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Mineralogy: A history of blowpipe analysis


The beginnings of chemistry may be traced far back in history. The Egyptians experimented with substances such as borax and soda (sodium carbonate) found in the desert. These were only the beginnings of science as it was mixed with superstition. The word alchemy meant the art of the land of Khem (northern Africa), the term in turn derived from an ancient ancestor Kham, or Ham, one of Noah's sons. Eventually however, the superstition of alchemy was dropped around the time of Robert Boyle, one of the new scientists, who in 1661 had published The Sceptical Chymist. From then on the name of the science was permanently changed to a respectable Chemistry.

The blowpipe was developed probably by the first alchemists in the land of Khem, wood being scarce and such a device making a hotter flame using less fuel. This is a tube which, when blown into, introduces a fine jet of air into the flame, increasing its heat at a small point. Directed against a sample, it may, depending upon its position, either be used to oxidize or reduce the sample. The blowpipe was used for centuries by glassblowers and smiths working in silver and gold, and possibly by some miners in crude assays of ores, but after the age of alchemy had died and the age of chemistry had started, it then, partly due to the growth of science and the printing of books, became widely known in its use in mineral analysis.

The earliest records of the use of the blowpipe for analyzing minerals was written by Hooke in 1663 and 1665. In 1670 Erasmus Bartholin wrote concerning the calcination of calcite to lime, by use of a blowpipe. In 1679 Kunckel published a book on glassmaking in which he suggested that the blowpipe would be a useful tool for chemists. During the next two centuries when chemical analysis was being developed, Cronstedt, Gahn, the famous Berzelius, and later Bunsen among others, systematized the use of the blowpipe in the study of minerals, several discovering new elements in the process. Already the old standby reagents such as borax, soda, and salt of phosphorus were being utilized, and procedures were being standardized. Plattner wrote a classic on mineral analysis and its English translations still exist. James Smithson, mineral connoisseur and chemist, who willed his fortune to found the Smithsonian Institution, was expert in use of the blowpipe and could by its use identify many substances.

In those days the science of dry analysis with the blowpipe was explored just about as far as it could go. An example of its use in skilled hands was recounted by O. C. Smith in the second edition of his famous book. The story concerns Professor Gahn in the late 1700s:

"Ekeberg asked Gahn his opinion of the then newly discovered mineral, the oxide of tantalum, and Gahn immediately discovered that it contained tin, although it did not amount to more than 1 per cent" [columbite, probably from America, does often contain an impurity of tin]

Thomson (1831) said that the blowpipe was employed by goldsmiths in soldering, and that Cronstedt and Engestroem first thought of applying this to the examination of minerals. The importance of this instrument then impressed the Swedish chemist Bergman, who wished for a complete examination of the heat of the blowpipe upon all different minerals then known, also by use of the fluxes, three of which were commonly used and are still in use, their different properties being useful with different types of minerals (oxides, sulfides, silicates, etc.). Bergman employed John Gottlieb Gahn, a student of his at Uppsala, to make the experiments, and results were later published in a paper in 1779. Gahn later learned mining, and eventually became an Assessor. Thomson (1831) says that he spent a few days with him at Fahlun, in 1812, and "they were some of the most delightful days that I ever passed in my life. His fund of information was inexhaustible, and was only excelled by the charming simplicity of his manners, and by the benevolence and goodness of heart which beamed in his countenance." However, although Gahn was the most knowledgeable of his age concerning blowpipe analysis of minerals, he was not much of a writer, and Berzelius wrote up his works, giving credit to Gahn, and thus they have been saved for posterity.

Although the field of general chemistry has outgrown the use of the blowpipe, it remains a useful tool in determinative mineralogy. Although part of our mineralogical heritage, and not as precise as is modern equipment, classical methods do remain useful to identify many of the common minerals, and to give clues to some of the uncommon ones. It should be remembered, however, that no one method is perfect for everything, and in the case of blowpipe analysis, it usually cannot be used to distinguish between species containing the same elements, although it may be used to help determine which elements may be present.

However, in these later times the classical methods of determinative mineralogy have been mostly ignored due to sociologic rather than to scientific reasons. In former days mineralogical courses required hands-on experience in both use of the blowpipe and in wet methods of inorganic analysis; in later years the streamlining of education has cut out of the curriculum many of the hands-on methods. This combined with the greater precision of instrumental analysis, which does not require as much experience as do classical methods, has resulted in a sad neglect of the classical methods.

A second reason for the neglect of classical methods is that these have gotten short shrift in textbooks as well as in the classroom. For over twenty years a widely used college text on mineralogy included a revised but inadequate treatment of the subject, in which steps in tests were changed or deleted in an attempt at simplication. Revisers who neither understood it, nor apparently ever tried the results of their revisions, gave the subject an undeservedly poor name when such inadequate treatments discouraged students trying the methods upon known specimens but with resultant failure. Thus many graduates of the last two decades were kept in ignorance of the classical methods.

Another reason for the neglect of classical methods is a lack of historical perspective in mineralogical academia. Due to this ignorance the blowpipe has sometimes been erroneously associated with the age of alchemy, although such a misconception has no evidence to support it. Neither Vannoccio Biringuccio of The Pirotechnia in 1540, nor Lazarus Ercker in his Treatise on Ore and Assaying (circa 1580) mention the blowpipe in connection with either alchemy (neither were alchemists but they lived in its age) nor in connection with assaying, as neither used the blowpipe because its use in assaying had not yet been developed. Even the famous Agricola, who wrote of methods of mining, never mentioned the blowpipe although he discussed assaying in his famous De Re Metallica published in 1556. The blowpipe only became known in assaying and in mineral analysis around 1670, which was a turning point in chemical science when alchemy was dying out and chemistry was developing into a true science. The age of alchemy drew to a close as Hennig Brand, the "last of the alchemists," narrowly beat Boyle to the discovery of phosphorus around 1670. Boyle, however, had in 1661 published The Sceptical Chymist, extolling scientific experimentation and reasoning; from then on alchemy died as an issue and the age of chemistry began. As for the blowpipe, its earliest recorded uses in mineralogy were that of Robert Hooke in 1663, and that of Erasmus Bartholin in 1669 or 1670. Then the blowpipe became very useful in chemistry in the 1700s; it was in the 1800s that blowpipe analysis became fully developed. The blowpipe was instrumental in the discovery of several of the elements, as by such a notable as the famous Berzelius who standardized our chemical system of notation.

More details on the history of blowpipe analysis can be found in O. C. Smith's second edition (1953), and in articles by Lee (1938), Edelstein (1949), Jensen (1986), and Burchard (1994).

As late as 1973, the blowpipe was mentioned as being useful. In M. H. Hey's article "Mineral Analysis and Analysts" (Mineralogical Magazine, March 1973, v.39, p.4-24), Hey said that "Reliance on a single technique is always a mistake; in qualitative analysis it has led to such absurdities as the devising of spot tests for sodium and of crystal micro-tests for manganese, and the neglect of borax-bead and microcosmic-salt bead tests and of blowpipe analysis - a versatile tool in experienced hands." (page 21).

The person desiring to test his own specimens is therefore advised, not to get the most modern texts, but books written by those who were experienced in the subject. An article listing such may be found in the October 1994 issue of Mineral News ("A Review of Some Texts on the Qualitative Chemical Testing of Minerals," v.10, #10, pages 6-7) and in the follow up article in the March 1995 issue of same periodical. There is also a sort of source guide to materials and information, supposedly edited by a Robert Hooke, which is probably a pen-name.

Some references:

- Burchard, Ulrich (1994) "The History and Apparatus of Blowpipe Analysis" Mineralogical Record, v.25, #4, p. 251-277.
- Edelstein, Sidney M. (1949) "An Historic Kit for Blowpipe Analysis" Journal of Chemical Education, v.26, p. 126-131.
- Jensen, William B. (1986) "The Development of Blowpipe Analysis" in J.T. Stock and M.V. Orna (editors), The History and Preservation of Chemical Instrumentation (D. Reidel Pub. Co.), p. 123-149.
- Landauer, J. (1891) Blowpipe Analysis, 2nd edition (reprinted as a 173-page paperback by Lindsay Publications, PO Box 538, Bradley, IL 60915).
- Lee, H. R. (1938) "Mineralogy and the Blowpipe Art" Rocks and Minerals, v.13, #8, p. 227-235.
- Smith, Orsino C. (1953) Identification and Qualitative Chemical Analysis of Minerals. (2nd edition contains Chapter 2 on The Blowpipe and Its Uses, History of Blowpiping on p. 29-31).
- Thomson, Thomas (1831) History of Chemistry, in 2 volumes. Volume II, pages 240-246.

From Martin - April 21, 2002 at 08:58:46
Email: dmartinm[ ]

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