i879-1 
Proceedings of Societies. 
503 
The author’s eleven years’ work on this special branch has led 
him to the conclusion that all statements of coincidences be- 
tween metallic and solar lines with a lower degree of accuracy 
than that employed by Thalen and Young are to be avoided 
when possible, as they may be worse than useless — they may 
mislead. Although the map on which he was working was on 
twelve times the scale of Angstrom’s, it would have been better 
if it were larger ; and in saying this he adds his tribute of ad- 
miration of fhe accuracy of the work of those who have preceded 
him, notably Angstrom, Thalen, Cornu, and Young, with whose 
work he is more familiar, as it is expressed in wave-lengths. 
May 24. — “ Note on the Spectrum of Sodium,” by J. N. 
Lockyer, F.R.S. I have lately been engaged in studying the 
spectrum of sodium under new experimental conditions. In 
anticipation of a detailed communication I take leave to state 
that the vapour given off from the metal after slow distillation 
in a vacuum for some time shows the red and green lines without 
any trace whatever of the yellow one. Hydrogen is given off 
in large quantities, and at times the C line and the red 
“ structure ” are seen alone. After this treatment the metal, 
even when red-hot, volatilises with great difficulty. 
May 29. — “ Researches on Explosives. No. II. (Fired Gun- 
powder),” by Captain Noble, late R.A., F.R.S., F.R.A.S., F.C.S., 
and F. A. Abel, C.B., F.R.S., V.-P.C.S. The authors preface 
this memoir by two tables : one of these gives the results of 
some analyses of produces of explosion of the three services 
powders of Waltham Abbey manufacture — pebble, R.L.G., and 
F.G. — which are required to complete the series of results ob- 
tained by firing the charge in different spaces, which were given 
in their first memoir on this subject, and a statement of the 
mean percentage composition by volume of the gases and by 
weight of the solid products furnished by those three powders, 
together with the highest and lowest proportions in which each 
product has been obtained with the three descriptions of powder. 
This table includes the results of examination of the products of 
explosion of four descriptions of powder differing in many 
respects from the powders chiefly employed in their researches. 
The other table gives the complete results of the whole series 
of analyses made, showing the proportion by weight of each 
solid and gaseous product, and including the amount of water 
pre-existent in the various specimens operated on. A portion of 
this memoir is devoted to a discussion of a few points raised in 
reference to the first memoir of the authors,* on fired gun- 
powder, by General Morin and M. Berthelot, who were appointed 
by the Academic des Sciences as a Commission to report on 
Phil. Trans., 1875, Part l - 
