1899-1900.] Mr J. J. Manley on Examination of Sea- Water. 37 
beam Oertling balance and a recently standardised box of weights. 
Table A shows the values obtained for the different weighings in 
the two series. 
Table A. 
Series. 
Weight 
Weight 
of tube + 
Weight 
of 
Water required to fill tube at 24 
°C. 
of tube. 
distilled 
water. 
distilled 
water. 
l v . 
2 V . 
3 V . 
4 V . 
5 V . 
I. 
16-8912 
64-7332 
47-8420 
49*0754 
49-0613 
49-0561 
49-0582 
49-0738 
I s 
II. 
16-8908 
64-7302 
47'8394 
49-0770 
49-0607 
49-0585 
49-0630 
49-0752 
r a 
J & 
If W be the weight of a certain volume of sea-water which fills 
the Sprengel tube at 24° C. and w : . the weight of the same volume 
of distilled water, also at 24° C., then W/w : expresses the relative 
density at the temperature named. The values shown in Table B. 
were obtained in this manner. 
Table B. 
Sample of Water. 
Series I. 
Series II. 
Means. 
1-02578 
1-02587 
1-02582 
2 V 
49 
53 
51 
3 V 
38 
48 
43 
4 V 
42 
58 
50 
5^ 
75 
83 
79 
The Optical Measurements. 
The refractive indices of the five samples of water, together 
with that of recently re-distilled water, were next determined with 
the aid of the above-mentioned large spectrometer and hollow 
quartz prism. Two series of measurements were made at the 
ordinary temperature of the room, on two different days. The 
bottles containing the waters to be examined were placed upon a 
shelf, close to the spectrometer, the day before any measurements 
were proceeded with ; on the day of examination the water would 
