Geriaviator (#10326), MPN11 (#10327), JW411 (#10328), Fantom Zorbin (#10329), Chugalug (#10330),and ricardian (10331),
You drink a lot of plain water, what sweats out is salt (4 [?] % - a distant memory of our acquatic origins). That has to be replaced to maintain health.
So the salt tablets, in hot weather they were put out in the Messes in bowls, you were supposed to suck one a day, but I can't remember any checks on you. They were off-white, about the size of an "Ovaltine" tablet, I think.
In India, we had small yellow "Mepacrine" tablets as an anti-malaria prophylactic. One per day, no checks (turned you yellow, too !)
JW411, don't remember any laxative effect. But in India then anything you ate or drank was apt to send you off with the "Runs" !
ricardian, I still have my "Spectacles Anti-Glare" in the blue case. Seems I unaccountably failed to hand them in. Naughty, naughty !
Danny.