NUCLEI IN WET C0 2 . 107 



In parts I to III in the table the exhaustion (dp) is usually kept con- 

 stant, with the object of observing the behavior of the mixture of gases, 

 beginning with air and terminating with C0 2 . In part I about 8 exhaus- 

 tions lead to the steady behavior of the latter gas. Inasmuch as the orig- 

 inal air is still present to the extent of about i per cent, an admixture of 

 this amount may be regarded as inappreciable. In the second part of 

 the table, even four exhaustions, reducing the air content to about n 

 per cent, nevertheless bring out the behavior of C0 2 . The same things 

 happen less certainly in part III. In part II, however, on readmitting 

 air, two exhaustions nearly suffice to restore the air corona. Parts III 

 and IV show that coronas for a given mixture are reproduced after 

 several hours. 



The relatively small coronas obtained with C0 2 as compared with air 

 for the same drop in pressure and in the same apparatus gave rise to a 

 suspicion that water nuclei associated with HC1 gas might be involved. 

 In part V, therefore, atmospheric air was bubbled through HC1 and the 

 gas then passed through the same drying train. After three exhaustions 

 exceptionally high air coronas were obtained, showing that the method 

 of producing the gas is of no consequence, thorough washing presupposed. 



Hence, in parts VI and VII of the table, the experiments with non- 

 energized CO 2 were concluded. 



In part VIII of the table the gas is ionized by the X-rays with the bulb 

 at a distance of 200 cm. The usual constancy of corona at high exhaus- 

 tions is observed, while the fog limit is exceptionally high. 



69. The behavior of carbon dioxide. The graphs corresponding to 

 table 42 are given in fig. 53, in connection with the corresponding data 

 for air, both for the non-energized and energized states. It will be seen 

 that in both cases the curves are essentially similar in their contours, but 

 that the C0 2 curves require much higher exhaustion throughout than the 

 air curves. In other words, the same coronas occur in C0 2 as in air, 

 provided that in the former gas all the pressure differences are chosen 

 to about 5 to 5^ cm. higher than in the case of air. Similar relations 

 hold for the fog limits, as was found directly by Wilson* in a different 

 apparatus. 



The peculiar feature of these results is the degree of parallelism of the 

 C0 2 and air lines, both for the non-energized and to a somewhat smaller 

 extent for the energized state. Clearly the phenomena in both cases are 

 alike in character, though lying far apart on the chart. 



70. Cause of differences. In view of the more coercible character of 

 C0 2 one would naturally expect larger colloidal nuclei than in the case 



*C. T. R. Wilson: Phil. Trans. Royal Soc, vol. 189, p. 288, etc., 1897. 



