OCR Text |
Show Bubble in a Sapphire There Is exhibited In the British mil-Btum mil-Btum a sapphire weighing nine carats and containing a bubble that appears and disappears with changes of temperature. tem-perature. It is believed that a cavity In the gum Incloses a quantity of carbonic car-bonic acid gas under great pressure. When the temperature Is such as to correspond with the "critical point" for the gas. under the particular pres. sure to which U Is subjected In Its brilliant prison house, It liquefies and I becomes visible as a bubble. |