252 
Proceedings of Royal Society of Edinburgh. [sess. 
Tha Freezing-Point of Aqueous Solutions of Sodium 
Mellitate. ( Preliminary Note.) By W. W. Taylor, M.A., 
B.Sc. ( Communicated by Professor Crum Brown.) 
(Read July 18, 1898.) 
As is well known, the molecular depression of the freezing- 
point of aqueous solutions of electrolytes is greater than 1‘87, van’t 
Hoff’s constant, with which the molecular depressions of non- 
electrolytes have been found to agree extremely well. This is in 
accordance with the dissociation theory; and for binary electro- 
lytes the molecular depression may approximate to P87 x 2, for 
ternary electrolytes to P87x3, etc., hut cannot exceed these 
values. 
Substances such as potassium ferrocyanide, which, according to 
the dissociation theory, might be expected to give values approxi- 
mating to P87 x 4 or 1*87 x 5, have not been found to give mole- 
cular depressions greater than 1 *87 x 3. This has been held to he 
an objection to the dissociation theory. 
At Professor Crum Brown’s suggestion, I have determined the 
freezing-point of aqueous solutions of sodium mellitate in order to 
ascertain whether its molecular depression approximates to the 
theoretical maximum, P87 x 7. 
Sodium mellitate was prepared as follows : — A slight excess of 
mellitic acid was added to a boiling dilute solution of sodium 
carbonate ; after expulsion of the carbonic anhydride, the solution 
was exactly neutralised with pure dilute solution of sodium 
hydrate, using phenolphthalein as indicator. After concentration 
over sulphuric acid, crystals separated out. They were washed and 
twice recrystallised from water. 
Analysis of the air-dried crystals gave numbers corresponding 
to the formula Ha 6 C 12 0 12 , 17H 2 0. 
I. — 0*6137 gm. substance heated to 135° C. lost 0*2350 gm. = 
38*30 per cent. H 2 0. 0*6137 gm. substance gave 0*3332 
gm. Ha 2 S0 4 = 17*61 per cent. Ha. 
