What is "air-slacked lime"

Slack \Slack\, Slacken \Slack"en\, v. t.

1. To render slack; to make less tense or firm; as, to slack a rope; to slacken a bandage.
   --Wycklif (Acts xxvii. 40)

2. To neglect; to be remiss in. [Obs.]
   --Shak.

   Slack not the pressage.
   --Dryden.

3. To deprive of cohesion by combining chemically with water; to slake; as, to slack lime.

4. To cause to become less eager; to repress; to make slow or less rapid; to retard; as, to slacken pursuit; to slacken industry. ``Rancor for to slack.''
   --Chaucer.

   I should be grieved, young prince, to think my presence Unbent your thoughts, and slackened 'em to arms.
   --Addison.

   In this business of growing rich, poor men should slack their pace.
   --South.

   With such delay Well plased, they slack their course.
   --Milton.

5. To cause to become less intense; to mitigate; to abate; to ease.

   To respite, or deceive, or slack thy pain Of this ill mansion.
   --Milton.

   Air-slacked lime, lime slacked by exposure to the air, in consequence of the absorption of carton dioxide and water, by which it is converted into carbonate of lime and hydrate of lime.