506 Mr. A. Liversidge on Supersaturated Saline Solutions. [June 20, 



obtained this salt and not the normal with IOH 2 0, although he made what 

 has since been proved to be a mistake in assigning 8H 2 to the modified 

 salt. 



The writer allowed some supersaturated solutions of sodic sulphate to 

 evaporate spontaneously, and after several vaiu attempts at last succeeded 

 in obtaining good crops of such crystals, without admixture of the normal 

 salt, which, of course, is liable to crystallize out also on opening the receiver. 

 The ring of crystals at the top of the solution only were taken. 



Results of determinations of water o f crystallization in crystals of sodic 

 sulphate formed by spontaneous evaporation. 



No. 1. *365 grm. of salt, on drying in water-oven at 100°C, after first 

 well drying the powdered salt with blotting-paper, lost • 1 70 grm. =46*57 

 per cent. OH 2 , =Na 2 SO, 70H 2 . 



No. 2. *172 grm. lost *031 grm.=47'09 per cent., = Na 2 S0 4 , 70H 2 . 

 No, 3. 2-708 grms. lost 1*273 grm.=47*00 per cent., =Na 2 S0 4 , 70H 2 . 

 No. 4. 1-260 grm. lost '605 grm. = 47*00 per cent., =Na 2 S0 4 , 70H 2 . 

 No. 5. 3-936 grms. lost 1*812 grm.=46*69 percent., =Na 2 S0 4 , 70H 2 . 

 No. 6. 3*275 grms. lost 1-520 grm. =46-41 percent., =Na 2 SO,, 70H 2 . 

 c No. 7. 3-326 grms. lost 1*570 gnn.=47'll per cent., =Na 2 S0 4 , 70H 2 . 



Weight. Loss. OH 2 . 



No. grms. grm. per cent. 



1. -365 -170 = 46-57 



2 -172 -081 = 47-09 



3 2-708 1-273 == 47*00 



4. 1-260 -605 = 47-00 



5. ........ 3-936 1-812 = 46*69 



6 3-275 1-520 = 46*41 



7 3*326 1-570 = 47*11 



I trust that by the above-mentioned results I have clearly proved the 

 following facts with respect to supersaturated solutions of sodic sulphate : — 



1. That liquids and solids, such as alcohol, quicklime, &c, do not de- 

 termine crystallization by removing water. 



2. That thin films, when sufficient precautions are taken to guard against 

 the entrance of nuclei, do not act as nuclei. 



3. That chemically clean crystals of the normal salt (Na 2 S0 4 , 10H 2 O) 

 do act as nuclei and are most powerful. 



c 4 . That crystals of the normal salt are not produced in supersaturated 

 solutions of sodic sulphate on allowing it to evaporate spontaneously, but 

 that crystals of the modified (and known inactive) salt are. 



In conclusion I may perhaps be permitted to state that the above series 

 of experiments have extended over a period of three years, less a few 

 months, and that most of them have been repeated a countless number of 



