L091 
No erystals were obtained with the isomorphous substance sodium 
selenate (Na,SeO,,10H,0), though the solution was highly super- 
saturated containing as much as 100°/, of the dissolved substance 
in excess. The experiments were carried out in the month ot 
February, when the temperature was about 25°. 
In Indian climate, supersaturated solutions of sodium sulphate cannot 
be obtained in the usual way in the summer, since the laboratory 
temperature is about 33° or 34°, ie. above the transition temper- 
ature of Na,SO,, 10H,O; (the transition temperature being 32.383 at 
the International Hydrogen thermometer). Consequently supersatu- 
rated solutions should be prepared at a temperature lower than 32°. 
Rereers (loc. cit.) has proved that sodium nitrate and silver nitrate 
are isodimorphous. Under ordinary conditions, sodium nitrate is 
rhombohedral and has the specifie gravity of 2.265; silver nitrate 
is rhombic and has a specific gravity 4.35. 
Mixed crystals were obtained by Rrregrs, which were rhombo- 
hedral; these contained from O to 52°/, of AgNO, and gave for 
the curve representing the relation between specific volume and 
percentage composition a straight line. If the specific gravity, of 
the AgNO, present in these rhombohedral crystals, is caleulated on 
the suppesition of the additive nature of this property, the value 
obtained is 4.19, a value which is different from that of the ordinary 
rhombie form and hence it points to the existence of a labile rhomb- 
ohedral AgNO, in the mixed crystals. Besides these rhombohedral 
crystals, he obtained also some crystals very rich in AgNO, and 
showing the ordinary rhombic form of AgNO,. Still NaNO, cannot 
release the state of supersaturation of silver nitrate. 
From Kuster’s [Zeit. Phys. Chem. 18, 445 (1894); 17, 357 (1895)| 
work we know that benzoie acid can form solid solutions with 
salicylic acid. Yet either of the acids cannot release the supersaturation 
of the other. 
So Osrwarp’s. view [Ueber Katalyse — Deutsche Naturforscher- 
versammlung zu Hamburg (1901)| that substances which can form 
solid solutions, can release the state of supersaturation of the other, 
is not applicable in the cases of benzoic and salicylic acids. 
The catalysis of the release in supersaturated systems can be 
fairly explained from Osrwarp’s law of successive reactions. Like 
all examples of catalytic reactions in these cases also we notice 
the characteristic disproportion between the quantity of the acting 
substance and the amount of the substance changed by its influence. 
By a particle of dust far below the limit of what is ponderable it 
is possible to cause the relief of supersaturation of an indefinitely 
