Mr. Gore on the Properties of Electro-deposited Antimony. 479 



The determination of the optical constants of these substances 

 leads to many interesting conclusions ; among which the following 

 may be stated :— 



1 . That transparent bodies, as well as metals, possess a coefficient 

 of reflexion, which is sometimes very sensible, although there are 

 bodies in which it is very small. 



2. That Silver is the only substance which possesses the qualities 

 of brilliancy and lustre, represented by the coefficients of refraction 

 and reflexion, in a high degree. 



3. Of the metals which have high brilliancy and little lustre may 

 be named Mercury, Palladium, Zinc, and Iron. 



4. Of the metals which have high lustre and little brilliancy 

 there are only two, Gold and Copper. 



5. Results of the highest interest appear from an examination of 

 the optical constants of the alloys of copper and zinc, which cannot 

 be given in an abstract. 



6. In the details of the several experiments, the author calls atten- 

 tion to several remarkable laws, or indications of laws, which appear 

 to him to require some notice from theorists. 



a. When the azimuth of the incident beam is less than the circular 

 limit, the axis major of the reflected ellipse, at the principal incidence, 

 lies in the plane of incidence ; but when the azimuth is greater than 

 the circular limit, it is perpendicular to the plane of incidence, and 

 as the incidence varies, the axis major twice approaches to a minimum 

 distance from that plane. 



b. There appears to the author to be some indication in the expe- 

 riments on metals, that the quantity known to theorists as ( y J is, 



not a function of the incidence only ; a conclusion which, if correct, 

 would require the intervention of a third wave suppressed, or some 

 such theoretical supposition, to account for it. 



" On the Properties of Electro-deposited Antimony ." By George 

 Gore, Esq. 



In this communication the author has described two additional 

 kinds of electro-deposited antimony possessing the property of evol- 

 ving heat ; one of them is obtained from a solution of bromide, and 

 the other from a solution of iodide of antimony ; there is also given 

 additional information respecting the peculiar heating-antimony ob- 

 tained from the aqueous terchloride. 



The following is a brief statement and comparison of some of the 

 properties of the three kinds of thermically active antimony. The 

 specific gravity of the chloride deposit is 5*8, the bromide one 5*44, 

 and the one from the iodide 5 "25. The amount of heat evolved is 

 greatest with the one from the chloride solution, and least with that 

 from the iodide ; the former evolves all its heat at 60° Fahr., by 

 contact with a red-hot wire, the bromide one at 280° Fahr., whilst 

 the iodide one requires a temperature of 340° Fahr. ; the latter also 

 acquires a reddish-brown colour by exposure to solar light. 



The chloride deposit contains about 6*3 per cent, of saline matter, 

 2K2 



