Re: standard formula

On Wed, 26 Dec 2001, Art Kerbs wrote:

> My guess is that adding sugar, gel, dichromate, pigment, to your
> water, will only change the baume not the total volume. The gly,
> ammonia, will change the total amount of your formal. I believe that
> this is the easiest, when I have a batch of 10 oz of water nothing
> changes in till I add gly and ammonia, and my end amount is always
> 10++ oz. 10 or 16 percent of gel only changes the baume not the total
> volume.

It depends on whether an addition dissolves or displaces. The soluble
ingredients such as sugar will dissolve and as you've noted only change
the solutions density. The non-soluble ingredients such as the pigment or
other aqueous solutions add volume by simply taking up space (displacing
the existing volume).

I'm not certain, but I tend to think of gelatin as being semi-soluble.
It does dissociate in the water to some degree, but also still maintains
some of its own structural integrity. It absorbs the water and tends to
swell. To the extent that it doesn't completely dissolve in the water it
has to take up some volume. Pigment paints would also be a semi-soluble
ingredient since some of their initial volume may dissolve, while the
pigment component probably doesn't.

When I worked out the comparison table
<http://rmp.opusis.com/carbon/comparison.html> I decided to normalize the
results based on the volume of water because, as you've noted, many of the
ingredients could be added to the water without increasing the volume.
Nor would soluble impurities in the water affect the relationship. As
such the resulting table would differ from the final volume only by the
relatively small amount of material adding to or displacing the initial
volume of the water. The results would therefore look similar to what
people were already used to seeing, and most people probably have this
much measurement uncertainty in their process anyway.

- Wayde
  (wallen@lug.boulder.co.us)

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Received on Wed Dec 26 14:00:00 2001