208 M. Bineau on Vapour-densities. 
very accurate relation between the densities of the two vapours, 
the density of one of which is perfectly well established. 
The results arrived at were as follows :— 
Sulphur.—The vapour-density of this substance at 860° is 2:2. 
For the temperature 1040° the same number was also obtained 
in twelve successive experiments. Previous determinations of 
other experimenters had furnished the number 6:6, which gave for 
sulphur an atomic value } that of oxygen, phosphorus, &c. 
Various explanations have been offered to explain this anomaly, 
which is removed by Deville and Troost’s observations. 
Selenium.—Its vapour-density at 860° is 8:2; at 1040° it is 
6:37. Theory and analogy with sulphur require the number 
5:44, By making the determination at 12° to 1400° C., the 
authors hope to obtain this number. 
Phosphorus.—Vapour-density at 1040°, 4:8. Calculated, 4°4. 
Cadmium.—At 1040° the vapour-density is 3°94, For a 
condensation to two volumes the number 3°87 is required. 
Chloride of Ammonium.—At 1040° the observed vapour-density 
was 1:01. For a condensation to eight volumes the number 
3°87 is required. 
Bromide of Aluminium.—Vapour-density 18°62. Theory 
requires 18°51. 
Lodide of Aluminium.—The observed vapour-density was 27:0. 
The number required by theory is 27°8. 
Bineau has also published* some determinations of the densities 
of superheated vapours, executed upwards of ten years ago. 
The experiments were made in tubes placed in a sort of cylin- 
drical iron case, from which the finely drawn out extremities of 
the tubes projected. The capacity of each tube was determined 
before the experiment. The tubes were sealed by means of an 
oxyhydrogen flame. The tubes were covered with an argillaceous 
lute, and were surrounded by sand, or iron filings. The cylinder 
was placed horizontally on a grate, and heated as regularly as 
possible ; the temperature was determined by means of an air- 
thermometer; and in order to test the method, a control deter- 
mination of the density of mercury was made. It gave the 
number 67, which agrees well with 6°97, the number obtained 
by Dumas, and 6°91, the calculated number. A control deter- 
mination of the density of iodine gave the number 8°65. Dumas 
obtained 8°716, and the calculated number is 8°8. 
The numbers obtained for the density of sulphur vapour varied 
in nine experiments between 2°] and 2°8. These experiments 
may be divided into two groups; in one of these the temperature 
was below 800°, and the numbers were— 
* Comptes Rendus, vol. xlix. p. 799. 
