66 Trans. Acad. Sci. of St. Louis. 



Putting this temperature in (5), the density at the surface 

 of this sphere is 



CT 



The density of hydrogen under standard conditions 

 (0°,760""") is 0.000089578. 



The pressure at the surface due to the superposed layers 

 is, by (6), 



P = 2rfii5 = 3.706 X 10". 



This is 366,000,000 atmospheres. The density at the dis- 

 tance of one-tenth radius from the center would therefore be 

 43.2 times that of water at maximum density and the pressure 

 would be 3.66X10^° atmospheres. The density at a distance of 

 92 million miles from the center of mass would, however, 

 be 0.0000376 if the temperature of all space were ten million 

 degrees C. This is about four-tenths the density of hydro- 

 gen under standard conditions. 



The average density of the gaseous sphere being three 

 times the density at the surface, the average density of the 

 solar hydrogen sphere is 1.296. The average density of the 

 sun itself is about 1.39, or about 7 per cent, greater than 

 that of the hydrogen sphere. 



The density of hydrogen gas near the center of the sphere 

 here discussed would probably be much greater than that of 

 solid hydrogen under a pressure of one atmosphere and at its 

 fusing point. Nevertheless it is a gas, for its temperature is 

 far above the critical temperature of hydrogen. 



If a sample of it could be collected in a boiler, of adequate 

 strength and infusibility, and it were brought into our inter- 

 planetary space, in the shadow of some planet, it would cool 

 to the freezing point of hydrogen. Even then the pressure 

 on the boiler might be enormous. If the boiler be now 

 enlarged by means of a telescope joint until this pressure 

 is taken off, the boiler may be opened. It will be full of 

 solid hydrogen. The pressure of its vapors will, of course, 



