Table 1: Critical relative humidities of pure salts at 30 C.

Table salt, in contrast to "pure" salt contains a small amount of silicon dioxide, to prevent clumping.

Absolutely unique with so much pure white salt under your feet that walking barefoot on the edge is really difficult.

Others filled cups with salt so pure that they used it rather than other mixtures.

Once boiled, a yellow layer is formed - this is scraped off leaving absolutely pure salt.

Salt was an important item of trade, but pure salt was relatively expensive.

The rest of the year, the waters turn into pure salt.

An extra pound of pure salt refined from the harvest would justify the added hours of hiking.

But when that batch was gone, so was the obscure impurity, and Jekyll had only pure salts.

During more modern times, it became more profitable to sell salted food than pure salt.