Why "soft" drink?

Why are soft drinks, such as lemonade etc., called soft drinks?

Solution 1:

This made me think of why hard drinks are alcoholic. I have found that

big or hearty drink of liquor (1620s)

is probably the origin of hard liquor.

liquor: Narrowed sense of "fermented or distilled drink" (especially wine) first recorded c.1300. To liquor up "get drunk" is from 1845.

Hard meaning intoxicating, spiritous, 'strong'" sense, surprisingly, dates at least from 1879 (see edit below supporting its earlier use), from Boston Times about someone brought up on charges:

Before the court, for selling hard liquor, when he had only a licence for selling ale.

For Australia and New Zealand, it's recorded in 1890.

As for soft, "of beverages, non-alcoholic, non-spiritous," there is a citation from 1880 in the OED online, and a quote from 1891 by a brigade commander, General Robinson, that of the "Canteen" or "Post Exchange" system.

Each regiment had a "canteen" of its own, where the men could buy, at a price which would give a small profit, soft drinks, beer, cigars, pipes, etc.

There is a British Soft Drinks History devoted to soft drinks. They state that soft was first described as small, and note that a tombstone of 1764 records

Here sleeps in peace a Hampshire Grenadier,
Who caught his death by drinking cold small beer,
Soldiers be wise from his untimely fall
And when ye’re hot drink Strong or none

Edited to note: StonyB has found an 1843 book (British?) with a very interesting phrase. While reflecting on the perils of idleness, Luke Hansard states that two men could be persuades to fight (for entertainment) by use of "soft sawder" (which actually means flattery) and hard liquor. So clearly, hard for strong alcoholic beverages was in use by the early 1840s. To StonyB: Great find!

Solution 2:

I have found this article about the origin of the name:

The term “soft drink” ... is now typically used exclusively for flavored carbonated beverages. This is actually due to advertising. Flavored carbonated beverage makers were having a hard time creating national advertisements due to the fact that what you call their product varies from place to place. For instance, in parts of the United States and Canada, flavored carbonated beverages are referred to as “pop”; in other parts “soda”; in yet other parts “coke”; and there are a variety of other names commonly used as well. Then if we go international with the advertisements, in England these drinks are called “fizzy drinks”; in Ireland sometimes “minerals”. To account for the fact that they can’t refer to their product in the generic sense on national advertisements, because of these varied terms, these manufactures have chosen the term “soft drink” to be more or less a universal term for flavored carbonated beverages.

(emphasis mine)

Solution 3:

Because beverage that contain alcohol are "hard" drinks.

Consider hard cider:

In the United States and some parts of Canada, the alcoholic beverage discussed in this article is commonly known as "hard cider", while simply "cider" often refers to non-alcoholic unfiltered apple juice.