28 Responses to The Real Origin of Viking Raids. 1  Well done! 2  Thank you for this article. 3  The shutting of the ancient trade routes to Rome and the East by the Holy Roman Empire was the principle reason that the Rus trade routes down the Volga were established. 4  Pingback: Daily Stuff 5-20-13 MjÃ¶lnir | Ancient Light's Daily Stuff.
By Anne Marie Helmenstine, Ph.D. Gunpowder or black powder is of great historical importance in chemistry. Although it can explode, its principal use is as a propellant. Gunpowder was invented by Chinese alchemists in the 9th century.Originally, it was made by mixing elemental sulfur, charcoal, and saltpeter (potassium nitrate).y Anne Marie Helmenstine, Ph.D. Gunpowder or black powder is of great historical importance in chemistry. Although it can explode, its principal use is as a propellant. Gunpowder was invented by Chinese alchemists in the 9th century.
In ancient history, if you needed serious firepower in a water fight, you had to reach for the hose. That changed 20 years ago when inventor and NASA scientist Lonnie Johnson came up with a way to use hand-pumped air pressure to power a water-gun blast. His Super Soaker would forever alter the way water wars are fought. While Johnson has since had a hand in (arguably) more important work, including a PM Breakthrough Awardâwinning method for generating electricity, he considers the powerful water gun to be one of his favorite inventions.