Page:Popular Science Monthly Volume 2.djvu/744

724 in special chemistry, I may single out, for their significance, the discoveries of Andrews, Tait, and especially of Brodie, respecting the constitution of ozone as an allotropic form of oxygen; and may join with these Brodie's discoveries respecting the allotropic forms of carbon, as throwing so much light on allotropy at large. And then we come to the all-important discoveries, general and special, of the late Prof. Graham. The truths he established respecting the hydration of compounds, the transpiration and the diffusion of liquids, the transpiration and the diffusion of gases, the dialysis of liquids and the dialysis of gases, and the occlusion of gases by metals, are all of them cardinal truths. And even of still greater value is his luminous generalization respecting the crystalloid colloid states of matter—a generalization which, besides throwing light on many other phenomena, has given us an insight into organic processes previously incomprehensible. These results, reached by his beautifully-coherent series of researches extending over forty years, constitute a new revelation of the properties of matter.

Neither is it true that in advancing the Concrete Sciences we have failed to do our share. Take the first in order—Astronomy. Though, for the long period during which our mathematicians were behind, Planetary Astronomy progressed but little in England, and the development of the Newtonian theory was left chiefly to other nations; yet of late there has been no want of activity. When I have named the inverse problem of perturbations and the discovery of Neptune, the honor of which we share with the French, I have called to mind an achievement sufficiently remarkable. To Sidereal Astronomy we have made great contributions. Though the conception of Wright, of Durham, respecting stellar distribution was here so little attended to that, when afterward enunciated by Kant (who knew Wright's views), and by Sir W. Herschel, it was credited to them; yet since Sir W. Herschel's time the researches in Sidereal Astronomy, by Sir John Herschel and others, have done much to further this division of the science. Quite recently the discoveries made by Mr. Huggins respecting the velocities with which certain stars and nebulæ are approaching us and others receding, have opened a new field of inquiry; and the inferences reached by Mr. Proctor respecting the "drifting" of star-groups, now found to harmonize with the results otherwise reached by Mr. Huggins, go far to help us in conceiving the constitution of our galaxy. Nor must we forget how much has been done toward elucidating the physical constitutions of the heavenly bodies as well as their motions: the natures of nebulæ, and the processes going on in sun and stars, have been greatly elucidated by Huggins, Lockyer, and others.

In Geology, the progress made here, and especially the progress in geological theory, is certainly not less—good judges say much greater—than has been made elsewhere. Just noting that English geology goes back to Ray, whose notions were far more philosophical than