[Aqualist] : Strange happenings with LOI

[David Wheeler]

Alison,

I can ask someone tomorrow or Tuesday about what might happen to the 
stainless steel at that temperature (Monday is a public holiday here).  
With my very limited knowledge of LOI I have to wonder why you use such 
a high temperature.  You are close to getting thermal decomposition 
rather than combustion.  I used (from memory) about 600-800 degrees and 
that is plenty.  One thing I found is that large samples in a small 
furnace can consume all the oxygen.  It was necessary to open the oven 
door occassionally and let in some fresh air.

For the samples you hve can you manually pick out the flakes under a 
low-power steereo microscope?

cheers,
David

Alison Johnston wrote:

>Hi
>I am a postgrad student trying out LOI for the first time. When my first
>set of samples came out of the Muffle furnace after the second heating (
>at 1050), tiny flakes bounced off  the stainless steel container for the
>crucibles and yes, flakes landed inside my samples.
> 
>Can anyone explain to me why this would be happening? The department
>technicians suggested it was some kind of a reaction in the metal to the
>gas coming from the sediments. ...
> 
>Has anyone experienced this ? Cheers Alison J.  
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>Aqualist mailing list
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>


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David Wheeler

Professional Officer
Geochemistry Laboratory					
School of Earth and Environmental Sciences        			
University of Wollongong,               
Wollongong, 2522, NSW          		
Australia

Phone   02 4221 4586 (office)
	02 4226 5903 (lab)
Fax 	02 4221 4250 

E-mail	dwheeler at uow.edu.au


'These days, if a scientist can't get
 an answer by isotope analysis, he ain't hep'

                       - Isaac Asimov, 1959

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