Condensation, and on the contrast of Colors. 



83 



supposed to vary both with the drain due to the successive 

 equal exhaustions and, in the second place, to causes indepen- 

 dent of manual interference, such as are involved in the 

 motion of the nucleus (absorption by the walls, subsidence 

 when loaded, etc.) and its possible decay. It is my present 

 purpose to determine the most potent cause of dissipation. 



Accordingly, in the following experiments the effect of ex- 

 haustion is first fully treated. The large globe was partially 

 exhausted and refilled about twenty times in succession, the 

 pressures falling off from normal to about 18 cm below. The air 

 which replaced that removed was carefully filtered and the 

 influx slow enough through pressed cotton to insure efficiency. 



Table I. — Color sequences of successive 



Coronas. 



Axial colors. Residual 





nuclei. Each exhaustion from 76 cm to 58 cm . 









JV= l0»( 1 + J 0iogy ; y=-819; t = 96 sec. ; b 



= -i ; N 



= l'OOO. 





Exh. 





Axial 











No. 



Coronas. 



color. 



iVjxlO 3 



^a X 10 3 



i^xlO 3 



X/\/N 



1 



Yl fog, red rimmed 



Bl 



731 



800 



793 



1-08 



2 



Do. 



Bl 



535 



640 



629 





3 



Gray, rd, j |[ 

 Viol, rd, yl-gr 



Bl 



391 



512 



499 





4 





286 



409 



396 





5 



Bl-gr, rd 



Yl 



209 



327 



313 



1-47 



6 



Gr, prp 



Or 



153 



262 



249 





1 



Gr-yl, rd, gr, rd 



— 



112 



210 



197 





8 



Yl, or, gr, rd 



Violet 



82 



168 



156 





9 



Yl, rd, gr, prp 





60 



134 



124 





10 



Wh, prp, yl-gr, rd, gr 





44 



107 



98 



2-17 



11 



Wh, bl-gr, br-rd, gr, rd 





32 



86 



78 





12 



Apple gr, rd, buff, rd 





23 



60 



62 





13 



Gr-yl, br-rd, gr, rd 





17 



55 



49 





14 



Wh, br, gr, rd 





12 



44 



39 





15 



Wh, cr, gr, rd, gr 





9 



35 



31 



3-19 



16 



Wh,br, gr-yl j ^ 





7 



28 



24 





17 



Wh, bl-gr, rd, gr 





5 



22 



19 





18 



Yl-gr, bl, rd, gr 





4 



18 



15 





19 



Wh, br, gr, rd 





3 



14 



12 





20 



Do. Small ordinary 

 coronas 





2 



11 



10 



4*69 



With each exhaustion a corresponding amount of nuclei are 

 removed with the air. Thus after n exhaustions from pres- 

 sures p to p, the residue of nuclei should be (p/p ) n under 



isothermal, and (p/p Q y y under adiabatic conditions (7 being 

 the ratio of the specific heats), admitting what is by no means 

 the case, as will be afterwards shown, that the whole experi- 

 ment is made expeditiously enough to neglect the time loss of 

 nuclei due to the normal causes mentioned. Cf. §4. 



