[alt-photo] Re: Math mystery

Jacques Kevers jacqueskv at gmail.com
Thu Feb 28 22:30:30 GMT 2013


Luciano & Brian: Both your calculations are going exactly the same way as
my reasonning, and end up with 81ml of 37% solution and 919ml of water,
where the quote from the article I mentioned was speaking of 25ml.
(Luciano, following your calculation: 37/3= 12.33L, with 1L of 37%. Thus in
1L of the new dilution, I have 1000ml/12.33= 81.1ml of the original
product..)
I think that the explanation of Kees answers this mystery: if the "37%
formaldehyde" is in fact considered as full strength/100%, then of course
the 25ml are very near to a 3% solution in a total volume of 1000ml. The
"mystery" came from my ignorance of this equivalence.
Thanks, all!
And yes, Kees, I agree that formalin is nasty stuff...
Best,
Jacques

2013/2/28 Kees Brandenburg <workshops at polychrome.nl>

>
>
> > So, when using a 37% solution of formalin, I would think that you have to
> > use around 80ml of the formalin solution...
>
> Jacques,
>
> Formalin is a 37% solution of formaldehyde gas in water. This is
> considered as full strenght (= 100%) formalin. If a recipe asks for 25ml
> undiluted formalin in 1 liter water this is  a 2,5%  formalin solution.
> Your correction by adding 80ml instead of 25 ml to compensate for the 37%
> formaldehyde solution in formalin is wrong. You end up with a too strong
> mix!
>
> Anyway I should try to avoid formalin alltogether.
>
> Kees
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