occasionally he sipped from a bottle of the famed hair tonic itself , for its alcohol content was not inconsiderable , and it was cheaper - at his distributors rate - than most domestic whiskies ( more often than not , however , arden brought him the well-received gift of a little flask of quality whisky or rum , for although he knew it was harmful to the old mans health , he figured the hair tonic must be even more injurious ) .