322 Prof. F. Zollner on the Temperature and 



According to the mechanical theory of heat, such velocities in 

 the case of hydrogen necessitate a difference of temperature 

 amounting to 40690° C. The temperatures themselves may be 

 approximately determined if we can succeed in obtaining any 

 limiting value for t } the temperature of the outer atmosphere of 

 hydrogen. This temperature, as has been already shown, may- 

 be taken to be nearly identical with that in the neighbourhood 

 of the outlet. 



§4. 



A limiting value for t may be obtained from equation (V.), 



bph ( a + t \ 

 a+t \ t ) 



rh 



<J 

 e"\r+h)t. 



In this the density a of the enclosed mass of gas is expressed as 

 a function of the three values p h , h, and t. I shall now show 

 that the value of a cannot exceed a certain limit ; and thus the 

 value of t is also ascertained within a given limit, inasmuch as 

 limits to the values p h and h have been already determined. It 

 has been already pointed out that the explanation of the eruptive 

 protuberances presupposes the existence of a layer of separation, 

 dividing the space out of which the eruptions break forth from 

 that into which they empty themselves. It is only by the exist- 

 ence of such a division that the required difference in pressure is 

 rendered possible. 



Respecting the physical constitution of this layer, the further 

 assumption is necessary that it is in some other state than the 

 gaseous. It may be either solid or liquid. In consequence of 

 the high temperature the solid state is excluded ; and we must 

 therefore conclude that the layer of division consists of an incan- 

 descent liquid. 



Respecting the mass of hydrogen enclosed by this liquid 

 layer, two suppositions appear at first sight possible : — 



1. The whole interior of the sun is tilled with glowing hy- 

 drogen, and our luminary would appear like a great bubble of 

 hydrogen surrounded by an incandescent atmosphere. 



2. The masses of hydrogen which are thrown out in these vol- 

 canic outbursts are local aggregations contained in hollow spaces 

 formed near the surface of an incandescent liquid mass, and 

 these burst through their outer shell when the increased pressure 

 of the material in the interior reaches a certain point. 



According to the first assumption, a state of stable equilibrium 

 will only occur when the specific gravity of the liquid dividing 

 layer is smaller than that of the gaseous layer which lies imme- 

 diately underneath it. As, however, the density of a gaseous 

 globe, whose particles obey the laws of Newton and Mariotte, 



