140 Mr. J. N. Lockyer. Note on Spectrum of Sodium. [May 29, 



physical significance, but are still approximately applicable, at the 

 high temperatures and pressures they have been considering. 



At all events, whether they are right or wrong in taking this view,, 

 it appears to them certain that the rules and tables they have laid 

 down, as based on their analyses, experiments, and calculations, may 

 for all practical purposes be accepted as correct, and may, bearing in 

 mind the restrictions to which they have referred in this memoir, be 

 applied to nearly every question of Internal Ballistics. 



(Received June 4, 1879.) 



Since the authors completed their memoir, a charge of 101b. of 

 P powder has been fired in 50 per cent, space. The solid products 

 were collected in the form of an exceedingly hard mass, weighing 

 about 3flb., the fracture of which exhibited the want of homogeneity 

 frequently alluded to by the authors. On the surface there was a 

 deposit of varying thickness, and of a pale yellow colour, consisting 

 chiefly of small crystals. The chemical examination of a portion of 

 this deposit, rapidly collected, showed it to contain a considerable 

 proportion of potassium hyposulphite. This product was exhibited 

 to the Royal Society when the paper was read. 



Y. "Note on the Spectrum of Sodium." By J. NORMAN 

 Lockyer, F.R.S. Received May 28 ? 1879. 



I have lately been engaged in studying the spectrum of Na 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. 



The Society adjourned over the Whitsuntide Recess to Thursday, 

 June 12, the day appointed for the election of Fellows. 



