1878.] Analysis in connexion with the Sjiectrum of the Sun. 179' 



exist, from the regions of highest to those of lowest temperature in 

 our central luminary. 



Fia. 7. 













SUN 











CHROMOSPHERE 











JAR SPARK 









SPA RK with our JAR 







FEEBLEST SPARK AT 

 LOWEST PRESSURE 



COOLER STILL 



Summation of the above Series of Facts. 



I submit that the facts above recorded are easily grouped together T 

 and a perfect continuity of phenomena established on the hypothesis 

 of successive dissociations analogous to those observed in the cases of 

 undoubted compounds. 



The other Branches of the Inquiry. 



When we pass to the other possible evolutionary processes to which 

 1 have before referred, and which I hope to discuss on a future 

 occasion, the inquiry becomes much more complicated by the extreme 

 difficulty of obtaining pure specimens to work with, although I should 

 remark that in the working hypothesis now under discussion the 

 cause of the constant occurrence of the same substance as an impurity 

 in the same connexion is not far to seek. I take this opportunity of 

 expressing my obligations to many friends who have put themselves 

 to great trouble in obtaining specimens of pure chemicals for me 

 during the whole continuance of my researches. Among these I must 

 mention Dr. Russell, who has given me many specimens prepared by 

 the lamented Matthiessen, as well as some of cobalt and nickel pre- 

 pared by himself; Professor Roscoe, who has supplied me with vana- 

 dium and caesium alum ; Mr. Crookes, who has always responded to 

 my call for thallium ; Mr. Roberts, chemist to the Mint, who has 

 supplied me with portions of the gold and silver trial plates and 

 some pieces of palladium ; Dr. Hugo Miiller, who has furnished me 

 with a large supply of electrolitically- deposited copper; Mr. Holtz- 

 man, who has provided me with cerium, lanthanum, and didymium 

 prepared by himself ; Mr. George Matthey, of the well-known metal- 

 lurgical firm of Johnson and Matthey, who has provided me with 

 magnesium and aluminium of marvellous purity ; while to Mr. Valen- 

 tin, Mr. Mellor, of Salford, and other friends, my thanks are due for 

 other substances. 



I have already pointed out that a large portion of the work done in- 



