44 



C.C. NATURAL HISTORY SOCIETY, 



vain. It is in consequence of this that the discoverers chose the 

 name (Argon - laziness) to express the fact of its extreme chemical 

 inertness. 



There is only one way of satisfactorily recognising Argon, 

 and that is by observing its spectrum. A glass tube, with two 

 platinum wires passing into it, is taken and filled with the gas. 

 The majority of this is afterwards pumped out leaving only a small 

 quantity at a low pressure. The tube is then sealed off and the 

 wires connected to an induction coil. The sparks which pass 

 through the gas raise it to incandescence, so that if placed before 

 a Spectroscope we can see its Spectrum. This consists of a large 

 number of bright lines, chief among which are two in the red, one 

 in the yellow and several in the green and blue. By altering the 

 potential of the current the blue may be made more prominent at 

 the expense of the red, and vice versa. It is this fact that has 

 made several observers conclude that Argon is a mixture of two 

 gases. 



Experiments have been made to see whether plants or animals 

 contain Argon. Some' peas were dried, powdered and treated with 

 certain chemicals. The nitrogen given off was mixed with Oxygen, 

 and on sparking through the mixture no residue was left and hence 

 there was no Argon in the original peas. Some mice were chloro- 

 formed, dried in an oven, powdered up and treated like the peas. 

 Eleven per cent, of Nitrogen was obtained, but no Argon. 



General interest may perhaps stop at this point, but for the 

 chemist the interest only begins. One important question was to 

 determine whether Argon is (i) a compound, (2) a mixture of 

 gases, (3) an allotrope of Nitrogen, or (4) an Element. 



(i) It is not a compound for all methods of decomposition 

 have been applied in vain. 



(2) Diffusion, solution, etc., have failed to separate into it two 

 dissimilar portions. Moreover Olsjewski determined its melting 

 and freezing points, and found them constant, tliis being a most 

 reliable test for the homogenity of a substance. Argon cannot 

 therefore be considered a mixture of gases. 



(3) Its density is 20, and in no single determination has a 

 higher number been obtained. If it were allotropic Nitrogen its 

 density might be 21, but could not be 20. 



Hence experiment points to the elementary nature of Argon. 

 Another question to the chemist is the number of atoms in its 

 molecule, and hence its atomic weight. As Argon forms no com- 



