6 parts oak bark,
3 parts marshmallow root,
3 parts mullein herb,
2 parts Wormwood ,
1 part lobelia,
1 part scullcap,
6 parts comfrey root,
3 parts walnut bark (or leaves),
3 parts gravel root
It's in the Newsletters (Volume 1 Number 8) of "The Complete Writings of Dr. John R. Christopher" CD.
Unyquity also makes a superb BF&C oil. I'm sure it's one of the best BF&C products available.
From what I understand, and I'm sure you guessed, BF&C is most effective if taken internally and externally. The tincture doesn't taste too bad.