Methods of Brewing Coffee – The Vacuum Pot
In this, the second in a series of articles discussing the various ways of brewing coffee, we talk about the vacuum method or the coffee siphon as it is also known.
This technique for brewing coffee was very popular in the 1920’s through to the 1960’s but has since seen a remarkable decline to the extent that it is now very difficult to track down the apparatus needed to brew the coffee in this way.
Indeed the vacuum system was very popular in both restaurants and at home dinner parties. This was probably due to the ‘theatre’ element of watching the coffee brew before your eyes in the glass equipment together with the mesmerising movement of the liquids.
The vacuum pot apparatus consists of two glass bowls, one above the other, that fit snugly together with a glass tube extending from the top bowl into the lower bowl. The two bowls are separated by a small glass filter.
Fresh cold water is placed in the lower bowl and the upper bowl placed on top. Course ground coffee is placed in the upper bowl. Heat is applied to the lower bowl traditionally by a small spirit lamp but other heat sources can be used.
As the water in the lower chamber starts to boil, steam starts to build up in the lower bowl causing the pressure to rise. This increase in pressure causes the water to be forced into the upper bowl through the small tube that extends down where it mixes with the fresh coffee grounds. When all the water has ’siphoned’ up into the upper bowl the heat source is removed and the coffee slowly makes its way back down to the lower bowl, the glass filter removing most of the used grounds. The upper bowl is removed and the coffee served direct from the lower bowl. Usually there are some coffee grinds in the last bit of coffee so this should not be dispensed.
The vacuum pot makes a delicious brew and it’s a shame it is not still in widespread use.
The decline of the vacuum method of brewing coffee is probably due to several reasons. Heath and safety concerns no doubt contributed to its downfall. Thin glass pots, boiling liquids and naked flames on the table may have put up insurance premiums! Frequent breakages of the thin glass pots was also a deterrent to continued use as modern self-contained electric coffee machines emerged and took over.
The demise of the vacuum pot is a shame because it produces a really good quality cup of coffee. Coffee experts will tell you that to make the perfect brew, hot water just off the boil should be used. Well this is exactly what happens in the vacuum system as the water in the lower pot boils it cools slightly as it travels up the central tube until it makes contact with the coffee in the upper chamber ‘just off the boil’.
It is still possible to enjoy coffee made with the vacuum or siphon method today, although you will have to dig around on ebay or specialist shops to find the equipment.
