724 THE POPULAR SCIENCE MONTHLY. 



nieuts 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 B'rodie'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 hydra- 

 tion 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 gen- 

 eralization respecting the crystalloid colloid states of matter a gen- 

 eralization which, besides throwing light on many other phenomena, 

 has given us an insight into organic processes previously incompre- 

 hensible. These results, reached by his beautifully-coherent series of 

 researches extendiug 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 de- 

 velopment 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 Dur 

 ham, 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. Her- 

 schel'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 nebulae are approaching us and 

 others receding, have opened a new field of inquiry ; and the infer- 

 ences 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 gal- 

 axy. Nor must we forget how much has been done toward elucidat- 

 ing the physical constitutions of the heavenly bodies as well as their 

 motions : the natures of nebulae, 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 thun 



