Adsorption and Hæmoglobin

Abstract

IN his letter published in NATURE of May 19, Sir William Bayliss suggests that two cases of adsorption do not come within the definition of adsorption to which I directed attention in NATURE of April 14. These are the cases when two or more substances are adsorbed upon a surface, and when a substance is adsorbed to a thickness of several molecules. Both these cases were intended by me to be included, and I think reasonably so, with the definition that it is a case of adsorption, if the substance is taken up uniformly over the whole surface; uniformly, that is, when the scale of measurement is large compared with individual molecules. This sense of uniformity is well understood in the theory of gases, where a mixture of gases or a single gas may be said to fill space uniformly, with equal correctness. I had no intention of limiting the definition to layers only one molecule thick; indeed perhaps I may be permitted, as it is suggested that I accept Langmuir's views, to point out that the theory employed by Langmuir does not seem to me necessarily to postulate that adsorbed layers are always one molecule thick. Such a proposition could only be established by estimating the amount adsorbed on unit area and calculating the thickness of the layer in terms of known data as to the size of the molecules in every case of adsorption; it does seem to be established by the beautiful experimental work of Langmuir in many cases, but is not, I think, claimed by him to be an invariable law governing adsorption.