Fr. MK - 

 I was actually thinking of using volumes of a simple 'green liquid'.  It is
 interesting that the LD50 for ethanol is 7g/kg so that around ~560 ml of
 pure ethanol.  I just want to show about how big that volume is, so two
 flasks one (10 ml grad cyl) to show that 7ml would kill half a rat and
 another to show the 560 (500 ml grad cyl).

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Demo: show qty for 333gr rat vs. 170# human. 
.33kg : 80 kg => 1:240

ex.	NaCl => 1gr:240gr
	CuSO4 => 0.5gr:120gr

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ref: http://www.ger.ed.ac.uk/hew/tox/table1.html

Table 1. 
Approximate acute LD50 values for some potentially hazardous substances* 

Substance LD50 male(mg/kg body weight) Oral Administration 
Ethanol 7,000 
Sodium chloride 3,000 
Cupric sulphate 1,500 
DDT 100 
Nicotine 60 
Tetrodotoxin 0.02 
Dioxin (TCDD) 0.02 
* Values obtained from the Merck Index, The Sigma-Aldrich Material Safety 
Data Sheets (Sigma-Aldrich Library of Chemical Safety Data), and Casarett 
and Doull's Toxicology. 

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TABLE 2. 
An example of a classification of toxicity based on acute LD50 values 
(Used in EC Directives on Classification, Packaging and Labelling of Chemicals)  
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Category LD50 Orally to Rat (mg/kg body weight) 
Very toxic Less than 25 
Toxic From 25 to 200 
Harmful From 200 to 2000 

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