The Natron Theory
Once upon a time there was a desert. And in this desert, where logically nothing should happen, here humanity made its most important steps in development. 
In the beginning there was ... natron
Natron is a kind of salt which is abundant in the Nile valley. People have been hand-picking and collecting it in baskets since ancient times. Ancient Egyptians used natron for at least ten different purposes: 
  • Washing clothes, drying food, medical treatment, mouthwashing, ceramics, textile dyeing, insepticide, conserve papyrus, cosmetic and...
  • Mummification, of course
Oh, and one more thing!
Natron was also used to create glass. So called "natron glass", which is still the most common format of glass we use today. In fact, this happened way before the Egyptians even dreamed of having an empire. Between 5000 and 4000 BC they already created small glass amulets and glass beads*.
*Badarian culture
What is glass, and why is it important?
Natron glass is nothing more than natron, sand and limestone "cooked" together on 851 degrees Celsius. Which means ​Egyptians were able to melt natron since the beginning of time**.
**It's a - so called - "fact"
Now tell me straight to my face, are you seriously saying that normal, healthy ancient men didn't try melting stones with molten natron, but only bothered with sand?