ON THE NATURE OF THE PROCESS OF OSMOSIS AND 
OSMOTIC PRESSURE WITH OBSERVATIONS 
CONCERNING DIALYSIS.* 
LOUIS KAHLENBERG. 
INTRODUCTION. 
A brief but excellent outline of the history of the develop¬ 
ment of our knowledge of osmosis up to 1877 is given by Pfeffer 
in his well-known monograph, “Osmotische Untersuchungen. ’ ’ 
The great importance of osmotic phenomena in physiological 
processes was clearly recognized as early as 1826 by Dutrochet, 
and for half a century later osmotic investigations were con¬ 
ducted very largely, though not exclusively, in the interests of 
physiology. Precipitated membranes were first used by the 
botanist, Moritz Traube, * 1 in 1865, and these were employed by 
Pfeifer in his researches above mentioned. Special interest in 
osmosis has developed since 1887, when by using Pfeifer’s data 
of osmotic pressure measurements van’t Holf sought to show 
that the simple gas laws hold for dilute solutions. Since the 
latter date, so-called semipermeable membranes have been used 
almost exclusively in osmotic investigations. These membranes 
usually consisted of ferrocyanide precipitates of some heavy 
metal, copper ferrocyanide being the favorite precipitate for 
osmotic work, though the ferrocyanides of zinc and nickel w'ere 
occasionally employed, as were also a few other precipitates. 
*This paper will be reprinted in the Journal of Physical Chemistry 
for March, 1906. 
i Centralblatt f. medic. Wissenschaften, 1865. 
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