324 Prof. F. Ztillner on the Temperature and 



10' 



these values in equation (II.), we get — =22*1; that is, the 



Pa 



pressure in the interior of the space from which the protube- 

 rances issue is 22*1 times as great as the pressure on the surface 

 of the liquid dividing-layer. If we next substitute the value of 

 t in formula (IV.), and take, as before, the value of h to be 8", 



we have — 766000 for the relation between the pressure at the 

 Ph 



liquid surface of the sun to the pressure at the elevation h, where 

 the hydrogen spectrum begins to be continuous owing to the in- 

 crease of pressure. If we substitute for p h the above value of 

 0*180 metre of mercury, we have for p a = 184000 atmospheres, 

 and for jt?j= 4,070,000 atmospheres. 



If we next calculate the depth in the liquid body of the sun 

 having a specific gravity of 1*46, at which, in consequence of the 

 hydrostatic pressure, the maximum pressure of p t is attained, we 

 find that this is reached at a depth of 139 geographical miles 

 from the surface— that is, at a depth of 1*46 second, or one 658th 

 part of the sun's semidiameter. Even if, not considering the 

 liquid condition, and under the assumption of a much greater 

 thickness of the atmosphere of hydrogen, we calculate the depth 

 at which the atmospheric pressure becomes equal to the internal 

 pressure pi, it appears that when the temperature is as high as 

 68400° the point is reached at a depth of only 27" under the 

 visible surface of the sun, or at about ■£$ of its visible semi- 

 diameter. 



This shows how rapidly the pressure must increase towards 

 the interior of the sun's body ; and it renders plausible the sup- 

 position that in the interior of the sun, in spite of the high tem- 

 peratures which there exist, the permanent gases such as hydro- 

 gen can only exist in the condition of glowing liquids. 



§5. 



A very singular result is obtained if we assume an atmosphere 

 of nitrogen or oxygen of the same weight and temperature as 

 was the case with the hydrogen atmosphere which we have just 

 considered, and then calculate the pressure which will occur in 

 that atmosphere at the elevation at which the hydrogen spectrum 

 begins to be continuous. If we suppose that the pressure on 

 these three atmospheres of hydrogen, nitrogen, and oxygen is 

 the same at a depth of 8" below the visible edge of the sun's 

 disk or at the level of the supposed layer of division, and that 

 this common pressure is /> a = 184000 atmospheres, which, ac- 

 cording to the foregoing, corresponds to the assumed value of p h , 

 we obtain, when the temperature t= 27700°, for the pressure of 



