276 Dr. H. F. Weber on the Specific Heat of 



Cryohydrate of Ether, 



§ 104. Cryohydrate of Ether (?). — It is well known that when 

 water and ethylic ether are shaken together mutual but only 

 partial mixture ensues, the water taking up about one ninth of 

 its volume of ether, and the ether about one thirty-sixth of its 

 volume of water. Such an aqueous solution of ether when sub- 

 jected to cold, solidifies at —2° C, without any separation of 

 ether, into a dry solid consisting of ether and water. The com- 

 pound exhibits an interesting feature, inasmuch as it exemplifies 

 the effect of cooling on the luminosity of flame. The cryohy- 

 drate of ether may be solidified in a long test-tube, and thence 

 removed, presenting the appearance of a candle. One end of 

 this is cut off flat, and the whole placed upright on a plate. A 

 light being applied at the top, the whole melts away as the ether 

 burns. The flame is quite non-luminous. The ether is only 

 free to burn as it is in the act of melting ice, and is so cooled. 

 So it is well known that marsh-gas becomes luminous if heated 

 before combustion. Thus ether (which is empirically olefiant gas 

 plus water) and alcohol (which is empirically ether plus water) 

 have flames of luminosity the less according as their ratio of po- 

 tential water is greater. The cryohydrate of ether is in fact 

 physically, as far as its luminosity is concerned, an alcohol. 



Throughout this second part of this research I have been 

 much indebted to my friend Mr. R. Cowper for his very zealous 

 and skilful assistance. 



XXXI. The Specific Heat of the Elements Carbon, Boron, and 

 Silicon. — Part I. The Relation between the Specific Heat of 

 these Elements in the free state and the Temperature. By Dr. 

 H. Friedrich Weber, Professor of Physics and Mathematics, 

 [Concluded from p. 183.] 



B. Specific Heat of Graphite. 



KOPP has put forward the theory that all modifications of 

 carbon possess the same specific heat*; but he has not 

 tested this theory by experiment. All the forms of carbon ex- 

 cept diamond are more or less porous, and therefore absorb 

 varying quantities of gas ; hence an error is introduced in deter- 

 mining their specific heats. In order to test Kopp's hypothesis 

 I carried out the following experiments. I first of all sought to 

 determine whether any thermal change occurs when graphite 

 and water are brought into contact, the initial temperature of 

 each being the same. A piece of pure graphite weighing 3*51 



* Ann. der Chem. und Pharm. Ser. 3.j[vol. cxli. p. 121. 



