some Copper Salts in Aqueous Solution. 



335 



The refractive indices of the solutions were determined for 



sodium light as follows :- 



Substance. 



Concentration. 



Refractive Index. 



CuS0 4 



2-1 

 0-28 

 4-2 

 2-1 



1-365 

 1-336 



1-388 

 1-362 





OuCl, 







Table IX. contains the absorption-ratios of all the solutions 

 examined. The absorption-ratio for any substance in solutions 

 of different concentration can be regarded as constant when 

 the differences of concentration are small. The mean, there- 

 fore, of the numbers obtained with the solutions of nearly the 

 same concentration has been taken. 



Table IX. 





CuS0 4 . 





CuCl 2 . 





Cu(N0 3 ) 2 . 



Position in 

 Spectrum. 































2eq. 



0-28 eq. 



4 eq. 



2eq. 



0-4 eq. 

 1-92 



4 eq. 



035 eq. 



\. A. 



627-7—599-4 



1-89 



1-79 





1-86 





1-96 



599-4—574-2 



385 



3-41 



3-86 



355 



374 





3-77 



574-2—551-6 



6-66 



6-81 



6-84 



6-68 



6-88 



5-68 



6-09 



551-6—5341 



1295 



12-65 



1395 



13-41 



1319 



11-46 



11-91) 



534-1— 5182 



23-51 



2205 



27-20 



25-23 



23-99 



21-83 



23-56 



518-2—502-3 



45-63 



40-45 



53-70 



46-20 



42-69 



37-80 



4617 



502-3-488-3 



8997 



82-73 



73-92 



85-26 



77-87 



67-52 



92-57 



488'3— 474-6 



181-9 



143-2 



43-24 



120-4 



135-2 



106-9 





474-6—462-8 



316-9 





23-39 



107-0 





155-8 





4628-452-2 



485-2 





11-03 



64-99 





168-4 





452-2—4431 



595-8 





6 26 



36-20 





180-8 





443-1—4342 



523-0 







21-25 





160-6 





434-2—427-0 



516-7 







]400 





143-2 





The absorption-spectrum of copper sulphate has already 

 been measured by Glan *. He has given his results in the 

 form of fractions of light transmitted — (the quantity which I 

 have called (1— p). The light, in Glan's experiments, passed 

 vertically upwards through a glass trough, in the lower part 

 of which was a layer of strong copper sulphate solution, and 

 floating upon this a layer of distilled water. The fraction of 

 the light transmitted was measured, the water and solution 

 mixed together, and the measurement repeated. In order to 

 compare my numbers with those of Glan I have calculated 



* Glan, Wied. Ann. iii. 

 2A2 



p. 54(1878). 



