of Edinburgh, Session 1868 - 69 . 
517 
magnesium lamp. The authors, however, have no hope of modif} r - 
ing the process in such a manner as to convert any considerable pro- 
portion of the nitrogen of the atmosphere into ammonia, a problem 
of the highest practical importance. Nevertheless, the formation 
of ammonia in this way is of considerable theoretical interest, espe- 
cially when viewed in connection with the source of the ammonia 
in nature, a question to which no satisfactory solution has yet 
been given. 
We purpose, when circumstances permit, to continue our expe- 
riments on the subjects indicated in this paper. 
The following Gentlemen were elected Fellows of the 
Society: — 
Principal Sir Alexander Grant, Bart. 
Captain T. P. White, Royal Engineers. 
The following alteration proposed by the Council on the 
Law relative to the Election of Honorary Fellows was 
adopted by the Society:— 
Law XII., lines 6 and 7, in place of the words, <{ and printed in 
the Circular for the meeting at which the ballot is to take place,” 
read, “ and printed in the Circulars for two ordinary meetings of 
the Society, previous to the day of election.” 
Monday , bth April 1869. 
Dr CHRISTISON, President, in the Chair. 
The following Communications were read : — 
1. On the Present State of the Sun’s Distance Question — 
continued. By W. Petrie, Esq. Communicated by Pro- 
fessor C. Piazzi Smyth. 
This paper is a compilation and discussion of all the best deter- 
minations of the sun’s mean distance and parallax within the last 
few years, and up to the present time. The comparative weights 
to be given to the different observations or results are entered into 
