation from November through March.
Salt, however, liberally massaged into meat, draws moisture to itself; the meat "perspires" and the bacteria die of thirst. The captains allotted eight of the 28 gallons the saltmakers refined for use during the rest of the winter, which should have been sufficient to preserve hundreds of pounds of meat. Yet by late February they had "three days provisions only in store and that of the most inferior dryed Elk a little tainted." It was, Lewis continued sarcastically, "a comfortable prospect for good living."
One reason could have been that the elk had moved too far south and east into the mountains, to get it to the Fort's meat house before it spoiled. Another is that they might have used a large amount of their salt supply to cure hides for clothing and moccasins. Of course, if one could scrape a hide quickly enough and air-dry it thoroughly enough – the latter an unlikely prospect at Fort Clatsop – salting wouldn't have been necessary. In any event, something worked in the long run. Sergeant Gass noted on March 13, ten days before they started for home, that they had made a total of 338 pairs of moccasins, plus a "sufficient quantitity of patch-leather" for each man. We're never told how they managed to cover the rest of their bodies, which apparently they did.
On March 20 Lewis optimistically reported "our salt will be very sufficient to last us to the Missouri where we have a stock in store." But it didn't. They were saltless again by the twentieth of June, except for two quarts that Lewis held in reserve for his anticipated trip up the Marias River, but they still had to make that strenuous trip back across the Bitterroot Mountains, and even in cold weather they would perspire heavily, and their bodies would crave salt.