42 
THE VOYAGE OF H.M.S. CHALLENGER. 
!\ -is. ami that its precision consequently must be presumed to be rather above the 
average. 
Column IX. — This column, as is seen, is headed “ B. ; x 1 — X- The symbol x* 
-t u.. 1 - 1'. r tin amount of chlorine per kilogramme, as calculated from Mr. Buchanan’s deter- 
minat ion of the specific gravity by means of the formula 4 S, — 4 W,= a + bt + ct 2 , which is 
. xpUim d on p. 5S as summing up a series of standard determinations of my own. A 
print- 1 list of Mr. Buchanan’s specific gravities was placed in my hands b} r the Editor of 
tin Challenger Reports. This list, in addition to the values 4 S, found directly at t° C., 
gave also the specific gravities at 15 0- 56 C., reduced, as I am informed by Mr. Buchanan, 
from the former by means of Hubbard’s Tables of the thermic expansion of “ sea-water.” 
In my original draft for this memoir I gave the values x 1 as deduced from these latter values 
by my formula. But when I subsequently came to criticise Hubbard’s results in the 
lijht of my own experiments, and of those of Thorpe and Riickcr and of Ekman, I found 
• II tbbacdfe Table is infected with inaccuracies,* which I saw I had no right to 
char.:-- against Mr. Buchanan's determinations. I accordingly re-calculated all my values 
of x from Buchanan’s directly determined specific gravities by means of my formula, and 
it is these re-calculated values, or rather their excesses over the value x> which are now 
before the reader. 
Column X. gives the “ Laboratory Number” by which the sample was known in my 
laboratory. 
* Vide infra. 
