Thus the groupings J_C C - - C C - >N CH 3 and - C C C N exist in the molecule, and the alkaloid is to be represented as a-pyridyl-N-methyl-pyrollidine.
Many genera and families are separated by purely artificial characters, mere shelfand-bottle groupings devised for the convenience of the museum curator and the collector.
In the course of the 19th century the idea that the different elements are constituted by different groupings or condensations of one primal matter - a speculation which, if proved to be well grounded, would imply the possibility of changing one element into another - found favour with more than one responsible chemist; but experimental research failed to yield any evidence that was generally regarded as offering any support to this hypothesis.
We now proceed to discuss the types of aliphatic compounds; then, the characteristic groupings having been established, an epitome of their derivatives will be given.
Compounds containing these groupings are, however, rarely observed (see Chloral), and it is generally found that when compounds of these types are expected, the elements of water are split off, and the typical groupings are reduced to - CH :0 and >C: 0.
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