Part III. — Seventh Annual Report 



had been brought to Smith's Bank by the inflow along the bottom of 

 water from further out to sea. Further observation will show whether 

 this surmise is correct or not. In the meantime it is sufficient to insist on 

 the importance of a careful investigation of the coming and going of the 

 chemically distinct waters present in the North Sea in relation to the 

 migration of our food-fishes. 



The present is, however, not the time to discuss these questions with 

 any degree of fulness. This can indeed only be satisfactorily done by a 

 combination of workers, biological and statistical, as well as physical and 

 chemical. 



My endeavour has been to prove that the chemistry as well as the 

 physics of sea water must be allowed an important and direct influence in 

 the conduct of the scientific inquiries connected with the fisheries, and thus 

 to justify the granting of those facilities for research, for which I have to 

 thank the Fishery Board for Scotland. 



In conclusion I have much pleasure in gratefully acknowledging my great 

 indebtedness to Mr J. F. Barbour, Mr J. S. Ford, B.Sc.; Mr Andrew King, 

 Mr W. C. Mackenzie, B.Sc; and Mr T. Murray, for the valuable assistance 

 which they have given me throughout the progress of the mass of ana- 

 lytical work embodied in this report. 



NOTE ON THE CARBONIC ACID AND MICRO-ORGANISMS 

 IN THE AIR AT VARIOUS STATIONS DURING THE 

 CRUISE OF H.M.S. 'JACKAL.' By Charles Hunter 

 Stewart, M.B., B.Sc. 



Though not immediately connected with the special work for which the 

 cruise of H.M.S. 'Jackal' was arranged, it was thought that advantage 

 should be taken as far as possible of the opportunity of determining the 

 condition of the air as regards carbonic acid and micro-organisms. Time 

 did not permit for making such arrangements in the ' Jackal ' previous to 

 her sailing as would have made an investigation of this kind easy, yet with 

 a little pains this difficulty was overcome, and the number of observations, 

 though few in number, were made with as much care as though there had 

 been a laboratory for the purpose. 



Carbonic Acid in the Air. 



A bottle of nearly 10 litres capacity was used, and instead of bellows, 

 advantage was taken of the action of the wind for the purpose of taking 

 the sample. Two holes were bored in the cork of the bottle, through one 

 of which passed a funnel with its stem reaching to the bottom, and through 

 the other a glass tube cut level with the cork inside, and bent at nearly 

 right angles outside. This apparatus having been carefully cleaned and 

 dried inside, was fastened on the forecastle, facing the direction of the 

 wind,, and left there for one hour. Though the weather was sometimes 

 stormy during an experiment, the funnel effectually prevented any spray 

 from passing into the bottle. 



In each sample of air at least two determinations of the amount of carbonic 

 acid were made. The absorbing solution used was a 1 per cent, baryta 

 water made with pure barium hydrate. The acid used for titration was a 

 solution of oxalic acid, such that each 4 cc. were equivalent to 1 cc. 

 carbonic acid of 0° C. and 760 mm. pressure. The oxalic acid, twice 

 recrystallised and air-dried, corresponded to the formula C 2 H 2 0 4 2H 2 0, and 



