## Thursday ### Mepacrine [Mepacrine](https://en.wikipedia.org/wiki/Mepacrine) is an anti-malaria drug. It has a side effect of turning your skin yellowish. American [[spies]] in [[World War II]] in [[China]] would use it to blend in. (via [Astral Codex Ten](https://www.astralcodexten.com/p/links-for-july-2024)) ### [[Library of Congress]] A short article on the [Library of Congress](https://www.scientificamerican.com/article/how-does-the-worlds-largest-library-decide-what-becomes-history/)[°](https://elliotclowes.com/cold/2024/https__www.scientificamerican.com_article_how-does-the-worlds-largest-library-decide-what-becomes-history_.html) and how and why they choose things to archive. There was a law in [[Alexandria]] where any traveler's who arrived in the city hand to hand over their books to [[Library of Alexandria]] scribes. They would make a copy and give the traveler the copy, not the original! As of [[2024]] they have 184 PB of data. I find it interesting how writers still use DVDs/CDs to illustrate how much a certain amount of data is. It feels rather outdated. At this point people should understand what a terabyte and petabyte is. > Along with physical media, as of 2024, the library held about 184 petabytes of digital information, from three-dimensional digitized artifacts to patents. Converted into DVDs, that would be about 39 million disks. And if those disks were stacked atop one another, they would tower 29 miles high—a span equivalent to about 106 Empire State Buildings. They have 'field offices': > We also have six field offices of the library—in Cairo, Egypt, Islamabad, Pakistan, New Delhi, India, Jakarta, Indonesia, and Rio de Janeiro, Brazil. All exciting, exotic locations. It feels very [[Indiana Jones]] to me. ### [[Decaffeinated Coffee]] Notes from this: [[Article — Retaining flavor while removing caffeine − a chemist explains the chemistry behind deca...]] Apparently decaffeinated [[coffee]] still has around 7 mg of caffeine per 236 ml up of coffee. That's higher than I was expecting. There is three ways to decaffeinate coffee. The same methods are use for decaffeinated tea too. The method is done on unroasted beans, not roasted ones. It's chemically impossible to dissolve only the caffeine and not other chemical compounds. To get around this some methods reintroduce the flavourful chemical compounds after the caffeine has been extracted. #### Carbon dioxide method - Developed in the [[1970s]]. - The moisten the beans. - CO₂ is pumped into a vessel with the beans and caffeine molecules dissolve in the CO₂. - The beans are then dried, which removes any leftover CO₂. - It requires expensive equipment. So is used by commercial suppliers or supermarkets. #### Swiss water process - Developed in the [[1980s]]. - The beans are soaked in hot water which extracts the caffeine and other compounds. - As there's more caffeine in the beans than the water it moves into the water. - The beans are then put into new water and the process repeats, up to 10 times until there's almost no caffeine left. - The water is then passed through activated charcoal filters. They trap caffeine and other compounds. - The water, full of flavour, but devoid of caffeine is then soaked in the decaffeinated beans to give them the flavour they lost. #### Solvent-based methods - Simple really. The beans are left in solvents to get rid of the caffeine. Often ethyl acetate and methylene chloride.