Natural Philosophy for Beginners Author:Isaac Todhunter Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: III. VELOCITY OF SOUND IN OTHER MEDIA, 29. Sound may be transmitted through the various gases. The theoretical value of the velocity would be similar to that ... more »of Art. 12; and it would require a similar correction to that of Art. 13, on account of the heat developed and absorbed. It is not easy to determine the velocity by experiment in a direct manner, as we cannot procure a column of any gas of sufficient length and purity; but theory points out a connexion between the velocity of sound and the pitch of the note produced by an organ pipe, and thus by filling an organ pipe with the gas to be examined the velocity of sound in the gas is indirectly determined. It is found that at the temperature of the freezing point of water the velocity is 1040 feet per second iu oxygen, and 4164 feet per second in hydrogen. 30. Hydrogen, the lightest of the gases, is somewhat peculiar in relation to sound. The velocity of sound in this gas, as we have just stated, is about four times as great as in air. But the most remarkable circumstance is the power which hydrogen seems to possess of deadening sound and almost stifling it. The sound of a bell in a receiver charged with hydrogen is said to be scarcely more audible than that of the bell in an exhausted receiver. 31. The transmission of sound through vapours presents some points of interest arising from the fact that a vapour readily condenses, at least partially, into a liquid, when there is an increase of pressure, such as according to theory must occur in the course of the transmission of sound. But on the other hand if the temperature is sufficiently raised the condensation into a liquid is prevented; and it appears from experiment that there is such a rise of temperature. Thus we obtain some indirect confirmation of the truth of the ...« less