Apart from what can be learned from the study of their density, little is known as to the constitution in the state of vapour of those elements which are solid or liquid at ordinary temperatures. In a paper read before the Society early last year we showed that interesting information on this subject can be obtained from the examination of the absorption spectra of sulphur. In the present paper we propose to give an account of the application of the method to other elements. Unfortunately, the number of elements which lend themselves to the purpose is small, being limited to those which do not attack silica at a high temperature and volatilise below 1300°-1400°C., the temperature at which silica begins to soften. Those most suitable for examination, besides the members of the sulphur group, are the mercury group, comprising mercury, zinc, and cadmium, in which the molecules are known to be mainly monatomic at all temperatures above their boiling points, and the phosphorus group, comprising phosphorus, arsenic, and antimony, in which the molecules are tetratomic. The apparatus and arrangements employed in the investigation were similar to those described in the paper on sulphur, except that the tubes were exhausted as completely as possible by the Sprengel pump.