Page:Popular Science Monthly Volume 4.djvu/304

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.—	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mass of molecule (hydrogen = 1) Velocity (of mean square), metres per second at 0° C.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	1 1,859	16 465	14 497	22 396
Rank II.—	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	Mean path, tenth-metres. Collisions in a second (millions).	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	965 17,750	560 7,646	482 9,489	379 9,720
Rank III.—	$\scriptstyle {\left\{{\begin{matrix}\ \\\ \end{matrix}}\right.}$	style="border-bottom:1px solid black;"|Diameter, tenth-metre. Mass, twenty-fifth grammes.	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$	5.8 46	7.6 736	8.3 644	9.3 1,012

 

Table of Diffusion:	(centimetre)2	measure.
	second

 

	Calculated.	Observed.
H & O	0.7086	0.7214	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \\\ \\\ \ \end{matrix}}\right\}\,}$
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	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$
O	0.1884	0.213		Diffusion of momentum.
CO	0.1748	0.212		Graham and Meyer.
CO2	0.1087	0.117
Air		0.256	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$
Copper		1.077		Diffusion of temperature observed by Stefan.
Iron		0.183
Cane-sugar in water 0.00000365			$\scriptstyle {\left.{\begin{matrix}\ \end{matrix}}\right\}\,}$	Voit.
Diffusion in a day 0.3114
Salt in water 0.00000116				Fick.