Blowpipe (tool)

From Wikipedia, the free encyclopedia

The Blowpipe is a narrow tube by means of which a stream or jet of air or a specific gas or gas mix can be directed onto a flame to concentrate or increase heat. Jewelers and glassmakers have used the blowpipe since ancient times, with the blast being powered by the user's lungs. From the 1800s onwards, blowpipes, gas blowpipes - the distinction being the use of oxygen or hydrogen or mixtures thereof - have been powered by bladders and bellows, and later by gas cylinders and mechanical blowers. Contemporary oxy-fuel welding and cutting is a modern development from the blowpipe.

In chemistry and mineralogy it has been used as scientific instrument for the analysis of small samples since about 1738, according to the accounts of Torbern Bergman. One Andreas Swab, a Swedish mettalurgist and Counsellor of the College of mines is credited with the first use of the blowpipe for 'pyrognostic operations', of which no record remains. According to Griffin (1827), the next person of eminence who used the blowpipe was Axel Fredrik Cronstedt, who put it to the purpose of the discrimination of minerals by means of fusible reagents. In 1770 an English translation of Cronstedt's work was made by Von Engestrom, annexed to which was a treatise on the blowpipe. Despite this opening, assay by blowpipe was for the time an occupation undertaken for the most part in Sweden. Bergman's use of the blowpipe outstripped all of his predecessors, and he widened its application from mineralogy to inorganic chemistry, giving rise to what may be regarded as a masterpiece of philisophical investigation, De Tubo Ferruminatorio, published in Vienna in 1779 (and translated into English in 1788). Bergman's assistant, Assessor Gahn, is next credited with moving the design and application of the blowpipe on. Gahn travelled with a portable blowpipe, applying it to every kind of chemical and mineralogical enquiry, such as proving the presence of copper in the ashes of vegetables. Gahn published a Treatise on the Blowpipe, which was reprinted a number of times in contemporary chemistry textbooks. Jöns Jakob Berzelius worked with Gahn to ascertain in a systemaic manner the of phenomena presented by different minerals when acted on by the blowpipe. He established, according to Griffin, the notion that the blowpipe was an instrument of indispensable utility, and his published work, later translated into English, was regarded as one of the most useful books on practical chemistry extant.

The blowpipes of all of the foregoing blasted air into a flame. Antoine Lavoisier is credited as the first to blow oxygen - of which he was co-discoverer - through a blowpipe to support the combustion of charcoal, in 1782. Others, such as Edward Daniel Clarke, employed hydrogen, and later mixed hydrogen and oxygen in the oxy-hydrogen blowpipe. The vastly increased temperatures, and the volatility of hydrogen-oxygen mixes drove on the development of the so-called gas blowpipe as a tool, and at the same time brought many new materials into reach of the blowpipe as a tool for assay. Robert Hare was a noted exponent of the improved tool. Goldsworthy Gurney, whilst at the Surrey Institute, published in 1823 an account of a new blowpipe so constructed as to enable the operator to produce a flame of great size, power and brilliancy by burning large quantities of the mixed gases with the utmost safety. Gurney went on to employ the principles in his Bude light.

[edit] References

• A Practical Treatise on the Use of the Blowpipe by John Griffin, 1827, from Google Book Search