Secondary classification

A recirculation design (Fig. 10) returns the gas to the classifier through the fan after the fine particles are removed from the gas stream. Such an arrangement requires an excellent soHd/gas separator otherwise the classification becomes less efficient. A perfect soHd/gas separator would be a device having a = 1. If the recirculated gas is entered through a secondary coarse stream classification section, then the classification is not less efficient unless the secondary classification is very iaefficient. 

What will now be proposed is that in addition to its role in ordering the elements, the quantity Z may be used to also affect a secondary classification of the elements, that is, their placement into vertical groups in the sense of the conventional periodic table. In proposing this idea, I make use of what was historically the earliest hint of chemical periodicity, namely, the existence of triads of elements [35]. 

The primary classification of substances made by the alchemists was expressed by saying these substances are rich in the principle sulphur, those contain much of the principle mercury, and this class is marked by the preponderance of the principle salt. The secondary classification of the alchemists was expressed by saying this class is characterised by dryness, that by moisture, another by coldness, and a fourth by hotness the dry substances contain much of the element Earth, the moist substances are rich in the element Water, in the cold substances the element Air preponderates, and the hot substances contain more of the element than of the other elements. 

Nesosilicates are the simplest silicates. They contain isolated or independent Si04 tetrahedra. This group has also been called the orthosilicates. A secondary classification, the nesosubsilicates has been designated by Strunz (1957), who was the originator of the silicate classification. This subclass included species having a second anion or anionic radical. The nesosilicates include the gem minerals zircon, topaz, and the garnet and olivine groups. 

Because of these longer periods, not all of the main block elements were grouped together (e.g., F and Cl were separated from Br and I). Mendeleev therefore had to pursue the secondary classification and the longer periods were cut in half. By partitioning the Mendeleev line before Cu, Ag, and Au, Mendeleev obtained a modified periodic table of chemical elements (Figure 7). 

Detectors are primarily classified with respect to the technique with which they are used, viz. GC detectors, LC detectors and TLC detectors, and this type of classification is generally accepted. There is more debate regarding the secondary classification of detectors and, unfortunately, there are three methods in common use. Each of these methods of classification will be considered in detail. 

One secondary method of classification, and one that is probably the most frequently used, is based on a more rational differentiation and defines a detector as either a bulk property detector or a solute property detector. This secondary classification applies to GC, LC and TLC detectors. 

In addition to the potential divisions mentioned above, a secondary classification may be employed that utilises the divergent electronic natures of the species that attack the starting material, e.g. nucleophilic, electrophilic or free radical. 

Secondary classification Substances having the same first element in their formulae are arranged in alphabetical order of the second element. The secondary classification is not strictly adhered to because account is taken of particular bonding relationships. 

One can conclude at this point that natural, elementary groups (e.g. Li, Na, K,..., Ag) are formed during the secondary classification. Within such a vertical group, the atomic weights of the congeners vary in a stepwise maimer. In the case of the... 

Secondary groups are formed during the secondary classification of the elements ... 

These are examples of ambiguities in what may be termed secondary classification, which is not as unequivocal as primary classification, or the sequential ordering of the elements. In classical chemical terms, secondary classification corresponds to the chemical similarities between the various elements in a group. Meanwhile, in modern terms, secondary classification is explained by recourse to the concept of electronic configurations. Regardless of whether one takes a classical qualitative chemical approach or a more physical approach based on electronic configurations, secondary classification of this type is more tenuous than primary... 

The contemporary author on the periodic system, W.B. Jensen, uses the terms primary and secondary kinship, which should not be confused with the terms primary and secondary classification as used by the present author. A primary kinship as termed by Jensen results from secondary classification according to the terminology used in this book. W.B. Jensen, Computation and Mathematics with Applications, 12B, 487-509,1986. 

A secondary classification of long-range interactions into several distinct types can be helpful. Table 1.1 shows these interactions and whether they are additive in the sense that M123 = i2 + 23 + 31 o shows whether the... 

A function provider (secondary classification), for example Automatic Train Protection System on board of the train ... 

Secondary classification "being of the interface, or a method of its execution ... 

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