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# Time Traveler Guide

2026-11-08

Time-Traveler's Guide: Walls Collapse in Heavy Rain? How to Burn Modern Portland Cement from Limestone and River Clay

If you travel back to antiquity, why do mud-brick houses collapse in rainstorms while sticky-rice lime mortar takes decades to cure and dissolves underwater? Here is the complete inorganic chemistry and 1400°C shaft-kiln guide to making hydraulic Portland cement from 3 parts limestone and 1 part river clay.

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.