I don't use them, but they get mentioned a lot and I got curious.

The patent formula I found says they are basically rubbing alcohol, tincture of green soap, glycerin and violin rosin.

If you aren't familiar with tincture of green soap, it used to be used as a medical scrub/disinfectant.  They might still use it, for all I know.  But it is basically just mild soap dissolved in rubbing alcohol with glycerin and usually a dash of lavender oil for scent.  Notice that most of the ingredients other than the soap and the scent are already in the peg drops ingredients anyway.

I found it kind of interesting, since I have seen advice in assorted places online advising against using rosin or soap as a remedy for slipping pegs and sometimes advising using peg drops instead.  But after the alcohol evaporates, soap and rosin are what are mostly going to be left. 

to see the patent info, scroll down this page past the assorted links:  http://www.freepatentsonline.c.....82527.html