CONCLUSION

In this brief survey there has only been space to touch on some of the milestones in the literature of microchemistry.  There is so much periodical literature available, especially in the three journals devoted to microchemistry: Mikrochemie (1923-1952), Mikrochimica Acta (1953- ) and the Microchemical Journal (1957- ).  There are innumerable booklets of various kinds, such as the British Drug Houses', B.D.H. Reagents for Delicate Analysis and "Spot" Tests (Figure 63), which was the instruction manual that accompanied the B.D.H. Spot Test Kit, from 1932 to just a few years ago.

click image to enlarge (77K) Figure 63. Front cover of one of the numerous editions of the British Drug Houses’ The BDH Spot Test Outfit Handbook.

Over the years, many hundreds of these useful microchemical tests have acquired names—usually the name of the originator, such as Fehling's Solution, or Lugol's iodine, etc.  Compilations of these named reactions were published in book form as long ago as 1916, in Alfred Cohn's Tests and Reagents, Chemical and Microscopical [Cohn, Alfred I. (1903)], and, in 1940, Merck published over 4,510 named reactions in the fifth edition of The Merck Index [Chemical, Clinico-Chemical Reactions, Tests and Reagents (1940);  The tests described in Cohn's book are actually a collection of named reactions published in a series of monthly installments in Merck's Report, from March 1900 to September 1902.  Since its first appearance in serial form (1903), the text matter was further greatly amplified for the 1916 publication.  Cohn (1902) had previously published another useful book on Indicators and Test-Papers (Figure 64).

click image to enlarge (139K) Figure 64. Title page of Cohn’s Indicators and Test-Papers (1902).

Following several articles by others on the use of squaric acid in microchemical tests, the squarates, which are the reaction products between squaric acid and some 40+ ions, have now been optically characterized by Jeffrey Hollifield, and his article, “Characterization of Squaric Acid Precipitates”, published in The Microscope, vol. 51:2 81-103 (2003); it demonstrates that new microchemical tests and procedures are being continuously devised and characterized.

Thus, microchemistry has been a valuable adjunct to microscopy continuously for about 180 years.  It continues into the new millennium, because there will always be microscopical chemists who realize that atoms are atoms, and the way they acted and reacted 180 years ago, is the same way they act and react today, and will continue to do so during the next 180 years.  For as long as there are microscopes and chemicals, there will be microchemistry; what a powerful tool in the armamentarium of the microscopist, and what a fascinating body of literature to support it.