BRITISH ASSOCIATION FOB THE ADVANCEMENT OE SCIENCE. 53 



inorganic matter may likewise be compounds, differing from the organic radicals 

 above mentioned merely in their constituents being bound together by a closer 

 affinity. And this conjecture is confirmed by the curious numerical relations sub- 

 sisting between the atomic weights of several of these supposed elements; as, for 

 example, between chlorine, bromine and iodine : an extension of the grand general- 

 ization of Dalton, which, although it was unforeseen by the Founder of the system, 

 and therefore, like Gay-Lussac's Theory of Volume, might very possibly have been 

 repudiated by him, had it been proposed for his acceptance, will be regarded by 

 others as establishing, in a manner more conclusive than before, the soundness of 

 his antecedent deductions. What, indeed, can be a greater triumph for the theo- 

 rist, than to find that a law of nature which he has had the glory of establishing by 

 a long and painful process of induction, not only accommodates itself to all the new 

 facts which the progress of discovery has since brought to light, but is itself the 

 consequence of a still more general and comprehensive principle, which philoso- 

 phers, even at this distance of time, are still engaged in unfolding ? 



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But passing over 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 favour, which the case admits, from the har. 

 mony 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 to- 

 gether according to a particular model or type, which impresses upon the aggre- 

 gate 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 estab- 

 lished 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 accom- 

 panied 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 possessing for each other a certain degree of chemical affinity. Thus, 

 when we unite hydrogen with oxygen, we substitute an atom of the latter for one 

 of the former, previously combined with the same element. 



To the microscope we owe all that is as yet known with respect to the reproduc- 

 tive process in cryptogamous plants, which are now shown to possess a structure 

 analogous to that of flowering ones in respect to their organs of reproduction ; 

 not, indeed, as Hedwig supposed, that parts corresponding to stamens and pistils 

 in appearance and structure can be discovered in them, but that as the primary 

 distinction of sexes seems to run throughout the Vegetable Kingdom, new parts 

 are superadded to a structure common to all as we ascend in the scale of creation, 

 until from the simple cell, which, in consequence of some differences of structure, 

 to our eyes inappreciable, appears to exercise in one case the function of the male, 

 in another of the female, as is found the case in certain of the Confervas, we arrive 



