@Jim Carroll: I suspect your story mixes 3 Franklin expeditions! 1819 he was sent to Canada to go overland from Hudsons Bay to the Polar sea and map the coastline. Such an expedition requires setting out food caches. However, on the return journey they missed some of the caches with the result that 10 crew members died. 1825-1827 the admiralty sent him back to the area to carry on mapping where he'd left off in 1819. Presumably this time they found the caches they'd missed in 1819. Since, with 10 exceptions, all returned safely, it's the events of these expeditions which were remembered, mixed together and passed on.

@Steve Gardham: By all accounts now it wasn't so much the solder on the food tins as the concentrated supply of lead from the steam boilers on board that caused the poisoning. The sailors on Beechey Island had high lead levels but they also had diseases like TB. A consequence of the two mapping expeditions was that, when the ships were abandoned, Crozier and Fitzjames knew where they were heading for and, since they wouldn't be coming back, there was no sense in food caches.