Existence of certain Elements in the Sun. 329 



Tin. — The solitary tin-line at 4525, thought by Lockyer 

 to coincide, falls directly between two fine lines in the solar 

 spectrum. 



Silver. — Lockyer mentions a certain possibility of silver in 

 the solar atmosphere from the apparent agreement of two of 

 its nebulous lines with solar lines. One of these we have 

 never been able to find in the course of many photographs of 

 the region in which it is given by him. 



We find seven lines of silver between 4000 and 4900. Of 

 these seven, three are what Thalen calls nebulous ; so broad 

 and hazy that their true positions cannot be determined with 

 much accuracy. These lie at about 4055*5, 4063*6, and 4212. 

 A fourth line at 4023 is of the same general character, but 

 has a sharp reversal which agrees with a solar line. The 

 remaining three lines are represented in the sun, and are 

 given by Thalen in the spark-spectrum of the metal. 



4476*2. Yery strong line ; nebulous on lower edge. Sun- 

 line strong. (Thalen, 4475.) 



4668. Strong, solitary line. (Thalen, 4666'5.) 

 4874*3. Fairly strong. (Thalen, 4874.) 

 Thus, between the limits given above, every line of silver, 

 as far as can be determined, coincides with a solar line. 



Potassium. — We could find but two lines of potassium, the 

 same that were examined by Lockyer, 4044*5 and 4048*35. 

 Each line is reversed four times, which increases the difficulty 

 of locating them exactly. 4048*35 seems to agree with a solar 

 line. The solar line near 4044*5 is very faint, and it is next 

 to impossible to decide the question of an agreement. 



Lithium. — The blue line of lithium presents a curious case. 

 The very broad and nebulous line has a rather sharp reversal 

 near the centre, and somewhat toward the lower edge a 

 broader and less clearly defined reversal. Both these reversals 

 agree with solar lines at 4602*5 and 4603*2. It is possible 

 that one of the reversals may be due to the presence of some 

 other substance, say calcium ; but if that were true, it would 

 seem that both reversals would be nearly, if not quite, oblite- 

 rated. Further experiment may clear the matter up. 4603*2 

 is given to iron by Thalen. 



Platinum. — As far as we can learn, no evidence has hitherto 

 been offered to show the occurrence of this metal in the solar 

 atmosphere. We were somewhat surprised therefore upon 

 meeting with coincidences. Between 4250 and 4950 we find 

 64 lines of platinum, sixteen of which agree with solar lines. 

 The latter are at the following places : — 



Phil. Mag. S. 5. Vol. 24. No. 149. Oct. 1887. Z 



