They are using it as an example of how something that is not otherwise eligible (the mere collocation of potassium nitrate, sulphur and charcoal) can be made eligible by limiting the claim in the way the first part of the example on slide 54 does (by limiting it to gunpowder used in a kind of firework).So if I invented gunpowder today I could not get a patent giving me a monopoly on all possible mix