170 Prof. R. Bunsen on the Condensation of 



The curves show: — 



(1) That a limit of condensation is by no means reached in 

 a few hours or days, or even after several years. 



(2) During the three years' continuance of the experiments, 

 notwithstanding the sudden and gradual changes of tempera- 

 ture and pressure, no perceptible detachment of the condensed 

 carbonic acid took place from the surface of the glass. 



(3) Sudden variations of pressure of 0*3521 metre to 

 0*5696 metre, of 0*545 metre to 0*7171 metre, of 0*7168 metre 

 to 0*5355 metre, of 0*4431 metre to 0*5248 metre, gave no sign 

 of discontinuity in the progress of the condensation. 



(4) Between the intervals of temperature +23° C. and 

 — 0°*8 C. an acceleration of condensation occurred with rising 

 temperature, a diminution with falling temperature. 



(5) Including the inner surface of the apparatus, amount- 

 ing to 0*005 square metre, the glass surface had taken up 

 of carbonic acid up to the end of the 



First year, 42*91 cub. centim. at 0° and 0*76 metre, 

 Second year, 57*94 „ „ „ 



Third year, 69*98 „ „ „ 



that is, in the first year 42*91 cub. centim., in the second year 

 15*03 cub. centim., in the third year 12*04 cub. centim. 



There were condensed on 1 square metre of surface of the 

 glass in three years 5*135 cub. centim.* at 0° and 0*76 metre. 



We see that these results, deduced from three years' obser- 

 vations, are in direct contradiction to those of experiments 

 which have previously been undertaken with the same object. 

 The manner in which the earlier experiments have been car- 

 ried out easily explains the disagreement. They have been 

 conducted on the assumption that a maximum of condensa- 

 tion is attained in a few hours or days, without previously 

 removing all doubt as to the correctness of this assumption 

 by means of observations extending over a longer period. If 

 we start from the supposition which has been proved to be 

 erroneous, at any rate in the case of carbonic acid and glass, 

 the accumulations of gas would appear to be a function of 

 pressure, whereas in reality they were a function of the time. 

 With those experiments in which the spaces of time between 

 each observation have not been strictly taken into account, no 

 correct inferences can be drawn as to the dependence of gas- 

 condensation on temperature or on the magnitude of the sur- 

 faces of condensation. 



The phenomena which the condensation of carbonic acid 



* The gas still adhering to the glass threads at a pressure of 0*91) millim. 

 is disregarded in this estimation. 



