530 Prof. R. Bunsen on the Decomposition 



doubling ought to be at any particular distance from a single 

 ridge is now easily calculated from the second line of equation 

 (48), and will be actually calculated for the case of these 

 curves, and probably also for some other cases for numerical 

 illustrations, which I hope to give in Part IV. 



LXI. Decomposition of Glass by Carbon Dioxide held in 

 Solution in Capillary Films of Water* By Prof. R* 



Bunsen *. 



IN an earlier publication f I have given my investigations 

 of the phenomena which present themselves when carbon 

 dioxide is allowed to act on capillary glass threads covered 

 with an extremely thin film of moisture. According to these 

 investigations, it appears that 49'453 grammes of such capil- 

 lary threads are able in 109 days to take up so much carbon 

 dioxide, that on heating not less than 236*9 cubic centim. of 

 this gas is set free. The gas so retained in the water-film, 

 showed towards pressure and temperature precisely the rela- 

 tions which are presented in the ordinary phenomena of gas 

 absorption by liquids. In these experiments, as in all that 

 have been previously carried out, it has been assumed, both 

 from the result of direct observation and on theoretical 

 grounds, that the action of carbon dioxide on glass may be 

 entirely disregarded. And, indeed, experiments were carried 

 out in my laboratory seventeen years ago by Dr. Emmerling, 

 which showed that glass vessels in which an 11 per cent, 

 solution of hydrochloric acid was boiled for hours together 

 did not lose 0*0005 grm. in weight. If, in addition to this, 

 we bear in mind that under ordinary atmospheric pressure, at 

 15° C, water dissolves only 0*2 per cent, by weight of carbon 

 dioxide, an acid which is set free from all its compounds even 

 by the weakest acids, and, further, that repeated observations 

 show that dry carbon dioxide has practically no action upon 

 dry glass, then it must appear almost absurd to attempt to 

 explain the gradual fixation of carbon dioxide on glass dried 

 by calcium chloride by a chemical decomposition of the 

 glass. 



But the matter presents itself under quite a different aspect 

 when we have regard to the phenomena of absorption as 

 occurring in capillary films. Water which at 15° C. and 



* Translated from Wied. Ann. x. pp. 161-165 (1886), by G. H. Bailey, 

 D.Sc, Ph.D. 

 t Wied. Ann. xxiv. p. 321 (1885). 



