root beer and black cows

Just decided to post an interesting thing I have run into.  I 
have an old (undated <sniff>) Hires booklet, and it contains a 
recipe for Black Cows.  It is NOT what we think of when we 
hear that name.  Rather it is 1 tsp of Hires root beer extract 
and 2 Tbsps sugar, which are mixed and then added to 1 quart 
of milk.

I was going to say that I couldn't tell whether this was a 
powdered extract or a liquid one, but one illustration, and 
the history I have written, point to the latter.

Now I am wondering whether one can even find this in local (in 
my case, Boston-area) stores any more.  There are some other 
interesting-sounding recipes in this booklet.
-- 
Jean B.