719 



glowed carefully ; after having been weighed the remainder was 

 extracted by hydrochloric acid, which was first distilled over chemic- 

 ally pure salt. After this treatment it was filtered, through which 

 a part of the solution to be made, viz.: the acid solution had been 

 obtained. The filter was burnt, the ashes with the dried residue 

 mixed in a platinum crucible with 5 grammes of Na^COj and 

 5 grammes of K^COg. ^) The amalgamation of this mixture took 

 place in a small electric furnace heated for this purpose to about 

 800 degrees for at least three hours. 



Subsequently this melt of molten mass was extracted by water 

 and filtered in such a way that a perfectly pure alkaline solution 

 was obtained. The remainder was dissolved in strong hydrochloric 

 acid and added to the acid solution obtained first, the alkaline solution 

 being preserved separately. If, however, not evei-ything was dissolved 

 completely, it was filtered once more, the residue amalgamated with 

 only a little carbonate aud treated again as mentioned above; finally 

 these acid and alkaline solutions were added separately to those 

 prepared first. The solutions obtained i. e. of each sample an acid 

 and an alkaline, were shut off air-tight in a one-litre boiling flask 

 of Jenaglass and put away in order to await the emanation equilibrium, 

 which is almost perfect after 50 days. Even after this time the 

 solutions were still found in an entirely clear state and consequently 

 the chance of occlusion for the formed emanation into a gelatinous 

 precipitate, was absent. 



As a second part of the investigation now followed the expulsion 

 of the emanation, which was brought about with the assistance of 

 an arrangement with which the various solutions were made to 

 boil and from which in consequence the emanation could develop 

 itself. This together with the escaped gases — the vapour was 

 condensed in a cooler — were caught into a reservoir over a 

 satnrated salt solution. From this the emanation was transferred to a 

 jar communicating with a second in order to make the absorption 

 of gas possible, then all the tubes were rinsed again with air and 

 at last the top of the jar shut off. The emanation which was again 

 present here over a saturated salt solution, was then ready to be 

 investigated electrically. 



Hereupon followed the third and last phase of the investigation, 

 viz: the measurement of the ionisation current, caused by the ema- 

 nation described above. For these electric measurements as well as 

 for those according to the "direct method", the electrometer was 



1) Provided by Kahlbaum "pro analyse" with "Garantieschein." 



