One of my vintage magazines, The Household Magazine, dated April, 1936, contains an ad for a salve called Penetro. I’d never heard of the item, so naturally I had to look it up. Here’s what I found out.
The hugely successful product was manufactured in Memphis by the Plough Chemical Company (known today as Schering-Plough). It was available in drug stores until sometime in the 1950s.
Besides colds, the makers claimed Penetro cured superficial burns and scalds, bronchial irritation, cuts, scratches, sunburn, bruises, abrasion, and the list went on.
As you can see in the ad, mutton suet is the magic ingredient (sheep fat). That was combined with menthol, camphor, methyl salicylate, turpentine, oil of pine, and thymol. The suet supposedly aided the penetration of the other ingredients.
Just to clarify some of those ingredients, thymol is a white crystalline aromatic compound derived from thyme oil and other oils, or it's made synthetically, and used as an antiseptic, a fungicide, and a preservative. Turpentine oil (not to be confused with gum turpentine) is made from the resin of certain pine trees. Methyl salicylate is a compound similar to aspirin, used today in products like Ben Gay.
So, like many of the old time remedies, there were some ingredients in the compound that did indeed help some ailments. But I can't imagine putting this on burns. Ouch!