288 Mr. T. E. Thorpe on the [Feb. ] 7, 



The mean of three experiments gives the specific gravity of vanadyl 

 trichloride at 0°, compared with water at 4°, as 1*86527. Eoscoe found 

 126°- 7 for the boiling-point of this compound, and for its specific 

 gravity 



1-841 at 14°-5 reduced 1*8655 at 0° 



1-836 at 17°'5 „ 1-8653 „ 



1-828 at 24° „ 1-8665 „ 



The reduced sp. gr. (S ) in this and the following cases has been calcu- 

 lated by means of the expression 



^° = S'Y' 

 in which 



S,=the sp. gr. at the higher temperature t, 



V=the volume of the liquid at t, obtained by the interpolation 



formula. 

 V = volume of the water at £(vol. at 4°=1), obtained from Eossetti's 

 Tables*. 



The indications of the dilatometer have been controlled by determining 

 the degree of expansion suffered by the vanadyl trichloride on being 

 heated in the specific-gravity bottle from 0° to near 100°, i. e. in the steam 

 from boiling water. The details of the experiments are as follows : — 



Experiment I. Weight of VOCl 3 at 10° in vacuo 7*15114 grams. 

 Weight of YOCl 3 in vacuo after 



having been heated to 100°-37. 



Bar. 770-3 millims 6-46541 „ 



Expansion of glass for 1° -00002633 



Hence 10,000 vols, at 0° become at 100°-37— 



Observed 11090 



Calculated from formula 11091 



Experiment II. Weight of YOCl 3 at 0° in vacuo 7-15156 grams. 

 Weight of VOCl 3 in vacuo after 



having been heated to 100°- 10. 



Bar. 762-9 millims 6-46736 „ 



Expansion of glass for 1° -00002633 



Hence 10,000 vols, at 0° become at 100°-10— 



Observed 11087 



Calculated from formula 11088 



The agreement between the results is satisfactory. The control is 

 important, since it might be supposed, from Matthiessen's criticism of 

 Kopp's observations on the expansion of water, that the dilatometric 



* Ann. de Chim. et de Phys. x. 1867, xvii. 1869. Mean results of the observations 

 of Kopp, Pierre, Despretz, Haagen, Matthiessen, Weidner, Kremers, and jRossetti. 



