484 



Dr. Tycho E:son Auren on the 



point o£ view, there seem to be various reasons why the former 

 place should be appropriate to Ni in the periodical system. 

 X. a. k. for Ni being greater than for Co, is consequently in 

 in good agreement with what is hitherto known about this 

 metal. For Mg and Al I have found approximately the 

 same value of X. a. k., but this certainly depends upon an 

 experimental error, and even a slight one can in this case 

 be rather mischievous, first because the difference between 

 X. a. k. for both metals is a slight one, and again because 

 X. m. k. of the respective salts is mainly determined by the 

 acid radicals. 



From the Tables Y. and VI. it appears that X. a. k. for Al, 

 Ni, Fe, and Cu has got very closely the same value, whether 

 the values are calculated from the experiments on the re- 

 spective elements in the metallic state or in the form of salts. 

 From the values for Na and Zn it is clear that X. a. k. is, 

 within experimental error, independent of any chemical 

 combination the constant may be deduced from. These 

 experiments consequently confirm what has been generally 

 admitted in regard to absorption of X-rays : that it does not 

 depend on any state of aggregation or any way of chemical 

 combination. 



In the following table there are given the values found by 

 the author for X. m. k. for a solution of FeS0 4 of different 

 concentrations, with the calculated values of X. a. k. for Fe ; 

 X. m. k. of the S0 4 ion being, according to the values in 

 in Table VI., 11'4. 



Table VII. 



Number of 



gram-molecules 



per 1. 



Thickness of 

 water sheet 



X. ra.k. 



X.a.k. 



1-08 



1-03 



53-0 



41-6 



0-81 



0-78 



53-4 



42-0 



0-54 



0-55 



56-5 



45-1 



0-41 



0-42 



56-8 



45-4 



0'27 



0-28 



57-6 



46-2 



0133 



014 



58-4 



47-0 



From the table we see that while concentration is de- 

 creasing, the value of X. m. k* is continually increasing, 

 which seems to be owing to the fact that the salt, being 



