Sodium Thiosulfate by Polarized Light Microscopy.


Sodium thiosulfate (Na2S2O3) is a inorganic, white crystalline substance which readily dissolves in water and has a relatively low melting point of around 47°C. It has a number of uses which range from Iodometry, photographic processing, gold extraction and as a neutralizing bleach. In my case we use Sodium thiosulfate in sterile bottles to remove the chlorine from water samples which reduces the effect of chlorine on the microbial samples within the potable water we are testing.

One feature of Sodium thiosulfate, which prompted this article is its strong beneficence, this means it has a range of different refractive indexes depending on the angle of view and as such it is prone to wonderful color emissions.


How it was done:

The principles I followed within this experiment were heavily driven by the work of Ian Bock of the Melbourne Camera Club, who is considered a guru by way of life-size crystal photography.

Sodium Thiosulfate (analytical grade) was placed within a glass soda vial which was heated at around 60°C for about 15 minutes, once the crystals had melted (47°C is the melt temperature) a small volume was transferred onto a pre-labelled microscope slide. A cover-slip was immediately placed over the liquid before it solidified, and, some gentle pressure was applied to ensure there was a thin layer of the thiosulfate. A second slide was also prepared, where the thiosulfate was placed within a concave slide without the cover-slip.

In all cases the slides were left to cool so that the thiosulfate could crystallize and the crystals were then viewed under my typical microscope setup as per the below;


Images (Click to enlarge):

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Benzoic Acid by Polarized Light Microscopy

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