Re: Chrome alum

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From: Katharine Thayer (kthayer@pacifier.com)
Date: 12/10/01-06:04:01 PM Z


Judy Seigel wrote:
>
> I was pointing to the fact that he changes terms midstream. That is, under
> the chrome alum he refers to white alum, presumably the potassium alum,
> but under potassium alum he never says "this is the white alum", only
> referring to it as "common" or colorless, so that a person could well
> think there was some THIRD kind of alum, not in the index.
>
> This kind of thing does happen, but not good manual writing.

It looks to me Scopick has been getting rather a bum rap in this whole
discussion.

In the text, he states clearly that he prefers formaldehyde, (formalin,
if you will) and he gives instructions only for hardening with
formaldehyde. He mentions the alums only in passing, referring anyone
interested in learning about hardening with alums to another source.
It's only in the chemical appendix that he gives the (correct) formulas
for the alums, and makes the (apparently well-founded) statement that
chrome alum hardens better than the ordinary white alum. I can find
nowhere that he mistakenly says that either of the alums is sold as a
dihydrate. The only charge that sticks is that he apparently
overestimates the intelligence of his readers when he assumes that a
person could deduce that "ordinary white" alum is probably the same as
"common alum." But given how peripheral all this is to his text, I have
a hard time thinking it's worth getting all worked up over.

Katharine Thayer


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