ARGON, A NEW CONSTITUENT OF THE ATMOSPIIEUE. 23 



copper; but instead of thus c()iiiplic;itiii<,' tlie apparatus, a waler-injcctoi' was made 

 use of to induce eireulatiou. Ilei-e also it is unnecessui'y to enter into details. Foi-, 

 though the plan woi'ked well, and allliougli about 120 litres of " atniospheiic " 

 nitrogen wei-e absoibed, the yield of argon was not huge, about COO cubic centi- 

 metres having been collected. This loss was subsequently discovei'ed to be due 

 partially at least to the I'elatively high solubility of ai'goii in water. In order to 

 pro[)el the gas over magnesium, through a long combustion-tube packed with turn- 

 ings, a considei'able water-pressure, involving a large flow of watei', was necessary. 

 The gas was bi'ought into intimate contact with this water, and presuming that 

 several thousand liti'es of v.ater ran through the injector, it is obvious that a not 

 inconsiderable amount of ai'gon must have dissolved. Its pi'opoition was increasing 

 at each circulation, and consequently its partial pressure also increased. Hence, 

 towards the end of the operation, at least, thei'e is every reason to believe that a 

 serious loss had occurred. 



It was next attempted to pass "atmospheric nitrogen " fi'om a gas-holder first 

 through a combustion-tube of the usual length packed with metallic copper re- 

 duced from the oxide ; then through a small U-tube containing a little water, 

 which was intended as an index of the I'ate of flow ; the gas was then dried by 

 passage through tubes filled with soda-lime and phosphoric anhydride, and it next 

 passed through a long iron tube (gas-[)i[)e) packed with magnesium tui'nings, and 

 heated to briizht i-edness in a second combustion-fai'iiace. After the ii'ou tube 

 followed a second small U-tube containing water, intended to indicate the rate at 

 which the ai'gon escaped into a small gas-holder placed to receive it. The niti'ogen 

 was absorbed rajDidly, and argon entered the small gas-holder. But there was i-eason 

 to suspect that the iron tube is permeable by argon at a red heat. The first tube- 

 full allowed very little argon to pass. After it had been i-emoved and replaced by 

 a second, the same thiua; was noticed. The first tube was difiicult to clean ; the 

 niti'ide of magnesium forms a cake on the interior of the tube, and it was very 

 difficult to i-emove it; moreover, this rendered the filling of the tube troublesome, 

 inasmuch as its interior was so rough that the magnesium turnings could only 

 with difficulty be forced down. However, the permeability to argon, if such be 

 the case, appeared to have decreased. Tlie iron tube was coated internally with a 

 skin of magnesium nitride, which ap[)eared to diminish its permeability to argon. 

 Aftei' all the magnesium in the tube had been converted into nitride (and this was 

 easily known, because a bi-ight glow proceeded gradually from one end of the tube 

 to the other), the argon remaining in the iron tube was " washed " t)ut by a cur- 

 rent of nitrogen ; so that, after a number of operations, the small gas-holder con- 

 tained a mixture of argon with a considei'able quantity of nitrogen. 



