SUNIER: Marine fish-ponds of Batavia. 171 
KüCHLER- areometer- temperature in | salinity deduced 
areometer No. reading centigrades therefrom 
4203 23.92 27.0 Sala 
4291 23.05 271.023 34.55) 00 
4294 23.9 27:07 | SA SH MO 
4289 23.9 DT | 34540) G6 
4295 : 23.9 DIR UE 34.55 so 
The first five out of the ten salinities mentioned in the last table but 
one were determined by means of the areometer no. 4295, the last five 
by means of the areometer no. 4289. 
The areometers of KüCHLER and KNUDSEN’s tables (!%) will only serve for 
the direct determination of salinities below + 41'/, °/,). For the sake of 
simplicity I have determined higher salinities ') by diluting one volume of 
fish-pond water with one volume of distilled water, and then doubling the 
salinity found for this mixture. A very few times, when the salinity was 
extremely high, one volume of this mixture had to be diluted once more 
with an equal volume of distilled water. 
By this method of diluting, the salinity obtained was slightly too high, 
for the salinity is the total weight in grammes of all the salts dissolved 
in 1 K.G. of sea-water, not in 1 L.. 
The approximate value of the error we can compute as follows. 
The highest salinity determined by me in this manner amounted to 93.2°/,,. 
The result obtained was a salinity of 23.3°/,, for one volume of pond- 
water mixed with three volumes of distilled water. 
At the moment of diluting and of the areometer reading the tempera- 
ture of both the fish-pond water and the distilled water was circa 28° C.. 
The quantities mixed were therefore: 3 volumes of distilled water of 28° C. 
= 2.98878 weight-units ?); and 1 volume of fish-pond water of 28° C. 
and of a salinity to be provisionally put at 93.2°/,,, which is equal to 
1.06863 weight-units of pond-water °). 
The salinity of this mixture was 23.3 °/90. 
Therefore in 2.98878 + 1.06863 = 4.05741 weight-units of this mixture 
there were present 0.094537 weight-units in salts. These salts were got 
from the 1.06863 weight-units of pond-water; one weight-unit of this 
pond-water therefore contained 0.0885 weight-units of salts; in other 
words, the salinity of this fish-pond water was about 88.5°/,, instead 
IN: 
') In July and September 1918 some of these high salinities were determined by 
our hydrographic assitant Mr. K. M. VAN WEEL by halogen titration. 
2) 1 cM? of distilled water at the temperature of 28° C. weighs 0.996260 grammes. 
3) Calculated by means of the formulae given by KNUDSEN (!6) forS, 6° and ot. 
