Before all other stuff, you should firstly know that oil (and really all ‘dirt’ in general) predominantly consists of a group molecules dubbed ‘hydrophylic’ molecules. It’s a category that’s characterized by its stubborn immiscibility in water (immiscible means not mixable; it will never form a homogeneous, blended mixture). The simplest experiment demonstrating this principle consists of pouring oil into a glass of water and observing that the oil will linger about on top of the water, instead of dissolving and mixing in as, for example, a spoon of red kool-aid would do. The fatty molecules are inherently stable and will not form hydrogen bonds with the more unsymmetrical, electrically charged, and ’sticky’ (that is, attractive) H2O molecules (yes, I just wrote that sticky = attractive). This is why they are called hydrophobic (‘water hating’). The oil, being less dense than water, then proceeds to float to the top of the water and congregate with its equally less dense and unattractive comrades, forming a visible distinction in your little experimental glass.

This said, lets get back to our bubbles: ‘normal’ soap is composed of a mixture of two ingredients: salts (namely potassium and sodium) and fatty acids. Soap molecules are peculiar in the sense that they are paradoxically both hydrophilic and pydrophobic. Their heads, so to speak, consists of a salt atom, and their long tail is of course the fatty acid chain; the salt part is attracted to other polar substances, like water, (its hydroPHILIC) and the tail is the converse case. On using soap, the heads of many of these molecules surround whatever dirty things you are trying to rub out*, trapping it, and fan their fatty tails outward, creating a sort of contained transport vessel for the dirt. And now theres an emulsion of these conglomerations floating about in whatever aqueous solution you’re washing this stuff in.

Anyway, soap BUBBLES is the topic you’re all enraptured with. Right, well, a soap bubble, contrary to the name, isn’t composed solely of soap, but also of fat and water. This water-soap-fat concoction is what forms the envelope of the bubbles, though this is not to say that it’s a stratified bubble- there is no soap layer, then fat layer after that, etc. Rather, the soap molecules serves as an intermediary for the binding together of the three substances, like a plate of cheese snacks bringing two party guests of opposing extremist sects painlessly, and deliciously, together.  When a soap bubble is created, the air pressure inside is slightly higher than normal room pressure. The soap, by its coherent properties, forms the envelop that conserves this difference of pressure, this potential. The envelope takes a spherical form in order to minimise the amount of surface this pressure difference can affect, as well as to minimise the effort needed to keep this difference stable. Stable the bubble might be,  its charming existence is nevertheless inexorably and dramatically ephemeral.

* -_-