56 ME. CHARLES TOMLINSON ON SUPERSATURATED SALINE SOLUTIONS. 
solution of Glauber’s salt produced a well-shaped lens, from the under convex surface 
of which crystals of the salt radiated rapidly downwards. The flask was heated and 
gradually raised to near the boiling-point, and in cooling the oil formed a number of 
lenticular disks on the surface ; but they produced no separation of the salt, even when 
the flask was shaken. 
Also in the case of volatile oils containing products of oxidation, dust, &c., they may 
form lenses on the surface of the solutions and yet act powerfully as nuclei. If such 
oils he redistilled they still form lenses on the surface, but are no longer nuclear. 
Experiment 4. A dark-coloured oil of bitter almonds formed a lens on the surface of 
a solution of Glauber’s salt, and the lens immediately became bristled with crystals. 
The crystallization was so vigorous that crystals projected above the surface, supporting 
the oil, as it were, on a platform. The oil was distilled into a limpid colourless liquid, 
of which about twenty drops were allowed to fall in succession on the surface of a super- 
saturated solution of Glauber’s salt. The drops coalesced into a beautiful, lustrous 
lens ; but there was no longer any separation of salt. After half an hour or so the lens 
became surrounded with an opaque white disk or halo of benzoic acid. On shaking up 
the solution the oil was diffused in globules through it, and in the course of some days 
became converted into flakes of benzoic acid, which rotated vigorously on the surface of 
chemically clean water, after the manner of camphor. There was no separation of salt 
until the flakes were taken out with a non-catliarized spatula, the contact of which with 
the solution caused it to solidify. 
Newly distilled turpentine formed a lens on the surface of a supersaturated solution 
of Glauber’s salt, and remained so during some days. A drop of the old oil, from 
which the new oil had been distilled, was placed on the surface ; it spread into a film, 
displacing the lens and producing immediate crystallization. 
Experiment 5. Carbonic disulphide and also chloroform formed well-shaped lenses 
on the surface of the supersaturated solution of Glauber’s salt, and slowly evaporated 
without producing crystallization. 
Glycerine and wood-naphtha mixed with the solution, rendering it dull, without sepa- 
rating the salt. Of course, on touching the solutions thus treated with a wire they 
immediately crystallized. 
Experiment 6. A solution of 1^ part of potash-alum and one of water was boiled and 
filtered into a number of flasks. When cold the solutions showed great viscosity. A 
drop of a limpid pale seal-oil spread out into a film on the surface of the alum solution. 
Crystallization set in from every part, and the junction of the planes of crystallization 
gave the surface the appearance of a central point and six radii forming six angles, some 
of 30° and some of 60°. 
Experiment 7. Oleine of tallow, the oleine of fish-oil, and oleic acid from palm-oil 
formed well-shaped lenses on the surface of the alum solution without any separation 
of salt. 
Experiment 8. Benzole, naphtha, oleum anethi, turpentine, and some other liquids 
