Blowpipe (tool)
The blowpipe is a metal tube with a small, laterally attached nozzle and a mouthpiece. It is for examining minerals - especially metals - and used in inorganic qualitative analysis as a so-called preliminary test. Through the die, air is blown into a flame, and so the sample is heated to very high temperature. Thus, electrons are thermally excited and a typical flame color is produced. The color of the flame, the Oxidbeschläge and the type of melting products is preliminary evidence on the composition of the sample. The flame source used in the simplest case, a candle or an oil lamp ( for example, turpentine oil, rapeseed oil ). Better results are obtained with a laboratory - alcohol burner or coal gas in the Bunsen burner. The most reliable results are obtained with a propane torch.
Method
In a depression on a piece of charcoal (ideally Linde charcoal), a mixture of soda and powdered substance under investigation is stirred. If the blowpipe is placed in the central, luminous flame and strong, but equally blown through the mouthpiece you get the so -called oxidizing flame. If the blowpipe set on the edge of the flame and blown only with moderate air flow so that no bright luminous flame is produced, it generates the reducing flame. The soda - sample mixture is usually first melted and then oxidizing reduced. Depending on the sample composition is obtained small molten balls, metallic tinsel or under oxidizing conditions in the colder areas of the charcoal Oxidbeschläge. Based on the coloration of the Oxidbeschläge and the properties of the melt products ( ferromagnetism, ductility or brittleness ) first conclusions on the nature of the sample composition can be drawn. If necessary, the procedure is repeatedly, e.g. repeated with the addition of cobalt nitrate solution, and evaluated the color and the properties of the melt products.
A more accurate determination, the " pearls sample". The addition of borax or phosphates done melting of the sample substance, some metals stain the borax or microcosmic salt beads characteristic. Another possibility of the laboratory is to evaluate the flame coloration of the sample in a platinum loop. The flame color can be best assessed using a Handspektroskops.
History
This method is called Lötrohrprobierkunst and is a method of general Assaying. The blowpipe was first used in 1738 according to the records of Jöns Jakob Berzelius by the Swedish mining engineer Anton von Swab in order to deflect from a flame by means of the additional " blast " a hot jet and thus to examine minerals.
A stronghold of the Lötrohrprobierkunst and mineral analysis was the Freiberg in the 19th Century. Here was especially Karl Friedrich Plattner (1800-1858) active. He wrote the book entitled Probirkunst with the blowpipe, ... ( 1835). It has been repeatedly applied and Revised:. From 1842 to 1856 he was professor of metallurgy and Lötrohrprobierkunst. However, the first paper on Lötrohrprobierkunde comes from Gustav von Engeström ( An essay towards a system of mineralogy ) in English from 1770, in which he described the handling of the blow pipe for experiences of the Swedish Mountain Master Axel Frederic CRONSTEDT. A German translation ( Mr. Gustav von Enge 's current description of a mineralogical bags Laboratory and in particular the benefits of the bubble tube in mineralogy ) was published by AF Rose in 1782 in Greifswald.
Justus von Liebig developed the Lötrohrprobe as a preliminary test for the qualitative analysis. In the 19th century, this way of working was very common among chemists. So Liebig calls among the three characteristics that identify the chemist, the " tips of the lips when kissing " as an effect of working with the blowpipe.