There is always an element of doubt in any formula as to whether you
should be using volume units or weight units. In the case of mixing sugar
and water a delightful coincidence occurs. You cannot go wrong, since
water and granulated sugar have equal weights for equal volumes.
This means that 2:1 by volume is the same as 2:1 by weight.
Note that we are talking about accuracy for practical purposes here. Small
changes occur for warm water versus cold water, packed sugar versus loose
sugar etc etc. For precision work, weights are usually better.
Donald Aitken
11710-129 Street
Edmonton Alberta Canada
T5M 0Y7