405 
Chemistry. — “Supersaturation and release of supersaturation 
By Devendra Nath Bhattaoharyya and Nighatan Dhar. 
(Aangeboden door de Heeren Ernst Gohen en F. M. Jaeger). 
The older literature on supersaturation, chietly works of Gay 
Lussac 1 ), Schaveigger 2 ), Ziz 3 ), Thomson 4 ), Ogden 5 ), and others, 
abounds with evidences showing that the phenoraenon is ratlier 
eomraon. 
Bnt after that, the general idea of the chemists was that only 
few snbstances could form supersaturated Solutions. 
But now a days. chemists have recognised again that the pheno- 
rnenon is coramon. Tiras Mendeléeff [Principles of Chemistry, English 
translation (1905), p. 93] States that salts which separate out with 
water of crystallisation and form sei^eral crystallohydrates yield 
supersaturated Solutions with the greatest ease, and the phenoraenon 
is much more coramon than was previously imagined. Ostavald 
lias studied this ease very thoroughly and is of opinion that this is 
very comnion. Tütton also mentions in his book, “Crystals” (p. 238) 
that supersaturation is a phenoraenon of frequent occurrence. 
But the reminiscenoe of the old idea is still unconsciously present 
in the popular mind. For demonstration experiments, sodium acetate, 
or sodium sulphate, or sodium thiosulphate is invariably taken. Also 
the idea is predominant that only hydrated salts eau be easily super- 
saturated. Sodium chlorate is cited as a solitary example of an 
anhydrous salt capable of forming supersaturated solution. Again, 
no systematic Avork of a quantitative character is available in this 
direction. These led to the present investigation of showing the 
general tendency of almost all substances of forming supersaturated 
Solutions. 
At first qualitative experiments were done with varied substances. 
These were all performed in well cleaned, steamed test tubes fitted 
with similarly operated corks. The solution is boiled for a few 
minutes till all the particles of the substance on the side of the test 
q Ann. Ghim. 87, 225; Schw. 9 , 70; Ann. Ghim. Pliys. 11 , 301. 
2 ) Schw. 9 , 79. 
*) Schw. 15 , 160. 
Ann. Phil. 19 , 169. 
B ) N. Ed. Phil. J. 13 , 809 
