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# History of Science

2026-11-05

Time-Traveler's Guide: How to Distill 98% Concentrated Sulfuric Acid ('Mother of Industry') from Pharmacy Green Vitriol in a Clay Retort

Time-Travel Core Tech Reconstruction Guide #09. Without sulfuric acid (H₂SO₄), a time traveler cannot make nitric acid, hydrochloric acid, superphosphate fertilizer, lead-acid batteries, or smokeless powder. We break down the thermal decomposition thermodynamics of iron(II) sulfate heptahydrate (FeSO₄·7H₂O), cite Song Yingxing's 1637 Tiangong Kaiwu on 'Green Vitriol (Qingfan)', and provide a step-by-step 650°C glazed stoneware retort distillation guide.

2026-11-01

Time Traveler's Guide: When Drinking Raw Water in Ancient Times Could Kill You, How to Build a Charcoal-Alum Filter and Life-Saving ORS

[Time Traveler's Core Tech Reconstruction · Episode 05] If a modern person woke up in pre-industrial history, the deadliest threat in the first 72 hours wouldn't be swords or bandits—it would be acute dysentery or cholera dehydration from a single sip of river or well water. Grounded in colloid chemistry, slow-sand filtration, and intestinal SGLT1 sodium-glucose cotransport physiology, here is how to build a 3-layer alum-charcoal water purifier and mix Oral Rehydration Salts (ORS) using coarse salt and maltose.