950 
THE VOYAGE OE H.M.S. CHALLENGER, 
this reduction lias not been carried out. According to Grassi, the increase of density in 
a water of 1'026 at one atmosphere is 0 '00079 per 100 fathoms. From Mr. Buchanans 
observations on the compressibility of distilled water, of sea water, and of glass, it was 
found that sea water was compressed approximately in the ratio 0'0009 for every hundred 
fathoms of depth in sea water, so that if the density of a water at the surface is 1'027, at 
1000 fathoms it is 1'036, at 2000 fathoms 1*045, at 3000 fathoms 1*054, and at 4000 
fathoms it is 1'063. 
In Table I. the density of sea water of average concentration is given for every whole 
centigrade degree from 0° C. to 31° C. It will be observed that its density at 15° *5 6 C. 
Table I. 1 — Density of Standard Sea Water (D 15 . 56 = 1*026) at different Temperatures. 
Tempera- 
ture, 
t° C. 
Density 
at t° C., 
D t . 
<M0 = 
W 
1 ) 15-56 
1 
l)l5'56 
D t ‘ 
Tempera- 
ture, 
f C. 
Density 
at f C., 
D,. 
*(*) = 
D t 
Dl5’56 
ll 
- § 
0 
1-02818 
1-0514 
0-9511 
16 
1-02590 
0-9989 
1-0011 
1 
813 
468 
553 
17 
567 
966 
034 
2 
807 
422 
595 
18 
542 
944 
056 
3 
799 
382 
632 
19 
516 
922 
079 
4 
790 
343 
669 
20 
490 
905 
096 
5 
779 
309 
700 
21 
463 
884 
117 
6 
768 
271 
737 
22 
436 
869 
132 
7 
755 
238 
768 
23 
408 
849 
153 
8 
741 
205 
799 
24 
380 
834 
168 
9 
726 
173 
830 
25 
351 
815 
188 
10 
710 
142 
860 
26 
321 
802 
202 
11 
692 
116 
885 
27 
290 
784 
221 
12 
674 
086 
915 
28 
259 
766 
240 
13 
654 
061 
940 
29 
227 
749 
258 
14 
634 
037 
964 
30 
195 
726 
282 
15 
613 
013 
987 
31 
163 
705 
304 
1 Abridged from the Report on Researches into the Composition of Ocean-Water, Phys. Chem. Chall. Exp., part i. 
p. 70, 1884. 
