SUBJECTS aqua regia

The subsamples were split and sent to different laboratories to be subjected to ten commonly-used and proprietary leach/digestion techniques (a) aqua regia partial digestion method at Acme Analytical Laboratories (b) sodium pyrophosphate and cold hydroxylamine leaches at ALS Chemex (c) enzyme and TerraSol leach methods at Skyline Labs (d) Bioleach and soil gas hydrocarbon analyses at Activation Laboratories (e) Mobile metal ion (MMI) extraction at SGS Minerals (f) 4-acid near-total and sodium peroxide sinter total digestions (under the uses contract) at SGS Minerals and (g) de-ionized water leach at the USGS laboratories. 

Today this research programme raises a sarcastic smile. However, the basic idea behind it, whereby all forms of matter have a common origin and can transmute from one form to another, lines up well with the contemporary notion of a unified theory of matter. In this, science owes something to alchemy. In their untiring quest for gold, the alchemists subjected every known substance to the test of fire and acid aqua regia), thus paving the way to modem chemistry. 

Take the powder, place it on a cupel (testa), and add to it the powder from the residue of the aqua regia and add lead, and subject it to the blast when there is enough lead so that it encloses the powder. Otherwise it would be blown away. Blast it till it blickt (flashes). 

Book Ten deals with the making of the mineral acids used in assaying and in parting operations. Aqua valens is the term which Agricola employs indiscriminately for the acids or mixtures of acids, ignoring the terms aqua fortis or aqua regia then already introduced by previous writers. His description of the materials used for preparation would indicate that a considerable variety of strength and composition of these acids were in use. He describes ten recipes for the materials to be subjected to distillation in the furnace. 

Selenium forms a volatile derivative, piazselenol, which can be subjected to GC analysis (Scheme 5.39). Young and Christian [612] treated selenium with 2,3-diaminonaph-thalene at pH 2.0 and extracted the resulting piazselenol into -hexane. With the use of an ECD, down to 5 10-I° g of selenium could be detected. The procedure, applied to the analysis of selenium in human blood, urine and river water, led to results equivalent to those obtained by neutron activation analysis. Similarly, Nakashima and Toei [613] performed the reaction of selenium (as selenious acid) with 4-chloro-o-phenylenediamine at pH 1 and extracted the derivative into toluene. They reported a detection limit of 0.04 jug. Shimoishi [614] analysed the content of selenium in metallic tellurium by this method. The sample was dissolved in aqua regia, followed by reaction with 4-nitro-o-phenylenediamine and extraction into toluene. Down to 10 ng of selenium could be determined using only a few milligrams of sample. Common ions did not interfere even when present in a large excess. Selenium in marine water was determined after the same derivatization step [615],... 

Subject to this complication, the friction properties of the group are generally similar to those of molybdenum disulphide. The actual coefficients of friction vary with load, speed, temperature and humidity, but some reported figures are shown in Table 14.6. The chemical properties are also similar to those of molybdenum disulphide. They are resistant to attack by water, alkalis and most acids, but are attacked by aqua regia and hot concentrated hydrochloric, nitric or sulphuric acids. The most significant differences are in their electrical conductivity and their oxidation resistance. 

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