130 



Lord Rayleigh. 



[June 15, 



widely different physical conditions. As the temperature of the flame 

 of cyanogen probably approaches the temperature of the carbon poles 

 of the electric arc, and as we have shown that carbon undoubtedly 

 exists in the form of vapour in the arc discharge, from the fact of 

 the ultra-violet line spectrum being present, the question naturally 

 arises, is carbon present in the form of vapour in the cyanogen flame ? 

 In order to answer this question we have taken photographs of the 

 ultra-violet spectrum of the cyanogen flame fed with oxygen, and with 

 long exposures have had no difficulty in detecting one of the strongest 

 carbon lines, viz., that at 2478'3, along with a trace of what may be 

 the pair of lines at 2837, but more probably is a mercury line. No 

 other carbon line was found in the photographs. It seems, therefore, 

 proved that carbon vapour does exist in the flame of cyanogen, 

 although to a much smaller extent than in the arc discharge. Observa- 

 tions must be made on the spectra of flames under high pressures, in 

 order to solve many problems connected with spectroscopic enquiry, 

 and this subject we hope to discuss in a future communication. 



XIII. f ' Further Observations upon Liquid Jets, in continuation 

 of those recorded in the Royal Society's ' Proceedings ' for 

 March and May, 1879." By Lord Rayleigh, F.R.S., Pro- 

 fessor of Experimental Physics in the University of Cam- 

 bridge. Received June 8, 1882. 



The experiments herein described were made in the spring and 

 summer of 1880, with the assistance of Mrs. Sidgwick. Section 2 

 was indeed written out as it now stands in August of that year.. 

 There were some other points which I had hoped to submit to 

 examination, but hitherto opportunity has not been found. 



On some of the Circumstances which influence the Scattering of a nearly 

 Vertical Jet of Liquid. 



§ 1. It has been already shown that the normal scattering of a 

 nearly vertical jet is due to the rebound of the drops when they come 

 into collision. If, by any means, the drops can be caused to amalga- 

 mate at collision, the appearance of the jet is completely transformed. 

 This result occurs if a feebly electrified body be held near the place of 

 resolution into drops, and it was also observed to follow the addition 

 of a small quantity of soap to the water of which the jet was com- 

 posed. In trying to repeat the latter experiment in May, 1880, at 

 Cambridge, I was astonished to find that even large additions of soap 

 failed to prevent the scattering. Thinking that the difference might 



