The Collaborative International Dictionary of English v.0.48:

Sadden \Sad"den\, v. t. [imp. & p. p. Saddened; p. pr. & vb.
   n. Saddening.]
   To make sad. Specifically:
   (a) To render heavy or cohesive. [Obs.]
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             Marl is binding, and saddening of land is the great
             prejudice it doth to clay lands.     --Mortimer.
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   (b) To make dull- or sad-colored, as cloth.
   (c) To make grave or serious; to make melancholy or
       sorrowful.
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             Her gloomy presence saddens all the scene. --Pope.
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