Dr. A. Schuster on Unilateral Conductivity, 251 



But I may remark that the peculiar properties and great com- 

 plexity of this compound offer considerable difficulties in the 

 way of an exact determination of its different constituents, and 

 of its true nature as a chemical combination. It appears, how- 

 ever, from the circumstance that it readily dissolves in alkaline 

 solutions, which then yield insoluble or sparingly soluble dark- 

 coloured precipitates with different metallic salts, that it partakes 

 somewhat of the character of an acid ; but this and several other 

 obvious matters of inquiry connected with the compound are 

 subjects for further investigation. 



Before concluding, it is right to state that, after I had observed 

 many of the facts which I have here described, I found, on look- 

 ing over the c Chemical News/ that there was in volume xxv. 

 page 37, a notice of a communication " On the Reaction of 

 Chloral Hydrate and Sulphide of Ammonium/'' which had been 

 read by Dr. J. Walz before the Lyceum of Natural History of 

 New York, in which he notices some of the changes which I 

 have described as taking place in that reaction, as well as the 

 formation of a light-yellow substance, the properties of which 

 (as observed by him) do not altogether agree with those of the 

 sulphuretted compound, which I prepared in a somewhat differ- 

 ent manner from that which he adopted. I may also add that 

 Dr. Walz did not attempt to analyze the substance he obtained, 

 for want, as he says, of material — and that he farther states, in 

 speaking of it, that 0. Low asserts that in physical appearance 

 and chemical properties it resembles exactly the sesquisulphide 

 of carbon which he has described in the American Journal of 

 Science, vol. xli. p. 251. 



Be this as it may as regards the substance obtained by Dr. 

 Walz, my analyses of the brown sulphuretted compound, pre- 

 pared in the manner stated, show that it possesses a totally dif- 

 ferent chemical composition from the sulphide described by Low 

 in the Journal to which he has referred. 



XXXVI. On Unilateral Conductivity, 

 By Arthur Schuster^ Ph,D.* 



I. Introductory, 



WHILE I was engaged in other work I met with an irre- 

 gularity which seemed to me to be of such a peculiar 

 nature that I subjected it to a separate investigation. The 

 results of this investigation have not been entirely satisfactory. 

 I have not been able to raise the phenomenon, to which I allude, 



* Communicated by the Author, having beeu read iu Section A. of the 

 British Association at Belfast (187-1). 



