Importance of density measurements
Architects and engineers refer to tables giving the densities of various building materials when engaged in the design of bridges, ftyovers, and other structur From the plans drawn up, they can calculate the volume of any part of the structure
which, multiplied by the density of the material, gives the mass and hence the weigh Such information is essential for calculating the strength required in foundatio and supporting pillars.
Chemists often make a density determination as a test of the purity of a subs tan One such test made many years ago led to the discovery of a new gas which has in become very useful industrially. It had been known for a long time that nitro g obtained from air was slightly denser than that obtained from other sources. Otherwise the two kinds of nitrogen appeared to be identical. The difference in density led Lord Rayleigh and Sir William Ramsay to suspect that atmospheric nitrogen contained small quantities of a heavier gas. Following this clue they began a series of experiments and eventually succeeded in isolating a new gas to which the name of argon was given.
Argon at low pressure is used in gas-filled electric lamps. It enables the filament to be run at a higher temperature than in a vacuum, and so to give more light per unit of electric energy.