166 Mr. R. Brown on the Existence of active Molecules 



the surface of the bodies regarded as the stamina of Equi- 

 setum,— and lastly in bruised portions of other parts of the 

 same plants, were in reality the supposed constituent or ele- 

 mentary molecules of organic bodies, first so considered by 

 BufFon and Needham, then by Wrisberg with greater pre- 

 cision, soon after and still more particularly by Muller, and, 

 very recently by Dr. Milne Edwards, who has revived the 

 doctrine and supported it with much interesting detail. I 

 now therefore expected to find these molecules in all or- 

 ganic bodies: and accordingly on examining the various 

 animal and vegetable tissues, whether living or dead, they 

 were always found to exist; and merely by bruising these 

 substances in water, I never failed to disengage the molecules 

 in sufficient numbers to ascertain their apparent identity in 

 size, form, and motion, with the smaller particles of the 

 grains of pollen. 



I examined also various products of organic bodies, parti- 

 cularly the gum-resins, and substances of vegetable origin, 

 extending my inquiry even to pit-coal ; and in all these bo- 

 dies Molecules were found in abundance. I remark here also, 

 partly as a caution to those who may hereafter engage in the 

 same inquiry, that the dust or soot deposited on all bodies in 

 such quantity, especially in London, is entirely composed of 

 these molecules. 



One of the substances examined, was a specimen of fossil 

 wood, found in Wiltshire oolite, in a state to burn with 

 flame; and as I found these molecules abundantly, and in 

 motion in this specimen, I supposed that their existence, 

 though in smaller quantity, might be ascertained in mineralized 

 vegetable remains. With this view a minute portion of silicified 

 wood, which exhibited the structure of Coniferce, was bruised, 

 and spherical particles, or molecules in all respects like those 

 so frequently mentioned, were readily obtained from it; in 

 such quantity, however, that the whole substance of the petri- 

 faction 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 ascer- 

 tain to what extent the molecules existed in mineral bodies, 

 became the next object of inquiry. The first substance ex- 

 amined 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 

 motion with those which I had already seen. 



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



minerals 



