ON THE THEORY OF SOLUTION. 325 
most. Instead, then, of these experiments of Mr. Pickering finally dis- 
proving “all existing physical [sic!] theories of solution,” and in especial 
“the theory of osmotic pressure,” they afford the most striking proof of 
the applicability of van ’t Hoff’s theory and the hypothesis of electrolytic 
dissociation to dilute solutions, with which alone these theories have 
hitherto been concerned.’ 
; es 
Freezing-point ea eat T0090 
H,SO, percent} Sp. gr. Gr.-equiv. | i=1+2a j BN i 
Obs., Obs., | Cale. |Obs.,-calc.|Obs.,-cale. 
° ° 
3'993 1:0278 *8376 2:036 —1'61 _ —162 —10 —_ 
3°967 1°0274 "8324 2°036 1°58 -- 161 —30 —_ 
3°492 10243 ‘7300 2°042 1:37 _ 142 —50 —_— 
3°008 1:0210 6267 2°051 119 _ 1:22 —30 — 
2806 1:0193 5835 2-058 1:10 _ 114 —40 _ 
2°496 10174 “5182 2-064 “981 _— 1016 —35 —_ 
1°996 1:0140 *4130 2°082 ‘788 —_ 817 —29 — 
1:785 10126 +3688 2-088 705 699 “731 —26 —32 
17596 10112 *3293 2-094 633 627 “655 —22 —28 
1°398 10100 "2882 2-102 558 “550 575 -17 —25 
1-212 1:0087 "2496 2-112 “484 480 501 -17 —21 
1:024 1:0073 +2058 2°126 “417 412 “416 +1 —4 
+8188 1:0059 1681 2-136 “334 “332 “333 +1 -1 
7138 10051 “1464 27146 297 294 298 -1 —4 
“6145 1:0044 “1260 2°156 “255 "254 258 -3 —4 
“5146 10037 1054 2°168 "219 “217 217 +2 0 
“4061 1:0029 08312 2-210 178 ‘177 175 +3 +2 
"3562 10025 07288 2236 160 "155 155 +5 0 
3063 1:v022 "06264 2°272 138 137 135 +3 +2 
*2594 10019 “05281 2°304 115 ‘116 116 —1 0 
“2056 10015 "04203 2°352 095 “093 “094 +1 -1 
1539 1°0011 03144 2-406 “067 072 072 —5 0 
1401 1-0010 02861 2-422 +062 067 066 —4 +1 
1012 1:0007 02067 2-476 052 049 049 +3 0 
‘0771 10005 *01574 2544 038 035 038 0 -3 
“0519 1:0003 “01060 2-594 026 “028 026 0 +2 
“0264 1:0001 00539 2°702 016 014 “014 +2 0 
Sum. +7 -—10 
Dr. WaLKER drew attention to the fact that in almost all the combina- 
tions of solvent and dissolved substance tabulated electrolytic dissociation 
played a great part, entirely neglected by Mr. Pickering. The compari- 
son of observed with ‘ theoretical’ values was thus open to the same ob- 
jection as Dr. Arrhenius urged in the case of dilute solutions of sulphuric 
acid, and so the great discrepancies found in the tables were from this 
cause alone rendered illusory. 
Professor Ramsay suggested that it might well be the case that 
complex molecular aggregates were capable of existence alongside of 
dissociated molecules where ions are present. In the case of solutions of 
sulphuric acid, for example, it is by no means inconceivable that aggre- 
gates of several molecules of sulphuric acid (H,SO,),, or of compounds 
of acid and water, such as H,SO,.2H,O, &c., might exist along with 
the ions of dissociated sulphuric acid, 2H and SO,, or more probably 
‘Hand HSO,. The abnormal results in the freezing-points of solutions 
of sulphuric acid observed by Mr. Pickering might well be due to some 
such cause. 
Dr, ArmstronG, after remarking that thus far the physical aspects of 
the main problem under discussion—the constitution of solutions which 
conducted electrolytically—had alone been dwelt on, said that it would 
