22 ANNUAL OF SCIENTIFIC DISCOVERY. 



distance of time, are still engaged in unfolding ? It is also curious to reflect, 

 that whilst the bold speculations of Demc-oritus have been realized by the 

 Manchester philosopher, the reveries of the alchemists derive something like 

 solid support from the minute investigations of his successors. "We may 

 remark, indeed, as not a little remarkable, how frequently the discoveries of 

 modern days have served to redeem the fancies of mediaeval times from the 

 charge of absurdity. If the direction of a bit of steel suspended near the earth 

 can, as Colonel Sabine has proved, be influenced by the position of a body like 

 the moon, situated at a distance from it of more than 200,000 miles, who shall 

 say that there was anything preposterously extravagant in the conception, 

 however little support it may derive from experience, in the influence ascribed 

 to the stars over 'the destinies of men by the astrologers of olden time ? And 

 when we observe a series of bodies, exhibiting, as it would seem, a gradation 

 of properties, and, although as yet undecompounded, possessing a common 

 numerical relation one to the other, who will deny the probability that they 

 are composed of the same constituents, however little approach we may have 

 as yet made towards the art of resolving them into their elements, or of form- 

 ing them anew ? Organic chemistry has also considerably modified our views 

 with respect to chemical affinity. According to one view, indeed, which has 

 been supported of late with considerable talent and ingenuity, the law of 

 elective attraction, to which we have been in the habit of referring all the 

 changes that are brought about by chemical means, is a mere figment of the 

 imagination ; and decomposition may be accounted for, without the interfer- 

 ence of any such force, by regarding it simply as the result of that constant 

 interchange which is supposed to be going on between the particles of 

 matter the atoms even of a solid body being, according to this hypothesis, 

 in a state of incessant motion. But passing over these and other speculations 

 which have not as yet received the general assent of chemists, let me advert 

 to others of an older date, possessing, as I conceive, the strongest internal 

 evidence in their favor which the case admits, from the harmony they tend to 

 introduce into the chaos of facts which the late discoveries in organic 

 chemistry have brought to light. Amongst these, one of the most generally 

 received, and at the same time one of the most universal application, is that 

 which represents the several combinations resulting from organic forces, as 

 being put together according to a particular model or type, which impresses 

 upon the aggregate formed certain common properties, and also causes it to 

 undergo change most readily through the substitution of some other element 

 in the place of one of those which already enters into its constitution. And 

 this principle, having been established with regard to one class of bodies, has 

 since been extended to the rest ; for it now begins to be maintained, that in 

 every case of chemical decomposition a new element is introduced in the place 

 of one of those which constituted a part of the original compound, so that the 

 addition of a fresh ingredient is necessarily accompanied by the elimination 

 of an old one. The same doctrine, too, has even been extended to the case 

 of combination with a body regarded as elementary, for here also the particles 

 are considered as being in a state of binary combination one with the other, 

 owing perhaps to their existing in opposite electrical conditions, and therefore 



