280 Argon, a new Constituent of the Atmosphere. [March 20, 



might be expected to end with an element of monatomic molecules, 

 of no valency, i.e., incapable of forming a compound, or if forming one, 

 being an octad ; and it would form a possible transition to potassium, 

 with its monovalence, on the other hand. Such conceptions are, 

 however, of a speculative nature ; yet they may be perhaps excused, 

 if they in any way lead to experiments which tend to throw more 

 light on the anomalies of this curious element. 



In conclusion, it need excite no astonishment that argon is so in- 

 different to reagents. For mercury, although a monatomic element, 

 forms compounds which are by no means stable at a high temperature 

 in the gaseous state ; and attempts to produce compounds of argon 

 may be likened to attempts to cause combination between mercury 

 gas at 800 and other elements. As for the physical condition of 

 argon, that of a gas, we possess no knowledge why carbon, with its 

 low atomic weight, should be a solid, while nitrogen is a gas, except 

 in so far as we ascribe molecular complexity to the former and com- 

 parative molecular simplicity to the latter. Argon, with its com- 

 paratively low density and its molecular simplicity, might well be 

 expected to rank among the gases. And its inertness, which has 

 suggested its name, sufficiently explains why it has not previously 

 been discovered as a constituent of compound bodies. 



We would suggest for this element, assuming provisionally that it 

 is not a mixture, the symbol A. 



We have to record our thanks to Messrs. Gordon, Kellas, and 

 Matthews, who have materially assisted us in the prosecution of this 

 research. 



Addendum by Professor KAMSAY, March 20, 1895. 



Further determinations have been made of the density of argon 

 prepared by means of magnesium. The mean result of six very 

 concordant weighings of different samples, in which every care wan 

 taken in each case to circulate the argon over magnesium for hours 

 after all contraction had ceased, gave the density 19'90. 



The value of R in the gas-equation R = pv/T has been carefully 

 determined for argon, at temperatures determined by means of a 

 thermometer filled with pure hydrogen. I have found that the value 

 of R remains practically constant between 87 and +248; the 

 greatest difference between the extreme values of R amounts to only 

 0*3 per cent. Argon, therefore, behaves as a "perfect" gas, and 

 shows no sign of association on cooling, nor of dissociation on 

 heating. 



The ratio of the specific heat at constant volume to that at con- 

 stant pressure has been reinvestigated ; the mean of four very concord- 

 ant determinations with distinct samples of argon is T645. 



