Mixers

A standard South African tot is 25 millilitres. Fill the rest of a highball with 150 or 200 millilitres of tonic or soda and the spirit accounts for well under a fifth of the liquid in front of you. Everything else is water, gas, sugar and acid. That has an obvious consequence which almost nobody acts on: swapping one tonic for another changes the drink far more than swapping one gin for another, and yet the gin is where nearly all of the attention goes.

Dissolved carbon dioxide leaves the liquid as bubbles, and it carries aroma with it on the way out. That is why a fresh pour smells sharper than the same glass twenty minutes later. Carbonation also reads on the tongue as a slight prickle, so a fizzy mixer tastes drier than a flat one built on identical sugar.

Almost every mixer is built from some combination of sweetness, fruit or phosphoric acid, and a bitter note. Cola leans sweet with a sharp acid edge behind it. Soda water brings none of the three and simply lengthens the drink. Tonic is the only common mixer built around bitterness, which is why it suits juniper-heavy spirits and sits awkwardly with sweeter ones.

Cold liquid holds dissolved gas better than warm liquid, so a mixer straight from the fridge stays lively for longer. A room-temperature mixer poured over ice fizzes hard, loses much of its gas in seconds and melts the ice faster. Chill the mixer and the glass, and let the ice hold the temperature rather than create it.

Juice behaves differently from a carbonated mixer. It brings body and sugar but no lift, so a drink built on juice sits heavier and warms faster in the glass. Fresh citrus juice also dulls within hours of being squeezed, while a sealed carbonated mixer is the same on day thirty as on day one. If you are mixing with juice, make smaller drinks and make them closer to when you plan to drink them.

No. Brand pairings are marketing rather than chemistry. What matters is style: a dry, juniper-forward gin wants a plain Indian tonic, while a sweeter spirit is better with something less bitter. Taste the mixer on its own first. If you would not drink it by itself, it will not improve once there is a spirit in it.