235 
of Edinburgh,, Session 1882-83. 
hydrogen ; and, in order to ascertain the uniformity in composition 
of nitroglycerine, the nitrogen of samples prepared by various 
methods was estimated. The nitroglycerine was both pure and 
thoroughly dried. For the determination of the nitrogen, modifica- 
tions of Dumas’s method and of Schloesing’s method were em- 
ployed. The carbon and hydrogen were estimated by a modification 
of Liebig’s method. Every precaution was taken to insure that the 
results obtained should be correct. The average of the determina- 
tions gave 15'91 per cent, of carbon, 2'49 per cent, of hydrogen, 
and 18 ‘05 per cent. (Dumas) or 18T4 per cent. (Schloesing) of 
nitrogen. Theoretically nitroglycerine, regarded as the tri-nitrate 
of glyceryl, contains 15 ‘86 per cent, of carbon, 2*20 per cent, of 
hydrogen, and 18*50 per cent, of nitrogen. The quantities obtained 
by experiment agree so closely with the theoretical quantities that 
they may be regarded as affording proof that nitroglycerine is, in 
reality, the tri-nitrate of glyceryl The authors also conclude, from 
the unvarying amount of nitrogen obtainable from variously pre- 
pared specimens of nitroglycerine, including one from Nobel’s dyna- 
mite, that nitroglycerine is constant in composition and does not 
contain any of the lower nitrates of glyceryl, unless very imperfectly 
washed. 
BUSINESS. 
The President, at the close of the meeting, gave a brief review of 
the Session. He said there had been four Papers on Astronomy, 
two on Botany, seven on Chemistry, two on Geology, four on 
Mathematical subjects, six on Meteorology, twenty-three on Natural 
Philosophy, nine on Natural History, three on Philology, two on 
Political Economy, and one on Physiology — sixty-three papers in 
all, independently of the Obituary Notices which had been read. 
He thought he was not wrong in saying these papers had combined 
an amount of interest, ability, and novelty which could hardly be 
excelled, and to a very large extent showing great progress in the 
subjects treated. He congratulated the Society on having reached 
the point at which they now stood that night. The Session, he 
believed, had been a very successful and a very interesting one, and 
the topics treated of had been of the greatest possible importance. 
He said, in opening the Session, that it was the 100th Session 
