One of the most versatile substances on Earth, <br />Why do we always take glass for granted? <br />A wine bottle, a pickle jar, a cheap vase, <br />A window pane, all disposable and recyclable. <br /> <br />The main ingredient is common sea shore sand, <br />Chemically combined with a little soda or potash. <br />Heat resistant glass - silica - is just pure sand. <br />For cut glass, add a little lead, for coloured glass, minerals. <br /> <br />Its greatest property is its sheer transparency, <br />Transparent because it is not crystalline. <br />It is in fact a paradox - a solid solution! <br />Consequently it lets light pass clean through it! <br /> <br />Like so many important scientific discoveries, <br />Penicillin, gravity, stainless steel, purple dye, <br />The steam engine, polythene and radioactivity, <br />Glass was discovered by pure accident! <br /> <br />In antiquity, sand and wood ash, combining <br />In the embers of a fire to produce shing jewels. <br />Homo Sapiens, sifting the jewels and concluding that they <br />Must be a fusion of wood ash and sand - discovered GLASS! <br /> <br />(John Knight UK - August 2009) .<br /><br />John Knight<br /><br />http://www.poemhunter.com/poem/a-touch-of-glass/
