538 Proteins 
tration an increase of 5 mm. in the height of the cylindrical mass 
of gelatin will show itself. With a further dilution of NaCl the 
swelling of the gelatin increases very rapidly. 
We now undertook the following series of experiments. We 
perfused 2 gm. of powdered non-bleached gelatin, as in the pre- 
vious experiments, first with 50 cc. M/8 NaCl, and followed this 
with a perfusion with solutions of different neutral salts of in- 
creasing dilution. Table IT gives the results of such a series of 
experiments. 
TABLE II. 
Additional swelling of 2 gm. powdered gelatin previously perfused 
twice with 25 cc. M/8 NaCl and three times with 25 ce. of 
the following solutions. 
wo. | wo) el ots | Saees 
« |= |e bp |S 8s (See 
so} 2 |e (3°) Seal Sa See ee 
1 We ied bo Sie O° 0 225 6. 15 2) 887042 was 54 
INS Brie eee ee O | 2.0) 2:0| 6 112.5/17:5|27 (43° 142 46a earns 
NaNO. 1 ? | 4 | 7 112.5)19.5/29.5/389 148.551 |49 (64 
Na acetate..... 1.5} 1.5) 3 | 6.515 |22 131 (88 |45.d5\440)485%op 
NaGNsee to 3.5)-4. 1°7 112° (21 131° 140° 46" SS ene 
IN agsls) 5 et paee 1 1.5) 2.5} 3.5) 8 -|14 |22.5/80 (39. |47 |55 54 
Nag Oxalate....-:.. 2 |2 | 2 | 3.5) 6.6)14.5\24 |29 |350\s6 Geos 
Naz tartrates... . 2 |2.,2 | 3° 1 6.5)18.5123 132.543 (a6 gen ore 
Naz malate Arata O78 al 1 | 2:5] & 113° 420. 131 - 135° aOee aera 
While the sodium salts with monovalent anion all show the be- 
ginning of additional swelling (¢.e. swelling amounting at least to 
5 mm. increase in height of column) in a dilution of m/64 the 
sodium salts with bivalent anion show this increase in twice this 
dilution; namely, M/128. This would indicate that the metal 
ion alone or prevailingly determines the degree of electrolytic 
dissociation of the gelatin sodium. salt. In other words, the 
gelatin salt formed, when gelatin is treated with NaCl, dissociates 
exclusively or prevailingly in the form gelatin + Na.t The 
anion plays obviously a minor if not a negligible part. 
When we test 3 per cent solutions of such gelatin with alcohol 
we find that. the solution always becomes non-precipitable as 
soon as the swelling becomes marked. 
