What is the divination by barley-groats ?

In reading this page https://play.google.com/books/reader?id=BKACAAAAMAAJ&printsec=frontcover&output=reader&authuser=0&hl=ja&pg=GBS.PR34
I came across a word alphitomantis (in this page, the form is alphitomanteis).
This means the one who divines from barley meal.
And the word alphiton means barley-groats, esp. used to sprinkle over the sacrificial victim.

Now, I would like to ask what’s this divination.
And about its purpose.
Is it connected with Demeter ?