[PASEA] RELATIVE BULK OF WEAK SOLUTIONS 31 
volume at the same temperature of the water in 1 gram of the solution, 
may be determined as follows : 
(1) Mass = Volume X Density. 
For unit mass, volume = 1 -- density. 
(2) Let the amount of salt in 100 grams of the solution be c grams. 
Then the amount of water in 1 gram of solution = 1—c/100 grams ; and 
from the above formula, dividing the mass of the water by its density 
we get the volume of water in 1 gram of solution, /.e., the volume that 
that amount of water would have in the free state. 
In finding these volumes the possible error in the volume of the 
solution is 5 in tbe fifth place, while in the volume of water the error 
is in the sixth place for concentrations less than ‘6 per cent, and is 1 
in the fifth place for greater values of the concentration. 
The following tables give the results found. The headings are 
self-explanatory, the temperature in all cases being 18° C. 
SODIUM SULPHATE. 





Grams of Salt Le Vol. (V) of | Vol. (V’) of 
in 100 grs. Dern a mu 1g. of Sol. |water in 1 g. V—V’ 
of Solution. DÉS 3 (c.c.) of Sol. (c.c.) 
"6338 ‘05915 1°00625 ‘99379 ‘99302 ‘00077 
‘2560 “03935 1:00369 ‘99633 *99580 ~00053 
4187 02959 1:00249 "99752 ‘99718 ‘00034 
*2809 01983 1:00123 ‘99879 “99856 ‘00023 
2593 ‘01830 1°00101 *99899 ‘99877 ‘00022 
‘1727 ‘01218 1:00022 ‘99978 99964 ‘00014 
‘1299 “009157 *99980 1:00020 1:00007 ‘00013 
*08708 | 006136 *99947 1°00052 1°00050 “00002 




It thus appears that all solutions of this salt which have been ex- 
amined have a greater volume than the water which they contain would 
have in the free state. The excess of the volume of one gramme of the 
solution over that of its constituent water, which we may call the ex- 
pansion of the solution, is seen in the above table to be beyond the limit 
of error down to a concentration of about ‘1 per cent. Also there is 
no probability that any solution, however dilute, will exhibit a negative 
expansion or contraction. 
Le 
