CHAPTER I. 

 THE CELLS AND THE MANOMETER ATTACHMENTS. 



Having found in the electrolytic method* an excellent means of 

 depositing a considerable number of osmotically active membranes, it 

 was imagined that the principal obstacle in the way of the measure- 

 ment of osmotic pressure had been removed and that certain obvious 

 mechanical difficulties connected with the preparation of a suitable 

 porous vessel and the assembling of the various essential parts of the 

 cell could be readily overcome. It was soon discovered, however, that 

 the problem of preparing a satisfactory background for the membrane, 

 i. e., the porous wall, was vastly more difficult than had been antici- 

 pated.! It was necessary, in fact, to spend a large fraction of the first 

 ten years of the investigation in experimental work in the manufacture 

 of cells. The first four years (1901-1905) were devoted almost exclu- 

 sively to the solution of that problem. At the close of the latter period 

 (1905), only two porous vessels of faultless wall-structure had been pro- 

 duced. These were the cells which were designated in the published 

 records of the work by the letters "A" and "B." 



The first experiments upon the activity of membranes deposited by 

 the electrolytic method were made in such porous vessels as could be 

 found about the laboratory, battery cups, etc. The earliest attempts 

 at quantitative measurement were carried out with a portion of a lot 

 of 100 small porous cups which were manufactured, in accordance 

 with furnished specifications, at a pottery in a neighboring city.j In 

 about one-fourth of these, considerable pressures were developed, but 

 in no case the maximum pressure. All of them leaked, and most of 

 them burst under pressures of less than 20 atmospheres. Only one 

 of them survived a pressure of 30 atmospheres, and that for a short 

 time only. It was not then doubted that the defects which had 

 appeared in the first lot of cells from the pottery could be remedied 

 by the potters themselves, provided the exact causes of the failure of 

 their products could be correctly ascertained and explained to them. 

 Accordingly, with that purpose in view, many thin sections were made 

 of the cells with which quantitative measurements had been attempted, 

 and these were examined microscopically and photographed. It soon 

 appeared that most, if not all, of the conditions which determine the 



*Amer. Chem. Journal, xxvi, 80 (1901); xxix, 173 (1903). 

 ■\Ibid., xxxn, 93 (1904); xxxiv, 1 (1905). 

 \lbid., xxviii, 1 (1902). 



