The effect of extremely high pressures on living organisms has been studied at the Research Foundation Laboratories of Armour Institute of Technology. Here pressures of 1,500,000 pounds per square inch have been developed. Such pressures are not common in liquids or gases but are of the order of the pressure at the center of the earth which is estimated to be 3,200,000 atmospheres. In space they occur probably daily when meteoric matter, traveling with velocities of 30 miles or more a second, strikes the upper layers of the earth's atmosphere.
It was observed that a pressure of 12,000 atmospheres is necessary to kill bacteria. Bacteria are one of the simplest forms of life, and as may be expected, lesser pressures are required to destroy more complex organitms. It is expected that because of this selective effect, important deductions may be made in combatting certain pathological cases. Such forms of microscopic freshwater life as Hydra and Planaria, were found to withstand pressures from 10,000 to 20,000 pounds per square inch without any serious damage. The effect of the high pressures was to precipitate some of the colloidal constituents of the organism.
Chemical reaction between various substances was also observed under extreme pressures. The reaction be tween sugar and water was found to decrease with increase in pressure and the chemical reaction between hydrogen and sulfuric acid to give hydrogen sulfide and water. Non-sporagic bacteria do not resist above 5,000 at. On the other hand, spores and in particular those of Bacillus subtilis are able to resist pressures over 18,000 at. for a duration of 45 minutes. Evidently high pressures provide less protection against germs than other means of sterilization, such as boiling. Viruses reveal themselves as much less resistant to high pressures. At 1800 atmospheres the influence is noticeable and at 4500 at. the inactivity is complete. It is hence possible by this method to differentiate between virus and diastose.
Bacteriophages are totally inactive at a pressure varying between 2000 and 7000 atmospheres. Certain proteins, such as globuline of serum and egg white coagulate at high pressures but the albumine serum does not. A long series of research of utmost importance was inter rupted by the war; ,in the first line of these was coagulation experiments on the colloidal fluids of cancerous cells.
Important research along these lines is progressing after the interruption caused by the war.