Paraffin (isn't that wax?) in the gasoline? It got me curious, and simultaneously a comment with the answer while I was looking it up, but the British and some other countries refer to Kerosene as Paraffin
How does a button intensify the spark? Added resistance = high voltage? (E=IR voltage equals current times resistance... Ohms Law of electricity)
Putting cream in a tire with a hole in it can stop the leak? I don't think so. I was wrong!
Steve (that craza guy! (with a Borat accent)) found the back of this card (!)
You remove the valve core and funnel in the milk as shown on the card you posted. A few things combine to make leak stoppage happen. At normal temps milk starts to sour fairly quickly and the heat generated by the tire as it rolls hastens the souring. The rolling tire acts as a bit of a churn, and the heat also helps the water in the milk to separate and some water out the puncture or poorly seated bead, and some evaporates sort of like the propellant in products like Fix-A-Flat. As the milk goes bad, churns, and loses water, it thickens and forms small chunks of milk fat - sort of like a butter/cheese mix. As the soured milk squishes out the hole, it carries along bits of the milk fat, which eventually plug small holes such as those made by thorns and the like - things that cause slow leaks that flatten a tire over a period of several days.
Some bicyclists carry a can of condensed milk (Pet, Carnation, etc,) to use, even though it in the same way. Most of the water is already gone and the remaining liquid is nearly the same consistency and look as commercial sealants (thick and sticky). While the souring factor is much less, the solids are more concentrated and it seems to work faster. Plus it has the advantage of smelling sweet when you dismount the tire - instead of rancid - and the sticky film left inside is easily wiped off with a wet towel.
This might put the hold on something but as soon as you go to lever the object you are pinching between a jack and the car frame, I bet it spins out and you get a sudden drop of the car onto the jack.
From Lambert and Butler “Hints and Tips for Motorists” Cigarette Cards from 1932
http://flashbak.com/25-lambert-butler-hints-and-tips-for-motorists-cigarette-cards-from-1932-34062/
