Noted Doug's reply re: water purification, antiseptic, antifungal. SAS book also notes will mark snow for signalling and can be reacted with sugar (e.g. from combat ration) by crushing together small portions of both on a hard surface and will ignite. Also can be ignited by dripping a drop or two of brake fluid or antifreeze onto a half teaspoon of crystals.<br>Hope this is of some assistance - and that I'm not telling you something you've heard already!