Mishna Berura Source Sheet 160:12

(1) Some materials raise the mikveh up [to the required quantity] and do not make it invalid. Some make it invalid and do not raise it up [to the required quantity]; And some neither raise it up [to the required quantity] nor make it invalid. These raise it up to the required quantity and do not make the mikveh invalid. Snow, hail, frosted dew, ice, salt, and thin mud. Rabbi Akiva said: Rabbi Ishmael once argued against me saying; snow does not raise up the mikveh [to its required quantity]. But the men of Madeba testified in his name that he had once told them: go and bring snow and with it prepare a mikveh from the outset. Rabbi Yohanan ben Nuri says: hailstones are like drawn water. How do they raise it up [to the required quantity] and not render it invalid? If the mikveh contained forty seahs less one, and a se'ah of them fell in and made up [the required quantity], they thus make up [the required quantity] but do not render it invalid.

(58) (58) If the ice is crushed (i.e. melted) etc. - But if not (melted), one does not wash the hands with a vessel. But one may immerse the hands in the snow if there is enough snow for the volume of a mikveh (40 se’ah), it is permissible in times of need, when there is no melted water. 40 se'ahs connected together, one can immerse one's hands in it. Nevertheless, it seems that it must be at least enough to cover his hands to the point they are hidden (i.e. completely covered).

In the mishna, we learned: One does not recite a blessing over wine until he adds water to it, that is the statement of Rabbi Eliezer. And the Rabbis say: One recites a blessing over it. Regarding this, the Sages taught in the Tosefta: Over wine, until he added water to it, one does not recite: Who creates fruit of the vine; rather, he recites: Who creates fruit of the tree, as it is merely fruit juice and not wine. Moreover, since it is not halakhically considered wine, one ritually washes his hands with it. Once he added water to it, however, it is considered wine, and one recites over it: Who creates fruit of the vine, and one does not ritually wash his hands with it, that is the statement of Rabbi Eliezer. The Rabbis say: In either case, whether water has been added or not, it is considered wine for all intents and purposes, and one recites over it: Who creates fruit of the vine, and one may not ritually wash his hands from it.