http://www.merlot.org:80/merlot/ A search of MERLOT materials Copyright 1997-2013 MERLOT. All rights reserved. Sun, 19 May 2013 19:18:03 PDT Sun, 19 May 2013 19:18:03 PDT http://www.merlot.org:80/merlot/images/merlot.gif http://www.merlot.org:80/merlot/ 44 34 http://www.merlot.org/merlot/viewMaterial.htm?id=759089 Primary resource wherein Joseph Priestley defends the theory of Phlogiston, and attempts to falsify theories of combustion, oxygen, and elements, or "the new system of chemistry״. This letter was written in 1796. http://www.merlot.org/merlot/viewMaterial.htm?id=735047 A detailed analysis of buoyancy in the context of Felix Baumgartner's historic jump from 39 km altitude as the culminating event of the Red Bull Stratos mission. Buoyancy was provided by a helium-filled balloon that made the equipment less dense overall from the surrounding air.This article takes readers through the calculation of the density of the relevant gases (air and helium) and the net density of the ascent equipment. An error analysis shows that helium and air must have counter-diffused through the balloon wall and estimates the composition in the balloon. Also discussed are possible reasons for why the ascent equipment achieved a greater altitude than expected.