h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Soap is a doddle to make. All you need is a source of fatty acids. Like a dead cow (these are very common in the UK just now). So what you need to do is render down your dead cow in a big pan over a low heat. Separate off the fat from the soup. Eat soup. Add aqueous sodium hydroxide to fat and cook. Hey presto you have made soap. You may now use it to wash the soup dribbles off your shirt. Dirty boy.

love

dave

You just watched fight club.... Didnt you!

Still its all true...

I was about to say the same thing! (Re: New entry into Popular Culture...)

Any mention of making soap = Fight Club = Study of modern popular culture = Life imitates art = Art imitates life = Cat hovers, spinning, with slice of buttered toast tied to back = perpetuality = Esso go out of business (Yay!)

Hi there to all you wise 'soap stars'. You Dave (170621) seem to know the where and whyfores of soap construction, but can you or someone please explain to me what is the germicidal content and how it is introduced and retained in a block of hand soap, or a jar of liquid soap. We were always told as kids that soap washes the germs away.
Regards,
Ever curious
Researcher 205898.

germicidal simply implies that something will kiil germs which I would class as harmful bacteria. Soaps are surfactants and not necessarily poisonous to germs/bacteria, however they can be.

Personally I am not in favour of the current mass use of germicides i soap as it worries me we will eventually breed resistant strains of bacteria. I never use them. We survived quite well without them.

sorry for delay. I have not been on here for a while.

Soap is, itself germicidal. When we refer to "germs", we are generally speaking of bacteria. Bacteria are single-celled organisms covered by a cell membrane consisting of a two-layered sheet of lipids. The lipid molecules are long and contain hydrophilic "heads" and hydrophobic tails. Since bacteria live in an aqueous world, the molecules composing the cell membrane line up with the heads all sticking out toward the water (either toward the outside or the inside of the cell) and the tails line up inside the cell membrane, where they happily avoid exposure to water. They are exposed to various proteins that live in the cell membrane performing various functions, and tend to float by on occasion. These proteins serve a variety of functions, but tend to remain in the cell membranes because they too have hydrophobic portions, that remain inside the cell membrane and hydrophilic portions that project outside the membrane.

Soap disrupts a bacteria's cell membrane by attracting the hydrophobic tails, almost turning parts of the membrane inside out. The lipids happily float away with the hydrophobic tails bound to the soap and the hydrophilic heads floating contentedly in the surrounding water. The cell membrane dissolves and the bacteria ruptures and dies.

Now, if your "germs" happen to include viruses, then you are playing on a new level of the field. Viruses do not have a cell membrane per se, partly because they're not even cells. In fact, they're generally constructed of coat made of protein with either DNA or RNA and perhaps a few enzymes inside. Fortunately, most viral coats tend to dissolve in simple household bleach. If one wishes to add virus-killing power to one's soap, one need only add bleach, which can be made to "dissolve" in soap readily.

alternatively, you could just dip your finger in NaOH soln and hey presto, skin soap! (but i dont recomend it. experience tells me that <0.5M is pretty harmless)

when rendering the cow do you just throw the whole cow in a pan? cause im having a very hard time finding a cow sized pan