3451779

Information

• Patent Grant
• 3451779

• References
• Source

• Patent Number

  3,451,779

• Date Filed

  Not available

• Date Issued

  Tuesday, June 24, 1969
  55 years ago

• CPC

  • G09B3/085 - with invisibly printed correct answer; the answer being rendered visible by special optical means
  • G01N31/12 - using combustion

• US Classifications

  • 422 - Chemical apparatus and process disinfecting, deodorizing, preserving, or sterilizing
  • 073 - Measuring and testing