"Most of the operations, which, in the ordinary way, you would imagine to be simplicity itself, require considerable dexterity and experience — in a rush trade particularly.
For example, in pouring out naturally conditioned bottled beers, which carry a sediment, such as Whitbread's, the bottle must be inverted, so that the liquor, but not the sediment, is poured into the glass, and the operation requires the service of two hands — one for the bottle, the other for the glass.
Again, the right way to serve spirits from a thimble measure, in a rush, is to hold the measure and glass in one hand, so that no liquor is lost; leaving the other free for the turning of the tap.
It is everything to have your paraphernalia to your hand; as far as possible, arranged so that you need not stoop to reach for it, e. g. cork and crown-cork extractors. Beers should carry a "head." Customers like them brilliant and clear. They must never be served dull, sick, tart, or thick. A certain lively cloudiness denotes brilliancy of condition.
In Scotland, beers are almost invariably drawn through the engine, under pressure from below, and this undoubtedly ensures better condition. Some Brewers, however, do not like the use of carbonic acid gas.
"The Art and Practice of Innkeeping" by Alexander Francis Part, published by Heinemann London, 1922, page 214.
Whitbread remained true to bottle-conditioning long after most of their rivals had gone over to artificial carbonation. Though it wouldn't last that much longer. When they bought the Forest Hill Brewery in 1924, one of the main reasons was to acquire their bottling plant, which produced artificially-carbonated beers. Long after that brewery had closed Whitbread continued to produce one of their beers: Forest Brown.
Part has some great terms for beer in poor condition: dull, sick, tart, thick.
Tart is pretty obvious. How many pints of vinegar have I been served in London. "It's supposed to taste like that. It's Real Ale." Real Sarsons, more like.
Thick I'm assuming means very cloudy beer. You know, like the stuff resembling orange juice that the kids drink nowadays.
Dull and sick I'm not so sure about. Based on stuff he wrote in the cellar chapter, where he mentions that if the cellar is too cold cask beer will become "sick", I think it means beer which hasn't had a proper secondary fermentation and conditioned properly.
The bit about Scottish pubs using gas ppressure to serve beer is a bit of a surprise. Using air pressure to serve through what looked like keg fonts was common in Scotland when I was young. I would have assumed that was what was being referred to, except that "carbonic acid gas", or CO2, is specifically mentioned.