We learn from this table that sound travels with different velocities through different liquids; that a salt dissolved in water augments the velocity, and that the salt which produces the greatest augmentation is chloride of calcium. The experiments also teach us that in water, as in air, the velocity augments with the temperature. At a temperature of 15° C., for example, the velocity in Seine water is 4,714 feet, at 30° it is 5,013 feet, and at 60° 5,657 feet a second. I have said that from the compressibility of a liquid, determined by proper measurements, the velocity of sound through the liquid may be deduced. Conversely, from the velocity of sound in a liquid, the compressibility of the liquid may be deduced. Wertheim compared a series of compressibilities deduced from his experiments on sound with a similar series obtained directly by M. Grassi. The agreement of both, exhibited in the following table, is a strong confirmation of the accuracy of the method pursued by Wertheim: Cubic compressibility ╭——————————————-——^————————————————╮ from Wertheim’s from the direct velocity of sound experiments of M. Grassi Sea-water 0·0000467 0·0000436 Solution of common salt 0·0000349 0·0000321 ” carbonate of soda 0·0000337 0·0000297 ” nitrate of soda 0·0000301 0·0000295 Absolute alcohol 0·0000947 0·0000991 Sulphuric ether 0·0001002 0·0001110 The greater the resistance which a liquid offers to compression, the more promptly and forcibly will it return to its original volume after it has been compressed. The less the compressibility, therefore, the greater is the elasticity, and consequently, other things being equal, the greater the velocity of sound through the liquid. We have now to examine the transmission of sound through solids. Here, as a general rule, the elasticity, as compared with the density, is greater than in liquids, and consequently the propagation of sound is more rapid. In the following table the velocity of sound through various metals, as determined by Wertheim, is recorded: VELOCITY OF SOUND THROUGH METALS Name of Metal At 20° C. At 100° C. At 200° C. Lead 4,030 3,951 ...... Gold 5,717 5,640 5,619 Silver 8,553 8,658 8,127 Copper 11,666 10,802 9,690 Platinum 8,815 8,437 8,079 Iron 16,822 17,386 15,483 Iron wire (ordinary) 16,130 16,728 ...... Cast steel 16,357 16,153 15,709 Steel wire (English) 15,470 17,201 16,394 Steel wire 16,023 16,443 ......