198 



Scientific Proceedings, Royal Dublin Society. 



V, 



ii 



Previous to an experiment the three taps (H), (A), and (K) were connected 

 by means of a three-way piece, and the whole apparatus thus exhausted by a 



good filter-pump. The manometer was kept at zero 

 during this process by manipulating the taps (H) 

 and (A). AVhen the apparatus was completely 

 exhausted, oxygen from a gas-holder was allowed to 

 enter through the same connexions until the pressure 

 was again atmospheric. These operations were re- 

 peated three times in succession in order to ensure 

 that no appreciable amount of air would remain in 

 the apparatus. The oxygen used was taken from a 

 cylinder of the gas, and was filtered through a tube 

 containing glass-wool to retain traces of dust, and 

 then passed through a small flask immersed in the 

 thermostat, and containing a little water, in order to 

 saturate the gas with water-vapour at the working 

 temperature (258° C). 



When the apparatus was full of oxygen, the air- 

 free water (which had been prepared by boiling dis- 

 tilled water in an apparatus, previously described, 

 and stored in a bulb of about 250 c.c. capacity over 

 mercury) was allowed to enter. The bulb containing 

 the water w'as attached to the tap (B) and the 

 apparatus exhausted; on opening the tap, the water 

 was displaced ovei" and allowed to rise to the 60 c.c, 

 mark. The oxygen was then allowed to enter until 

 the pressure was atmospheric, when the taps (H) an(|- 

 ( A) were opened simultaneously and closed after about 

 two seconds, thus rendering the pressure in both bulbs 

 exactly the same, and the observations of the mano- 

 meter were then started. The barometer was read 

 at the time of starting an experiment, and the volume 

 of gas absorbed calculated by means of the formula 

 given in a previous paper. 



It was originally intended to make a very complete 

 study of the phenomenon by means of a large number 

 of experiments over a long period of time, but the 

 occupation of the College of Science for purposes 

 other than scientific interfered with this scheme, and 

 finally interrupted the work completely. As it will 

 not be possible to resume the work for some time, the 

 results so far obtained are presented in this paper, 

 since they are of interest in that they clear up some 

 points which were previously in doubt. 



The results of six experiments are given in the 

 table, and the variation of gas-content with time is 

 shown in fig. 2. The points indicated by dots were 

 obtained with an apparatus which was supported 

 rigidly on a slate wall-bracket (such as is used for 

 balances), and braced in every direction with wire 

 stays to eliminate vibration as completely as possible. 

 The points indicated by crosses were obtained with an 

 apparatus supported in the ordinary way by a retort- 

 stand. 



Va 





Fig. 1 



