40 Scientific Proceedings, Royal Dublin Society. 
ing a small balloon of varnished goldbeaters skin for the mercurial 
valve, and cementing a thermometer in a third opening in the 
plug. The bottle was filled with the balloon collapsed. On being 
brought into the ship the air expanded into the balloon until the 
thermometer in the bottle rose to the temperature of my cabin. 
The baryta was then introduced and well shaken in the bottom 
of the bottle for an hour. Finally, the apparatus was again 
taken out on the floes, and when the baryta solution had frozen 
perfectly hard, the stop-cocks were opened, and a fresh volume of 
air pumped in. On 29th February 19128 of air at a tempera- 
ture—63°5 degrees were examined in this way, and gave a per- 
centage of (0536 of carbonic acid. 
These experiments show amounts of carbonic acid considerably 
higher than what is recognised as the average in the air of open 
places in Britain, and coupling their results with the deficiency 
of oxygen observed in the samples of air brought home by Parry 
and Ross, we may, I think, conclude that Polar air resembles the 
air of high altitudes in possessing a large percentage of carbonic 
acid. 
This conclusion is only what is to be expected when we re- 
member that the two principal agents by which carbonic acid is 
removed from the atmosphere, are both all but absent in high 
latitudes. 
At Floe-bery Beach, North latitude 82°27, where my estima- 
tions were made, there was not a tree or a drop of water within 
a thousand miles. 
This increase of carbonic acid in Polar air is probably too small 
to possess any hygienic significance. In fact, much of the impor- 
tance attached to carbonic acid is due to the circumstance that it 
is more readily estimated than the far more noxious carbonic oxide 
and organic matters with which it is variably associated in atmos- 
pheres vitiated by combustion and respiration. 
In conclusion, I may add a brief note relating to watery. 
vapour in Polar atmosphere. That there was some present even in 
the lowest temperatures was shown by the behaviour of cobalt 
chloride. On 4th of March a paper tinted with the chloride and 
dried to the anhydrous blue, was enclosed in a tube so as to be 
exposed to the air but protected from falling ice crystals. After 
the lapse of 24 hours, during which the temperature varied be- 
