Practical Density Measurement and Hydrometry

Abstract

Density determinations are very important not only for science and production but also in everyday life, since very often a product is sold by mass but the content of the package is measured by volume (or vice versa) so that the density is needed to convert the values. In production processes the density serves as a measure of mixing ratios and other properties. In science, the determination of Avogadro's constant using silicon single crystals and the potential replacement of the kilogram prototype boost density determination to an extremely low relative uncertainty of 10-7 or less.The book by S V Gupta explains in detail the foundations of any density measurement, namely the volume determination of solid artefacts in terms of the SI base unit of length and the density of water and mercury. Both the history and the actual state of science are reported. For practical density measurements, these chapters contain very useful formulae and tables. Water is treated in detail since it is most widely used as a standard not only for density determination but also to gravimetrically calibrate the capacity of volumetric glassware.Two thirds of the book are devoted to the practical density measurement of solids and liquids, mainly using classical instruments like pycnometers and hydrometers. Methods using free flotation of samples in a liquid without suspension are especially useful for small samples. Also, density determinations of powders and granular or porous samples are explained. Unfortunately, modern density meters of the oscillation type are dealt with in only a few pages.The book is clearly written and easy to understand. It contains a lot of evaluations of formulae that for practical measurements are represented in detailed tables. Methods and measurement procedures are described in detail, including also the calculation of uncertainty. Listings of the advantages and disadvantages of the different methods are very helpful.S V Gupta has written a book that will be a great help for scientists, students and practitioners. The book fills a gap since there is no modern book that describes density measurements and hydrometry in such detail.Horst Bettin