# Page:Popular Science Monthly Volume 4.djvu/304

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THE POPULAR SCIENCE MONTHLY.

are not determined by any law of Nature, but depend upon a particular collocation of matter. The same is the case with respect to the size of the earth, from which the standard of what is called the metrical system has been derived. But these astronomical and terrestrial magnitudes are far inferior in scientific importance to that most fundamental of all standards which forms the base of the molecular system. Natural causes, as we know, are at work, which tend to modify, if they do not at length destroy, all the arrangements and dimensions of the earth and the whole solar system. But though in the course of ages catastrophes have occurred, and may yet occur, in the heavens, though ancient systems may be dissolved and new systems evolved out of their ruins, the molecules out of which these systems are built—the foundation-stones of the material universe—remain unbroken and unworn.

They continue this day as they were created, perfect in number, and measure, and weight, and, from the ineffaceable characters impressed on them, we may learn that those aspirations after accuracy in measurement, truth in statement, and justice in action, which we reckon among our noblest attributes as men, are ours, because they are essential constituents of the image of Him who in the beginning created, not only the heaven and the earth, but the materials of which heaven and earth consist.

Table of Molecular Data.

 Hydrogen. Oxygen. Carbonic Oxide. Carbonic Acid. Rank I.— ${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}}$ Mass of molecule (hydrogen = 1) Velocity (of mean square), metres per second at 0° C. ${\displaystyle \scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}}$ 11,859 16465 14497 22396 Rank II.— ${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}}$ Mean path, tenth-metres.Collisions in a second (millions). ${\displaystyle \scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}}$ 96517,750 5607,646 4829,489 3799,720 Rank III.— ${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}}$ style="border-bottom:1px solid black;"|Diameter, tenth-metre.Mass, twenty-fifth grammes. ${\displaystyle \scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}}$ 5.846 7.6736 8.3644 9.31,012
 Table of Diffusion: (centimetre)2 measure. second
 Calculated. Observed. ⁠H & O 0.7086 0.7214 ${\displaystyle \scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right\}\,}}$ ⁠H & CO 0.6519 0.6422 ⁠H & CO2 0.5575 0.5558 Diffusion of matter observed by Loschmidt. ⁠O & CO 0.1807 0.1802 ⁠O & CO2 0.1427 0.1409 ⁠CO & CO2 0.1386 0.1406 H 1.2990 1.49 ${\displaystyle \scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}}$ O 0.1884 0.213 Diffusion of momentum. CO 0.1748 0.212 Graham and Meyer. CO2 0.1087 0.117 Air 0.256 ${\displaystyle \scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}}$ Copper 1.077 Diffusion of temperature observed by Stefan. Iron 0.183 ⁠Cane-sugar in water 0.00000365 ${\displaystyle \scriptstyle {\left.{\begin{matrix}\ \end{matrix}}\right\}\,}}$ Voit. ⁠Diffusion in a day 0.3114 ⁠Salt in water 0.00000116 Fick.