In the Arctic regions conversation has been maintained over water a distance of 6,766 feet. In gases the velocity of sound increases with the temperature; in air this increase is about two feet per second for each degree centigrade. The velocity of sound in oxygen gas at zero C. is 1,040 feet; in carbonic acid, 858 feet; in hydrogen, 4,164 feet.

In 1827 Colladon and Sturm determined experimentally the velocity of sound in fresh water; the experiment was made in the Lake of Geneva, and it was found to be 4,174 feet per second at a temperature of 15 degrees C. The velocity of sound in alcohol at 20 degrees C. is 4,218 feet; in ether at zero, 3,801; in sea water at 20 degrees C., 4,768.

By direct measurements, carefully made, by observing at night the interval which elapses between the flash and report of a cannon at a known distance, the velocity of sound has been about 1,090 per second at the temperature of freezing water.