The Concepts of Volume Measurement

It does not seem that it should be difficult to calculate the volume of any given container. First you establish a unit of volume, then you base everything on that unit. Despite the apparent simplicity of such a process, two widely divergent approaches to calculating a volume unit have developed. 

One approach established that a liter was the volume of space occupied by the mass of one kilogram of distilled water (at 4°C and 30 inches of mercury). The other approach required a given length measurement to be defined (one decimeter), and then it defined the cube of that measurement as the volume measurement (one liter). 

The original idea of the metric system was that either approach would provide the same unit of metric volume. Unfortunately, it did not work because of the subtle differences in density caused by subtle differences in temperature. Thus, the kilogram-based milliliter equaled 1.000,027 cubic centimeters. Because of the discrepancy, the International System for Weights and Measures had to make a choice between which approach would be accepted to obtain volume measurements, and the nod was eventually given to the cubic length technique. The use of liters and milliliters in volumetric ware is therefore misleading because the unit of volume measurement should be cubic meters (cubic centimeters are used as a convenience for smaller containers). The International System of Units (SI) and the ASTM accept the use of liters and milliliters in their reports, provided that the precision of the material does not warrant cubic centimeters. Because the actual difference in one cubic centimeter is less than 3 parts in 100,000, for most work it is safe to assume that 1 cm3 is equal to 1 mL. 

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