152 PETTERSSON OCPI EKMAN, SKAGERACKS OCH KATTEGATS HYDROGRAFI. 



The chief contributions to the funcls of the expedition were obtained from Baron 

 Oskar Dickson, from two insurance companies in Gothenburg, viz. »The Gauthiod» and 

 »The Ocean», and from one of the members of the expedition. 



II. 

 Apparatus and methods of iiivestigation. 



Arwidsson's sounding-apparatus. 



Ekman's water-bottle, tigs. 1 & 2, description. 



Pettersson's vacuum-glass-tubes for collecting samples of water, and adapted for 

 gas-analysis. Figs. 2 & 3, 4 & 7 represent the manner in which these tubes are exhausted, 

 filled with water and transported. 



Analytical method for determining the amount of nitrogen and oxygen held in so- 

 lution by the samples of water. Fig. 5 represents the hermetically sealed tube A con- 

 taining the sample, attached by a piece of india-rubber tube to the measuring tube B, 

 which can be tilled entirely with mercury from the reservoir D. By proper regulation of 

 the stopcocks z, y, x and the reservoir D the operator can alternately till the tube B Avith 

 mercury and exhaust it. The air which adheres to the side of the tube and the glass joints 

 is collected in the upper part of B and expelled through the capillary tube z and the funnel t. 

 When a Torricellian vacuum is obtained in B, the upper elongated part of A is broken by 

 pressure on the india-rubber tube and the gases are expelled by boiling the water in A and 

 F. This operation takes half an hour. The volume of the nitrogen and oxygen con- 

 tained in the sample is measured, after the carbonic acid has been absorbed by a portion 

 of alkali, which is admitted into the tube B from the funnel t by opening the stopcock z. 

 During this operation y is shut and B commimicates by means of the stopcock x with 

 the reservoir C, Avhich contains distilled Avater. Finally the oxygen is absorbed by pyro- 

 gallic acid and the remaining volume of pure nitrogen is measured in B. 



For further particulars see the description on page 16 and the paper: »Methode zur 

 volumetrischen Bestimmung der im Wasser gelösten Gase», von O. Pettersson. Berichte 

 d. D. Chem. Gesells. 1889, p. 1434. 



In order to determine the total amount of carbonic acid in seaAvater-it is necessary 

 to analyse a special sample in the manner represented in fig. 6 and described on page 17 

 and in the paper: »Kohlensäurebestimmungsmethode», von O. Pettersson. Berichte d. D. 

 Chem. Ges. 1890, p. 1402. 



Of course some part of the carbonic acid is expelled by the operations above de- 

 scribed, but the total amount cannot be obtained Avithout assiduoush' boiling the sample 

 of Avater Avith hydrochloric or sulphuric acid under greatly reduced pressure. But as the 

 addition of acid Avould interfere with the oxygen-determination, the idea of combining the 

 analysis of all the gaseous matters contained in Avater in one single operation must be 



