2. During the mid-20th Century, crackers were often stored in special tin containers that included a glass vial in their lids.

Question

2. During the mid-20th Century, crackers were often stored in special tin containers that included a glass vial in their lids. The glass vial contained a dehydrated hydrate that would absorb moisture from the air as it rehydrated in order to keep the crackers from going stale. The most commonly used hydrate was epsom salts but they also included an additional hydrate like cobalt (II) chloride that would change colors as it went from being dehydrated to hydrated. When you heat the vial the water in the salts evaporates, so the cracker keeper can work again. I Why do you think that an indicator like cobalt (II) chloride was included in the vial?

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