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Show 18 CONSTITUENT MATERIALS OJ!~ THE EAR'l'H, Ya.nce from law to the cause of law, and ask, What is that.? Whence have come all these beautiful regulations? Here science leaves us, but only to conclude, from other grounds, that there is a First Cause to 'vhich all others are secondary and ministrative, a primitive almighty will, of which these laws are merely the mandates. That great Being, who shall say where is his dwelling-place, or what his history ! Man pauses breathless at the contemplation of a subject so much above his finite faculties, and only can wonde1· and adore ! CONSTITUENT MATERIALS OF THE EARTH, AND OF THE OTHER BODIES OF SPACE. THE nebular hypothesis almost necessarily supposes matter to have originally formed one mass. We have seen that the same physical laws preside over the whole. Are we also to presume that the constitution of the whole was uniform ?-that is to say, that the 'vhole consisted of similar elements. It seems difficult to avoid coming to this conclu~ion, at least under the qualification that, possibly, various bodies, under peculiar circumstances, attending their formation, may contain elements which are wanting, and lack some which are present, in others, or that smne may entirely consist of elements in which others are entirely deficient. What are elements ? This is a term applied by the chemist to a certain limited. number of substances (fiftyfour or fifty-five are ascertained,) which, in their combinations, form all the matters of every kind present in and about our globe. They are called elemtnts, or simple substances, because it has hitherto been found impossible to reduce them into others, wherefore they are presumed to be the p~·irnary bases of all matters. It has, indeed, been surmised that these so-called elements are only modifications of a primordial form of matter, brought about under certain conditions; but if this should prove to be the case,.it would liltle afiect the view which we are taking of cosmical arrangements. Analogy would l~ad us to conclude that the combinations of the primordial matter, forming our so-called elements, are ns unj. AND OJ!' THE OTHER BODIES OF BF.ACE. 19 versal, or as liable to take place everywhere, as are the laws of gravitation and centrifugal force. \Ve n1ust therefore presume that the gases, t.he metals, the earthg, and other simple substances (besides whatever more of which we have no acquaintance) exist, or are liable to come into existence under proper conditions, as well in the astral system, which is thirty-five thousand times more distant than Sirius, as 'vithin the bounds of our own solar system or our own glob~. Matter, whether it consists of about fifty-five ingredients, or only one, i!; liable to infinite varities of condition nder different circumstances, or to speak more philosophically under different laws. As a familiar illustration, water, when subjected to a temperature under 32° Fahrenheit, becomes ice; raise the temperature to 212° and it becomes steam, occupying a vast deal more space than it formerly did. The gasses, when subjected to pressure beco11e liquids; for example, carbonic acid gas, when subjt~cted to a weight equal to a column of water 1230 feet high, at a temperature of 32°, takes this form; the other gasses require various amounts of pressure for this transformation, but all appear to be liable to it when the pressure proper in each case is administered. Heat is a power greatly concerned in regulating the volume and other conditions of matter. A chemist can reckon with considerable precision what additional amount of heat would be required to evaporize all the water of our globe; how much more to disengage the oxygen which is diffused in nearly a proportion of one-half throughout its solids; and, finally, how much more would be required to cause the whole to become vaporiform, which we may consider as equivalent to its being restored to its original nebulous state. He can calculate with equal certainty what would be the effect of a considerat le diminution of the earth's temperature-what changes would take place in each of its component substances, and how much the whole would shrink in bulle The earth and all its various substances have at present a certain volume in consequence of the temperature which actually exists. When, then, w·e find that its matter and that of the associate planetR, was at one time diffused throughout the whole space now circumscribed by the orbit of Uranus, we cannot doubt, after '""hat we kuow of the power of heat, that the nebulous fm;m of matter was at- |