1818.] the Commencement of the Year 1817. Part I. 9 



would appear, from the experiments of Mr. Faraday, that the 

 rapidity of the flow of gases in such circumstances diminishes 

 as their specific gravity augments. Into a copper vessel, capable 

 of holding 100 cubic inches, he compressed four atmospheres of 

 the following gases, and then measured the time that elapsed 

 during their issuing out through a thermometer tube, 20 inches 

 in length, till the density was diminished to an atmosphere and 

 a quarter. The time was measured by a seconds pendulum. 

 The following table shows the number of seconds that elapsed 

 during the flow of each gas : 



Carbonic acid gas 156*5" 



Olefiant gas 135*5 



Carbonic oxide .... 133*0 



Common air , ... 128*0 



Coal gas 100-0 



Hydrogen 57*0 



A wheel, carrying on its circumference a number of small 

 vanes, was made to revolve with a given force in different gases. 

 The time that the motion continued in the different gases is 

 shown by the following table : 



Carbonic acid gas 6" 



Common air 8 



Coal gas 10 



Hydrogen 17 



When gases are subjected to very small pressures, there does 

 not appear to be any connexion between their specific gravities 

 and the time which they take in flowing out through small tubes. 

 Olefiant gas passes with as much facility as hydrogen, and 

 twice as rapidly as carbonic oxide and common air. Carbonic 

 acid escapes much more rapidly than gases inferior to it in 

 density. Analogous results are obtained even under consider- 

 able pressures when the caliber of the tube is sufficiently dimi- 

 nished. The time of flowing out in such cases presents 

 anomalies, probably owing to some loss of force in the tube ; 

 and it offers to mathematicians an interesting object of research. 

 — (Royal Institution Journal, iii. 354.) 



2. Specijic Gravity of the Gases. — Professor Meinecke, of 

 Halle, has published a table of the specific gravity of gases, 

 drawn from a comparison of the various experiments hitherto 

 made upon the subject; and, therefore, similar to the tables of 

 Gay-Lussac and my own, formerly laid before the readers of the 

 Annals. As this is a subject of first rate importance, and can 

 only be brought to perfection by slow degrees, every additional 

 fact relating to it deserves attention. 1 shall on that account 

 transcribe Meinecke's table here. This document being almost 

 entirely derived from other sources, which must be familiar to 



