EVOLUTION OF THE CHEMICAL ELEMENTS. 529 



which they give rise, either in their natural condition, or, as is usually 

 the case, under certain artificial conditions to which the ingenuity of 

 man has learned to subject them. As these aggregates are the lowest 

 which can be perceived, they have been denominated elements, and 

 are by some supposed to constitute the ultimate units of matter. But, 

 independently of certain direct evidence against this view, it is far 

 more consistent with what is now known of matter, and with the laws 

 of thought, to regard them as the first or lowest stages of aggregation 

 whose activities are capable of appealing, either directly or indirectly, 

 to our senses. It is really no more probable that the so-called elements 

 are tlie lowest subdivisions of matter than that the remotest stars 

 visible are actually at the confines of the universe. 



That these elements are capable of manifesting themselves to sense 

 is the sole reason of our recognizing their existence ; and the history of 

 their discovery, by which their number has been so greatly increased, 

 shows that their modes of manifestation are often so subtile as to 

 escape all but the most thorough methods of detection. Many of 

 these elements now universally recognized remained for a long time 

 wholly unsuspected, and these then belonged to the great class of un- 

 known aggregates. This interesting chapter in the history of science 

 should suffice to teach us that below the known of to-day there lies a 

 wide belt of the knowable unknown, and that other and still lower 

 orders of aggregates will doubtless yet be induced to reveal their 

 existence. 



A reason for regarding these elementary substances as ultimate 

 units has been supposed to be found in their great stability, which 

 causes them to behave as if such were the case. 



While there is one possible exception to this in the case of oxygen 

 and the peculiar phenomena of ozone and antozone, it is indeed true, 

 so far as known, of all the remaining elements, that they have thus far 

 resisted all attempts to decompose them. This, however, aside from 

 the possibility of doing so still, is really no evidence of their absolutely 

 elementary character, but only indicates what the whole theory of 

 evolution would admit, if not require, that all aggregates which could 

 possess the properties requisite for the comjDosition of such masses as 

 are capable of affecting the senses, or of so affecting other masses as 

 to make themselves known to the human intellect, must possess a 

 degree of inherent stability sufficient to resist all human efforts to 

 disintegrate them. While, therefore, it is very probable that, just as 

 the alkalies and alkaline earths, which, at the beginning of the present 

 century, were regarded as elementary, have yielded to the galvanic 

 battery and proved to be composite, so a few more of those now 

 classed as elements will at no distant day be similarly decomposed by 

 the higher appliances yet to be devised ; it is nevertheless entirely 

 consonant with the view of the constitution of matter here maintained^ 

 that there shall remain ujjon the plane of human investigation a 



VOL. XTIII. 34 



