In a regular context, we assume that ml and cc are equilvalent. They're actually not. I read this somewhere on the net or in a book. The particular source said that they're different by very minute quantity. This popped into my mind today, because a data on water I was reading indicates the difference. It states that density of water at 3.98°C is 1.000000g/ml or 0.999972g/cc. If you don't believe me, look in Merck Index 12th edition, chemical # 10175, water. I know I read it once already, but I'd like the exactly number in the book again. I didn't find anything on Google. Just about everything I found there assumed ml=cc.