On Thu, 29 Mar 2001, David Grehan wrote:

> Here is a simple test ;
> Add  few drops of the fluid to 1 ml of your reticulin silver solution.
> If it turns white the fluid is saline.
> If it turns black you have got formalin .

Excellent! You can also use Schiff's reagent in exactly the
same way (excess of reagent over test solution). It immediately
goes magenta with formalin. The excess of Schiff is desirable 
because dilution, especially if this goes with neutralization 
(buffered saline), will cause slow development of a pink colour.

It is possible to sniff nasty chemicals carefully, by a gradual
approach with 1 or 2 fingers making rapid wafting movements
between the jar and the nose, while pulling air in slowly not
by inhaling but by lowering the floor of the mouth with the
glottis closed. This is probably something of a lost art, but
it does teach one to recognize low concentrations of noxious
vapours. If the air in your lab contains some chlorine, sulphur
dioxide, formaldehyde, ammonia or whatever, it's useful to be
able to identify it so that you can replace a bottle cap, wash
out the sink, phone the undertaker, or do whatever else is needed.  
  
----------------------------------------
John A. Kiernan
Department of Anatomy & Cell Biology
The University of Western Ontario
London,  Canada   N6A 5C1
   kiernan@uwo.ca
   http://publish.uwo.ca/~jkiernan