Former snake oils are liniments that were at one point used and classified as snake oils. Some of these liniments are pictured and some of them even have "formerly known as snake oil" printed somewhere on them. From left to right they are:

Worner's Famous Liniment

Although this bottle does not say if it was formerly known as a snake oil, it does have a picture of a rattlesnake which implies that. It was manufactured in "Phoenix, Arizona."

Rub-In-Oil

This bottle has the exact same picture as the Worner's bottle but there's a difference. This has "That fanous pioneer liniment formerly known as snake oil" printed on the bottle. Also, towards the bottom, it reads: "Distributed by/ CHIEF WHITE HORSE/ Droster Rd./ Madison, Wis." 

Miller's Anti-Pain Oil

The third and fourth items are a box and bottle that go together. The box says, "For years called snake oil" while the bottle says, "Variously reffered to as Miller's Anti-Septic Oil" stamped into the glass, along with "Known as/ Snake/ Oil."

White Eagle's Indian Oil Liniment

The last tow items go together and were created by the White Eagle Medicine Company. The bottle has "Formerly known as snake oil" and "The old Indian remedy for Rheumatism, Stiff Joints, Inflammation, Catarrh, and Hay Fever" printed on the front. The side of the box reads, "New form adopted (January 1st 1916) formerly called White Eagle's Indian Rattle Snake Oil Liniment."

More Snake Oil exhibits:

Abe Minklier, Snake-Oil Seller	Clark Stanley	Miller's Antiseptic Oil	Rattlesnake Pete
Rattlesnake Pete's Outfits	Satirically Fake Snake Oils	Snake Man License	Snake Oil
Snake Oil Only In Name	Snake Oil Only In Name 2