To my knowledge brich sap does not keep and needs to be processed, syrup or beer, within a few days of coming out of the tree. Could it be frozen? IDK but i wouldn't pay for the shipping on 5 gallon block of ice.
For anyone interested i did finally find some http://www.faeriesfinest.com/E183.html?gclid=CLSl87Xw47UCFcdDMgodx2AAyA
The pic in this is not correct, It IS the clear kind.
Still experimenting, but 10 drops birch beer extract, 4 tsp sugar, 1 drop cinnamon oil mixed in 20oz seems to make a good soda... so far...