226 48 



glass Uibings shown in Fig. 11, to the glass bulb g, whence it falls through the 

 fall-tube, and in this way comes back to the vessel N, where it started. The 

 T-tube T is inserted, so that the mercury is not drawn into the tube r when its 

 surface in N is lower than tlie T-tube. For this reason, the porous plug C is 

 never exposed to the air. 



III. 

 On the results. 



In the accompanying table of analyses. Table I, the name and number of the 

 springs, in the first column, refers to the designation given in the description of 

 the surroundings of the springs, (Part I), where particulars of their position and 

 appearance will also be found. In the column headed "Calculated Boiling Point', 

 is given the boiling point of distilled water calculated from the atmospheric pres- 

 sure at thespring at the time of investigation. 



The integral parts of the spring gas are expressed in their percentage to the 

 volume of the gas; thus, the statement that the sample of the spring gas "Krafla 

 No. 1" contains 12.6 "/o sulphuretted hydrogen, signifies that 100 ccm. of the spring 

 gas in question contains 12.6 ccm. of sulphuretted hydrogen. The volumes are 

 reduced to 760mm. pressure and Centigrade. Column "R" gives the percentage 

 of the volume of the gas not absorbed by the agents usually employed in analysing 

 gas, i. e. nitrogen, plus rare, inactive gases. 



The radium emanation contained in 1 ccm. of the spring gas is expressed in 

 the before-mentioned unit, (cf. p. 30), and is to be found in columns Ci and Cn of 

 the table. C i is calculated from the emanation measured in 100 ccm. of the spring 

 gas a few hours after the gas was collected, while Cn is calculated from the 

 emanation measured in 200 ccm. of the spring gas after standing about four days 

 in the collecting bottles. 



Probably the first point which strikes one on considering the accompanying 

 table, is the great heterogeneity in the composition of the spring gases. Even samples 

 taken from springs in the same locality sometimes show a considerable lack of 

 uniformity in their composition. As a rule, however, springs in the same group 

 evolve gases of almost the same composition. In cases where there is great 

 incongruity in the gases, it will generally be found that there is a corresponding 

 incongruity in the appearance of the springs. On the whole, the outward condi- 

 tions and appearance of the springs seem to be to a great extent dependent on the 

 composition of the spring gases. Springs which evolve gas containing sulphuretted 

 hydrogen have generally a most unpicturesque appearance. The spring water 

 becomes turbid through dark mineral particles being suspended in the water. If 



