of Hydrogen and some other Gases. 323 



changes from a paramagnetic to a diamagnetic during 

 melting. Since that time no other substance showing a 

 similar change has been found. Meantime Mr. T. Xshiwara 

 in our laboratory found in the course of* his researches on 

 the magnetic susceptibility of chemical substances at low 

 temperatures, that solid carbon dioxide has a diamagnetic 

 susceptibility per unit mass of ^= — 0*42 x 10~ 6 in the 

 temperature range between — 100° C. and — 170° C. 



In the literature we have only a few data for the magnetic 

 susceptibility of the gaseous carbon dioxide. The earlier 

 investigators, such as Faraday * and Becquerel f, agreed in 

 the view that the magnetism of gaseous carbon dioxide is too 

 weak to be detected by their experiments. Quincke { found, 

 however, that its specific susceptibility is %= +0*017 x 10" 6 ; 

 more recently Bernstein § found its volume susceptibility to 

 be k= +0-0002 x 10" 6 . If these two results be true, at 

 least in sign, then gaseous carbon dioxide is paramagnetic, 

 and we have, besides tin. one more example of a magnetically 

 anomalous substance. In this respect an exact determination 

 of the susceptibility of the gaseous carbon dioxide seemed 

 very interesting. 



In the present experiment the carbon dioxide was 

 obtained by the reaction of dilute hydrochloric acid on 

 calcium carbonate. Pieces of pure marble previously boiled 

 in hot water for about 24 hours in order to drive off the air 

 occluded, were put in a Kipp apparatus with boiled distilled 

 water, care being taken not to expose the pieces to the air. 

 Xo air bubble was allowed to remain in the bottle. Then 

 the strong hydrochloric acid was poured into the apparatus 

 through the upper opening, and at the same time, by 

 expelling the water from the exit, we could easily replace 

 the water with hydrochloric acid of a moderate strength 

 without introducing any trace of air into the apparatus. By 

 this means we were able to obtain the carbon dioxide entirely 

 free from air. Before introducing the gas generated in the 

 Kipp apparatus into the compressing cylinder, it was first 

 passed through a bottle containing water, and then bottles 

 containing strong sulphuric acid and pieces of calcium 

 chloride. In the following table one set of observations is 

 given as an example. 



*M. Faraday, toe. cit. t E. Becquerel, he. cit. 



I q Quincke, loc. cit. § Bernstein, Diss. Halle, 1909. 



Y 2 



