lather vs soap powder

lather

verb
  • To form lather or froth, as a horse does when profusely sweating. 

  • To cover with lather. 

  • To beat or whip. 

noun
  • A state of agitation. 

  • The foam made by rapidly stirring soap and water. 

  • Foam from profuse sweating, as of a horse. 

soap powder

How often have the words lather and soap powder occurred in a corpus of books? (source: Google Ngram Viewer )