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Jerboy
03-11-2002, 12:58 AM
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 3.98C 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.

454Casull
03-11-2002, 11:29 AM
Maybe the editor decided to have some fun. And this belongs in HT? :)

Demon-Xanth
03-11-2002, 01:08 PM
They did thier calculations on an early Pentium

ElFenix
03-11-2002, 06:05 PM
ummm... didn't the french define a mL = cm^3? merck can't just redefine it.


yet another indication that companies are becoming too powerful.

highwire
03-11-2002, 07:47 PM
Yes, this difference between the milliliter and the cubic centimeter was well known among the well trained.

An old chem. textbook has the definition as 1 milliliter = 1.000027 cc.
I looked at a few pages at link (http://scienceworld.wolfram.com/physics/cgs.html) to try to sort it out. Not much help with the old definitions.
I think, with SI/MKS and the redefinition of the meter, etc., they are now the same. However, it is still murky to me just what the EXACT weight/density of water is under the SI.

Edit: Ok, the answer is in your orig post. water weighs a little less than 1 gram/cc. The ml had been defined as the volume of 1 gram of water - a small amount larger than 1 cc.

Jerboy
03-11-2002, 09:09 PM
<< Yes, this difference between the milliliter and the cubic centimeter was well known among the well trained.

An old chem. textbook has the definition as 1 milliliter = 1.000027 cc.
I looked at a few pages at link (http://scienceworld.wolfram.com/physics/cgs.html) to try to sort it out. Not much help with the old definitions.
I think, with SI/MKS and the redefinition of the meter, etc., they are now the same. However, it is still murky to me just what the EXACT weight/density of water is under the SI.

Edit: Ok, the answer is in your orig post. water weighs a little less than 1 gram/cc. The ml had been defined as the volume of 1 gram of water - a small amount larger than 1 cc. >>




Thanks highwire. Headsup from someone was exactly what I needed. Now can somebody come up with a few more credible sites? Didn't find anything on National Institutes of Standards and Technology homepage.

highwire
03-11-2002, 10:12 PM
Here is another link - the history of the liter: Text (http://www.sizes.com/units/liter.htm)

Interesting site for the history of other units as well. One who was involved with making the meter met the guillotine. Envy reigned then in France as a national policy of madness.

exp
03-12-2002, 12:27 PM
Interesting...