1887.] Evaporation and Dissociation. Sun-Spots. 



37 



The paper is illustrated by three plates, the first giving the sea- 

 level distribution of pressure and the wind directions all over India, 

 the second the distribution of pressure at a height of 10,000 feet, 

 and the third the curves of temperature decrement on ascending, both 

 as given by observation in Grlaisher's balloon ascents, and as computed 

 on the hypothesis of adiabatic convection. 



II. " Evaporation and Dissociation. Part V. A Study of the 

 Thermal Properties of Methyl Alcohol." By William 

 Ramsay, Ph.D., and Sydney Young, D.Sc. Communicated 

 by Professor G. G. Stokes, D.C.L., P.R.S. Received 

 January 6, 1887. 



(Abstract.) 



This is a continuation of the investigation in which the authors are 

 engaged. The measurements include the expansion of the liquid, the 

 prjssure of the vapour, and the compressibility of the substance in 

 the gaseous state ; and from these are deduced the densities of the 

 saturated vapour and the heats of vaporisation. The total range of 

 temperature is from —15° to +240°; the range of pressure, from 

 11 mm. to 60,000 mm. The conclusions announced in their previous 

 papers are supported by these measurements. The apparent critical 

 temperature is 240*0°, and the critical pressure about 59,700 mm. 



III. " Further Discussion of the Sun-Spot Observations made at 

 South Kensington." By J. Norman Lockyek, F.R.S. 

 Received January 8, 1887. 



In papers communicated to the Royal Society, and printed in the 

 'Proceedings' (vol. 31, pp. 72 and 348; vol. 32, p. 203; and vol. 33, 

 p. 154) the sun-spot observations made at South Kensington since 

 1879 have been to some extent discussed. 



In the last paper communicated to the Society, in May, 1886, I 

 discussed the results obtained by the reduction of the observations of 

 the most widened lines in the region F to b for the whole number of 

 observations (700) made from November, 1879, to August, 1885. 



In the latter paper it was shown that as we pass from the minimum 

 to the maximum period included in the years named, the lines of 

 known terrestrial elements disappear, their places being taken by 

 lines which do not appear in any maps or tables of spectral lines. It 

 was pointed out that such a result might be explained on the. supposi- 

 tion that since the solar atmosphere is quietest and coolest at the 



