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Name: Pat G.
Status: educator
Age: 50s
Location: N/A
Country: N/A
Date: Tuesday, March 18, 2003

Hi, I have gone through you archives and found things on salt crystals. But, my questions is we made salt crystals using salt, bluing and ammonia,what part does the bluing play in the beautiful crystal formation that forms on a sponge shaped like a tree. Second, I understand why the crystal forms in general, salt being cube shaped etc. But why the fine, soft, feathery formations. Ammonia, does this facilitate the formation or become part of the formation. Bluing, what is it really? Couldn't get crystals to form with Epsom salt, at least not through the sponge, why?


There is a bit more to growing colored crystals than is apparent at first glance. Pure substances like salt and Epsom salts have a preferred arrangement of their sub-units. Dyes and other additives interfere with (and sometimes distort ) the preferred arrangement. Thus, what should have been cubic is sometimes shaped differently that what one might observe with the unadulterated material.

Also, what one gets in a crystal growing experiment sometimes depends on the substrate on which the crystals grow. The capillarity of a sponge could lead to results different from that observed if the pure solution was simply allowed to evaporate from a covered petri dish.

Bluing is an organic dye whose structure is very different from the structure of the crystals you are trying to grow.

Ammonia is a gas that is not likely to become incorporated within the crystal. Nevertheless, an ammonia solution could change the pH of the growing medium and thereby have an effect depending on the substance being crystallized.

ProfHoff 617

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