What is "to scrape acquaintance"

Scrape \Scrape\ (skr[=a]p), v. t. [imp. & p. p. Scraped; p. pr. & vb. n. Scraping.] [Icel. skrapa; akin to Sw. skrapa, Dan. skrabe, D. schrapen, schrabben, G. schrappen, and prob. to E. sharp.]

1. To rub over the surface of (something) with a sharp or rough instrument; to rub over with something that roughens by removing portions of the surface; to grate harshly over; to abrade; to make even, or bring to a required condition or form, by moving the sharp edge of an instrument breadthwise over the surface with pressure, cutting away excesses and superfluous parts; to make smooth or clean; as, to scrape a bone with a knife; to scrape a metal plate to an even surface.

2. To remove by rubbing or scraping (in the sense above).

   I will also scrape her dust from her, and make her like the top of a rock.
   --Ezek. xxvi. 4.

3. To collect by, or as by, a process of scraping; to gather in small portions by laborious effort; hence, to acquire avariciously and save penuriously; -- often followed by together or up; as, to scrape money together.

   The prelatical party complained that, to swell a number the nonconformists did not choose, but scrape, subscribers.
   --Fuller.

4. To express disapprobation of, as a play, or to silence, as a speaker, by drawing the feet back and forth upon the floor; -- usually with down.
   --Macaulay.

   To scrape acquaintance, to seek acquaintance otherwise than by an introduction.
   --Farquhar.

   He tried to scrape acquaintance with her, but failed ignominiously.
   --G. W. Cable.