348 Proceedings of Royal Society of Edinburgh. [sess- 
the sea-water, then filled and hermetically sealed ; it was then- 
packed and kept in complete darkness until its contents were- 
examined in the laboratory. 
It should here he stated that when this research was commenced 
I was quite unaware that Professor Knudsen had published in the 
Berichte der Kommission zur ivissenschaftlichen Untersuchung 
der ddnischen Fahrwasser (Copenhagen, 1900) the results of 
some very interesting experiments conducted by him, partly upon 
the open sea and partly in the laboratory. An abstract of his 
paper by Schott appeared in the Annalen der Hydrographie 
for March 1901, and to this Mr H. N. Dickson very kindly drew 
my attention. Knud sen’s experiments, like my own, had for their 
object the determination of the relationship between the total 
salinity and the electric conductivity of different samples of sea- 
water. The apparatus and methods adopted by Knudsen differ, 
however, in some essentials] from those chosen by myself; our 
conclusions also are somewhat at variance. Consequently, in view 
of the importance of the subject, it is hoped that a short account 
of my methods and results may not prove uninteresting. 
The work has been done in the Daubeny Laboratory of 
Magdalen College, Oxford, at intervals during the years 1901-2. 
I desire to express my indebtedness to Mr R. T. Glinther and 
Mr H. Hilton, Fellows of Magdalen College, for the very valuable 
assistance which they have given me during the course of this 
research • and also to the Government Grant Committee of the 
Royal Society, for the continued loan of certain pieces of 
apparatus. 
Preparation of the Samples of Water for Examination. 
In addition to the natural sea-water, four others were prepared 
from portions of it ; two had a smaller and two a greater total 
salinity than that of the natural sea-water. The two weaker 
samples were respectively prepared by adding 10 c.c. of distilled 
water to 190 c.c. of the sea-water, and 5 c.c. of distilled water to 
195 c.c. of the sea-water. The two samples having a greater total 
salinity were obtained by concentrating separate quantities in a 
porcelain dish over a water bath. In all, five samples of water 
