/oss/taxonomy/term/2219/all en /oss/article/technology-general-science/connection-between-frosted-lightbulbs-bad-pick-lines <p>Way back in 1771, Swedish chemist Karl Wilhelm Scheele was investigating the properties of a mineral known as fluorspar (calcium fluoride). He mixed the pulverized rock with sulfuric acid and heated the mixture. The results were literally staggering! Scheele practically choked on the vapours that were produced, but he survived to make a dramatic discovery. The clear glass vessel in which he had combined the fluorspar and sulfuric acid had become cloudy. This cloudiness, was the glass having partially dissolved! How did this happen?</p> Wed, 22 May 2019 03:11:53 +0000 Joe Schwarcz PhD 7775 at /oss /oss/article/did-you-know/why-do-lightbulbs-develop-sediment-age <p>Have you ever wondered why tungsten light bulbs develop a black deposit as they age? This deposit is metallic tungsten, the same stuff that the filament is made of. A lightbulb produces heat and light when an electric current passes through a resistance. In this case, the resistance is a tungsten filament. Tungsten is close to ideal for a filament because it has a very high melting point and does not evaporate easily.  Nevertheless, small amounts of tungsten do evaporate and condense on the cooler glass surface. As more and more tungsten evaporates, the filament gets thinner and the glass g</p> Tue, 21 Feb 2017 16:29:07 +0000 Joe Schwarcz PhD 1514 at /oss