Clerici solution

Clerici solution

Clerici solution is a solution of equal parts of thallium formate (Tl(CHO2)) and thallium malonate (Tl(C3H3O4)) in water. It is a freely flowing, odorless liquid which changes from yellowish to colorless upon decreasing the concentration of the thallium salts. At a density of 4.25 g/cm3 at 20 °C, the saturated Clerici solution is one of the heaviest aqueous solutions known. The solution was invented in 1907 by the Italian chemist Enrico Clerici (1862–1938)[1] and introduced to mineralogy and gemology in 1930s as a valuable liquid, which allowed separating minerals by density with a traditional flotation method. Its advantages include transparency and variable and easily controllable density in the range 1-5 g/cm3.[2][3][4]

The density of Clerici solution is so high that minerals such as spinel, garnet, diamond and corundum can float in the solution.[3] The density of the saturated solution (thallium formate plus thallium malonate in water) increases from 4.25 to 5.0 g/cm3 upon heating from 20 to 90 °C (194 °F).[4] (Note that density of water decreases from 1.0 to 0.96 g/cm3 in the same temperature range.[5]) It can be reduced by diluting the solution with water down to 1 g/cm3. The refractive index shows significant, linear and well reproducible variation with the density; it changes from 1.44 for 2 g/cm3 to 1.70 for 4.28 g/cm3. Thus the density can be easily measured by optical techniques.[2]

The color of the Clerici solution changes significantly upon minor dilution. In particular, at room temperature the concentrated solution with the density of 4.25 g/cm3 is amber-yellow. However, a minor dilution with water to the density of 4.0 g/cm3 makes it as transparent as glass or water (absorption threshold 350 nm).[6]

A common procedure for mineral density measurement using the Clerici solution is as follows: a grain of mineral is placed in a small tank filled with the concentrated solution so that the grain floats on the surface. Then water is added drop-wise until the grain becomes suspended in the liquid. Then the density of the liquid is evaluated either directly by weighing or indirectly through its refractive index, which is measured with the Abbe refractometer.[2]

The drawback of the Clerici solution is its high toxicity and corrosiveness.[2][3]

References

  1. ^ E. Clerici (1907). "Preparazione di liquidi per la separazione dei minerali" (in Italian). Atti della Reale Accademia Nazionale dei Lincei: Memorie della Classe di Scienze Fisiche, Matematiche e Naturale 16: 187. 
  2. ^ a b c d R. H. Jahns (1939). "Clerici solution for the specific gravity determination of small mineral grains". American mineralogist 24: 116. http://www.minsocam.org/ammin/AM24/AM24_116.pdf. 
  3. ^ a b c Peter G. Read (1999). Gemmology. Butterworth-Heinemann. pp. 63–64. ISBN 0750644117. http://books.google.com/books?id=tfXa13uWiRIC&pg=PA63&lpg=PA63. 
  4. ^ a b B. A. Wills, T. Napier-Munn (2006). Wills' mineral processing technology: an introduction to the practical aspects of ore treatment and mineral recovery. Butterworth-Heinemann. p. 247. ISBN 0750644508. http://books.google.co.jp/books?id=tQj4zuW2VL0C&pg=PA247&lpg=PA247. 
  5. ^ Lide, D. R. (Ed.) (1990). CRC Handbook of Chemistry and Physics (70th Edn.). Boca Raton (FL):CRC Press.
  6. ^ A. Kusumegi (1982). "Total Absorption Counter and Viewing Shield by The Use of Heavy Liquidst". Bull. Inst. Chem. Res., Kyoto Univ. 60 (2): 234. hdl:2433/76969. 

Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • clerici solution — kləˈrēchē noun Usage: usually capitalized C Etymology: from the name Clerici : a water solution of thallium malonate and thallium formate used as a liquid of high specific gravity to separate mixtures of solids into their components …   Useful english dictionary

  • Clerici — may refer to: People Carlo Clerici, Swiss bicycle racer Gianfranco Clerici, Italian screenwriter Gianni Clerici, Italian tennis player and commentator Sergio Clerici, Brazilian footballer Other Clerici solution, a solution of thallium formate and …   Wikipedia

  • Clerici-Lösung — Die Clerici Lösung ist eine chemische Lösung aus gleichen Teilen von Thalliumformiat (Tl(CHO2)) und Thalliummalonat (Tl(C3H3O4)) in Wasser. Es ist eine leicht fließende, geruchlose Flüssigkeit, deren Farbe sich mit abnehmender… …   Deutsch Wikipedia

  • раствор клеричи — — [Англо русский геммологический словарь. Красноярск, КрасБерри. 2007.] Тематики геммология и ювелирное производство EN clerici solution …   Справочник технического переводчика

  • education — /ej oo kay sheuhn/, n. 1. the act or process of imparting or acquiring general knowledge, developing the powers of reasoning and judgment, and generally of preparing oneself or others intellectually for mature life. 2. the act or process of… …   Universalium

  • Hawking radiation — is a thermal radiation with a black body spectrum predicted to be emitted by black holes due to quantum effects. It is named after the physicist Stephen Hawking, who provided a theoretical argument for its existence in 1974, and sometimes also… …   Wikipedia

  • MINÉRALOGIE — La minéralogie a pour but l’étude des minéraux, éléments ou composés naturels. Si la notion d’espèce minérale a longtemps varié, depuis quelques décennies les minéralogistes en donnent la définition suivante: un minéral est un solide naturel,… …   Encyclopédie Universelle

  • Lega Nord — Federal Secretary Umberto Bossi Federal President Angelo Alessandri …   Wikipedia

  • Francesco Moser — Pour les articles homonymes, voir Moser. Francesco Moser …   Wikipédia en Français

  • Postglossateurs — Le terme de postglossateurs recouvre l’ensemble des juristes qui, dès le XIIIe siècle, ont renouvelé l’étude du droit, en faisant largement évoluer l’analyse des textes du Corpus Juris Civilis. S’il faudrait préférer le qualificatif de… …   Wikipédia en Français

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”