Dry out black bread until it browns but do not let it burn. Break up the bread, pour one glass of the crumbs into a stoneware bowl, add 3 glasses of boiling water from the samovar, and cover with a plate for 15 minutes. Immediately strain through a fine sieve, measure and, if there is less than 3 glasses, add more boiling water, pouring it over the bread in the sieve. Add ½ lb sugar and 5 isinglass or 5 sheets gelatin and bring to a boil to dissolve the gelatin. Pour into a soup tureen and let it cool. When it begins to set, beat with a whisk over ice until it foams, transfer to a mold, and chill, etc.