Mr Brown's Microscopical Observations. 341 



molecules abundantly, and in motion in this specimen, I supposed that 

 their existence, though in smaller quantity, might be ascertained in mi- 

 neralized vegetable remains. With this view a minute portion of silicified 

 wood, which exhibited the structure of coniferae, was bruised, and spheri- 

 cal particles, or molecules in all respects like those so frequently mention- 

 ed, were readily obtained from it ; in such quantity, however, that the 

 whole substance of the petrifaction seemed to be formed of them. But 

 hence I inferred that these molecules were not limited to organic bodies, 

 nor even to their products. 



To establish the correctness of the inference, and to ascertain to what 

 extent the molecules existed in mineral bodies, became the next object of 

 inquiry. The first substance examined was a minute fragment of window - 

 glass, from which, when merely bruised on the stage of the microscope, I 

 readily and copiously obtained molecules agreeing in size, form, and mo- 

 tion with those which I had already seen. 



I then proceeded to examine, and with similar results, such minerals as 

 I either had at hand or could readily obtain, including several of the 

 simple earths and metals, with many of their combinations. 



Rocks of all ages, including those in which organic remains have never 

 been found, yielded the molecules in abundance. Their existence was as- 

 certained in each of the constituent minerals of granite, a fragment of the 

 sphinx being one of the specimens examined. 



To mention all the mineral substances in which I have found these mo- 

 lecules would be tedious ; and I shall confine myself in this summary to 

 an enumeration of a few of the most remarkable. These were both of 

 aqueous and igneous origin, as travertine, stalactites, lava, obsidian, pumice, 

 volcanic ashes, and meteorites from various localities *. Of metals I may 

 mention manganese, nickel, plumbago, bismuth, antimony, and arsenic. 

 In a word, in every mineral which I could reduce to a powder, sufficient- 

 ly fine to be temporarily suspended in water, I found these molecules 

 more or less copiously ; and in some cases, more particularly in siliceous 

 crystals, the whole body submitted to examination appeared to be com- 

 posed of them. 



In many of the substances examined, especially those of a fibrous struc- 

 ture, as asbestus, actinolite, tremolite, zeolite, and even steatite, along with 

 the spherical molecules, other corpuscles were found, like short fibres 

 somewhat moniliform, whose transverse diameter appeared not to ex- 

 ceed that of the molecule, of which they seemed to be primary combina- 

 tions. These fibrils, when of such length as to be probably composed of 

 not more than four or five molecules, and still more evidently when form- 

 ed of two or three only, were generally in motion, at least as vivid as that 

 of the simple molecule itself; and which, from the fibril often changing 

 its position in the fluid, and from its occasional bending, might be said to 

 be somewhat vermicular. 



In other bodies which did not exhibit these fibrils, oval particles of a 

 size about equal to two molecules, and which were also conjectured to be 



* I have since found the molecules in the sand-tubes, formed by lightning, from 

 Drig in Cumberland. 



