Avogadro and Dalton: the standing in chemistry of their hypotheses / by Andrew N. Meldrum, D.SC ; with a preface by Francis R. Japp.

  • Andrew Norman Meldrum
Date:
1904
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Licence: In copyright

Credit: Avogadro and Dalton: the standing in chemistry of their hypotheses / by Andrew N. Meldrum, D.SC ; with a preface by Francis R. Japp. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    begun by Gerhardt and Laurent had tended more and more to the cultivation of purely chemical methods. The dis- coveries that we associate with the names of Williamson and Hofmann, for instance, show this. That Avogadro's hypo- thesis, or nothing, is the special basis of Gerhardt and Laurent's system, was what they failed to realise. Regarding it as a makeshift at best, they were willing that it should fall into the background: they put their trust in purely chemical methods. But the school of Ger- hardt and Laurent had no monopoly of purely chemical methods. The truth is, that there never has been devised a system of chemistry, professing a knowledge of the relative size and constitution of molecules, and postulating that purely chemical evidence is to be ignored. Just as all politicians profess patriotism, the chemists of all schools profess chemical methods, and if these methods were self- sufficient, the history of chemistry would abound less than it does with systems. In fact, Cannizzaro's suggestions, and even Gerhardt and Laurent's were long set aside by Kolbe, on the ground of adherence to purely chemical methods. Japp, in the Kekuie Memorial Lecture, has pointed out that until 1870 he [Kolbe] continued to use Gmelin's equivalents instead of our present atomic weights. This arose from his extraordinary power of expressing chemical reactions in terms of chemical constitution, which was unfortunately •coupled with an almost complete inability to realise the force •of arguments drawn from physical laws. Nor did Kolbe express contrition for his adherence to the strictly chemical methods. He afterwards contended that his mistaken adherence to the old equivalents had facilitated his discovery •of the constitution of acids, aldehydes, and ketones, and his prognosis of secondary and tertiary alcohols. ^ Strictly chemical methods are much more available for organic than for inorganic chemistry. There had there- fore been no principle common to both branches of the science, and Dum.as even suggested that there were two sciences of chemistry, organic and inorganic.^ Cannizzaro referred both branches to one principle, and adhered to this
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