Madame Vassieux of Lyons is responsible for developing the vacuum pot during the 1840's. Technically these pots are known as Hydropneumatique (Hydropneumatic) pot. This type of pot was in use right up through the 1960's; and Silex produced a vacuum pot in the USA until the mid 1900's.
Another name synonymous with vacuum coffee pots is Madame Richard. While percolators and vacuum pots were introduced around the same time, there is a big difference between them. In both, the water is pumped into the upper compartment. In this process, the coffee is being brewed at the correct temperature. The vacuum pot utilizes steam from the heated water. This steam rises through the glass tube into the top to the infusion chamber. There it condenses and mixes with the coffee grinds. Removed from the heat, the vacuum presure sucks the brewed coffee back down into the lower bowl/serving carafe. The top bowl is then removed to allow you to pour from the serving carafe. This allows the temperature of the steam to be better controlled, which is felt to be a vital component in brewing coffee properly.
The vacuum coffee pot had several problems. One serious problem was maintaining pressure. While most vacuum pots were glass, metal pots were available. People, however, liked to watch the coffee brew, making glass the more favorable pot. However, there is a problem with glass and steam. Additionally, glass in the old days was not all that strong and pots were known to blow up. Despite the danger glass remained more popular. Spring safety valves and tilt pour spouts got patents, in an effort to ensure the safety of the operator. Some had special tops which could be removed, thus allowing the coffee to remain in the top, producing a stronger taste.
The main objective of the vacuum pot was to heat the water and brew the coffee at the same time. Another benefit of the vacuum pot was the size and location of the filter. It fit in the neck between the upper brewing bowl and the lower boiling/serving pot. This reduced costs as it could be thrown away and was not expensive in the first place. The Raparlier vacuum pot (1859) possessed a glass upper bowl on which a cup gradation was marked in order to determine how much coffee was brewed. In the Raparlier pot, the filter was made from hemp (a plant generally outlawed these days). It was easily rapped around in the filter neck, could be pulled out easily, and thrown away after each use. It beat using the traditional old sock as a filter.
Later types of vacuum pots utilized the innovation of putting the two bowls side by side. This became known as the balanced beam coffee pot. The balanced beam vacuum pot worked on the same theory as the vertical vacuum pot. However when the brew filled the brew bowl, a weight changed pulling a device putting out the heat source. This was true automation.
Many connoisseurs of coffee recommend using only glassware with no metal products which may come in contact with the coffee. It is thought this will produce the most excellent, sediment-free brew. While these pots were invented over 160 years ago, they are starting to gain popularity again, and several manufacturers are beginning to add them to product lines. Among them are Santos® and Silex®.
Information above was gathered, in part, at the following websites:
http://www.rappahannockcoffee.com/drinks/index2.html