The doctrine of the nerves. Chapters in the history of neurology

life. He emphatically rejected its supposed cooling action with the same arguments as those used later by Bathurst. It was also Helmont who developed gas-exchange as the true function of respiration: used-up venous blood-its residue-is converted into a "6volatile salt" which is "blown away" by the air breathed in. That it can be so converted is due to a magnale-a celestial "conjugal associate"-a "ferment"-of air filling its pores and spaces; it is thus not the whole substance, but this content of air which is breathed and maintains life. In this Helmont is basically assisted by his discovery of Gas as object-specific exhalations different from such common,-non-specific-volatilia as air and water-vapour (see W. Pagel, William Harvey's biological ideas, Basle and New York, 1967, pp. 79, 194). From the account of Bathurst in the present book, Helmont's view of respiration should well have been significant. Helmont's concern with the colour-change and "thinning-out"-the salty-sulphurous nature-of arterial blood by virtue of pulse and air and the absence of any heat-focus and ebullition in the heart, are also topical. Already in 1647, Hermann Conring had ridiculed Kepler's idea of a fiery light-focus in the heart and reduced the Galenic heart-fire to "something mobile like fire" (mobile igni simile, in: De calido innato major point of interest on the Helmontian side is the emphasis laid in the present book on Boyle's preoccupation with the physical rather than the chemical properties of air-the "spring of the air", its "elater" or elasticity leading to his famous "law". Gas-Helmont's "spirit so far unknown and called by a new name" (Complexionum atque mistion elemental figment., 14) was neglected, if considered at all, or played down as one of various forms of "factitious air", for example by Boyle and by Glisson in his late work On the stomach and gut (1677). It remained to another century to rediscover it and give Helmont his due. It cannot be denied, however, that he was critical against Paracelsus' making even life as a whole dependent upon saltpetre which so much intrigued the Oxford group ("salem e nobis fluidum et intus presentem merum salpetri cagastrum vocat. Adeoque nedum carnes et cruorem sed et totum corpus cum vita esse salpetra et cagastrica persuadere conatur", in: Tria prima Chymicorum, 31). Helmont's Gas and gases thus shared oblivion and resurgence with the nitro-aerial particles and other concepts of Harvey's immediate successors waiting for iatro-mechanics and phlogiston to wane. …