FOR THE ADVANCEMENT OF SCIENCE, 1857- 505 



some very general' laws of the transformation of energy, which in- 

 clude the known relations of physical forces. 



I have occupied your time so largely with the sciences of one 

 section, that I cannot do more than advert to one or two topics 

 connected with the others, which have struck my own mind, 

 although, from my limited acquaintance with the subjects, I could 

 not venture to say that they are absolutely the most deserving 

 >of notice. 



Among the most remarkable of the recent discoveries in inor- 

 ganic chemistry are those of MM. Wohler and Deville, relative to 

 silicon and boron. Each of these substances is now proved to exist 

 in three very different states, analogous to the three known states 

 of carbon, to which they are thus closely allied, namely, charcoal, 

 graphite, and diamond. The last of these states is, of course, the 

 most interesting. Crystallized boron possesses a hardness, bright- 

 ness, and refractive power, comparable to those of diamond; it 

 burns in chlorine, without residue, and under circumstances resem- 

 bling those of the combustion of diamond in oxygen ; it is not 

 acted on by any of the acids, and appears to be the least alterable 

 of all the simple bodies. I have been informed that its powder is 

 already used in the arts, instead of diamond dust ; and it seems 

 not improbable that, when obtained by the chemist in crystals of 

 larger size, it may rival the diamond as a gem. 



The science of Geology appears, of late years, to have entered 

 upon a new phase of its development, one characterized by a 

 stricter reference of its speculative views to the principles of those 

 sciences with which it is connected, and upon which it ought to be 

 based. The able memoirs of Mr. Hopkins, on what may be called 

 dynamical geology, afford a remarkable proof of this; and we have 

 another instance of the application of sound physical principles to 

 this science in the explanations which have been recently offered of 

 the phenomena of slaty cleavage. A report on this interesting 

 subject was presented to the Association by Professor Phillips at 

 its last Meeting, and will be found in the volume just published. 

 These sounder views Originate, I believe, with himself and with 

 Mr. Sharpe ; but they have been enlarged and confirmed by Mr. 

 Sorby, Dr. Tyndall, and Professor Haughton. 



