THE 



LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



MARCH 1884. 



XXII. On the Condensation of Carbonic Acid on Smooth Glass 

 Surfaces. By R. Bunsen*. 



[Plate V.] 



THE thickness of the layer of carbonic-acid gas condensed 

 on glass surfaces is, as is known, so small that a very 

 extensive surface is necessary to allow of its exact estimation. 

 The material best adapted for giving such an extension of 

 surface in the least possible ' space is the extremely fine spun 

 glass which is used in glass-weaving. The threads made use 

 of in the following experiments were of such fineness that 

 150 grms. only occupied a space of 100 cub. centim., and cor- 

 responded to a length of 62 geographical miles, giving a 

 surface of 23 square metres. The composition of the glass 



was : — 



Si0 2 . Na 2 0. K 2 0. CaO. MgO. Al 2 3 . FeO. 



70*65 16-01 2-07 8*96 027 186 0*68 

 The estimation of the specific gravity of the thread enters 

 into the computation of its surface, and was made as follows: — 

 A number of grammes were weighed out in a platinum dish 

 which was filled with well-boiled water and kept boiling till 

 the last traces of air were removed ; when cold the dish with 

 its contents. was suspended by a hair in boiled water at a con- 

 stant temperature and weighed ; in the same way the loss of 

 weight was estimated when the glass threads were removed, 

 the weighing being made in water, as before, at constant 

 temperature. 



* Translated from Wiedemann's Annalen, vol. xx. p. 545, by G. H. 

 Bailey, B.Sc, The Owens College. 



Phil. Mag. S. 5. Vol. 17. No. 105. March 1884. M 



