Halocho #36 - Snow on Shabbos

On Shabbos one may not crush snow or hail - causing them to dissolve, but one may put snow or hail into liquids where they will dissolve by themselves. On Shabbos one may not shake a black garment to remove the snow or dust from it. Source: Kitzur Sulchan Aruch 80: 14, 39. The 39 categories of activity prohibited on shabbat