Liebig Justus. Professor Liebig's Complete Works on Chemistry

Philadelphia: T.B. Peterson, 1850. — 308 p.The present little work contains a series of experiments the object of which is to ascertain the law according to which the mixture of two liquids, separated by a membrane, takes place. The reader will, I trust, perceive in these researches an effort to attain, experimentally, to a more exact expression of the conditions under which the apparatus of the circulation acquires all the properties of an apparatus of absorption. In the course of this investigation, the more intimate study of the phenomena of Endosmosis impressed on me the conviction that, in the organism of many classes of animals, causes of the motion of the juices were in operation, far more powerful than that to which the name of Endosmosis has been given. The passage of the digested food through the membranes of the intestinal canal, and its entrance into the blood; the passage of the nutrient fluid outwards from the blood vessels, and its motion towards the parts where its constituents acquire vital properties, — these two fundamental phenomena of organic life cannot be explained by a simple law of mixture. The Experiments described in the following pages will, perhaps, be found to justify the conviction that these organic movements depend on the transpiration and on the atmospheric pressure. The importance of the transpiration for the normal vital process has, indeed, been acknowledged by physicians ever since Medicine had an existence; but the law of the dependence of the state of health on the quality of the atmosphere, on its barometric pressure, and its hygrometric condition, has been hitherto but little investigated. By the researches contained in my examination of the constituents of the juice of flesh, as well as by those described in the present work, the completion of the second part of my Animal Chemistry has been delayed; but I did not consider myself justified in continuing that work until I had, examined the questions suggested by, and connected with those researches.