Today in 1976, US Patent 3979527 A was issued, an invention of Derek Roy, James Laws, and John Anthony Pickett, assigned to Brewing Patents Limited, for their “Preparation Of Hop Oil.” Here’s the Abstract:

An improved method of making hop oil is described involving steam distilling the hop oil under vacuum at a temperature not exceeding 50°C. The distillate can be collected by cooling to less than -20°C. The collected distillate or hop oil extracted therefrom can be used in beer making processes to give beer having a hop character very similar to that obtained by dry hopping.