678 



REPORT — 1884. 



CaCS^, toj^ethor with a laiye excess of water. The pohition (if calcium sulpho. 

 carhoiiat e in water ini\c with lijdroehloric acid a red oil, prohahly sulphocarlionio 

 acid, described by Jter^oHu.s and Zeise, davli brown precipitates with sohitions df 

 Lisimilh, stannous, lead, copper, mercurous, silver, platinum and ^'old salts, ollv.' 

 green solutions with nickel and manganese salts, with zinc salts golden wbito 

 precipitates. These substances, some of which have been described by ller/eliii!:, 

 are presumably the sul])hocarbonates of the various metals. The author hopes 

 sliortly to enter into a more minute examination of the composition and chemical 

 ])ropcrties of these substances. 



11. On the Action of SuJphiirdtleJ ILjilrorjen iqion Silver. 

 1)1/ Professor F. P. Dunningi'OX. 



In view of thr' ra]ndity with which silver decomposes sulphuretted hydrngpu 

 under ordinary conditions, it ajipeared of interest to ascertain what would tiiki 

 place if water was completely e.xcluded. 



Three experimi-nts were nuide under varied conditions, the results of which 

 indicated that it was peculiarly ditlicult to reuiove all the moisture from the silver. 



A fourth experiment was made as follows : — a piece of pure silver was 

 flattened and carefully polished on each face, this was jdaced in the middle of a 

 two-foot glass tube, in each end of the latter was put a plug of five inches of 

 phosjihoric anhydride, couiined by gla«s wool. Pure dry hydrogen was slowly 

 passed tlirough this tube while it was gently heated througlKUit, t!ie hydrogen wa> 

 then removed by a .Sprengel pump, the silver Ijeing heatetl to about MUU^ C. ; again 

 dry hydrogen was let into the tube, and again exhausted while the silver was 

 heated; again hydrogen was let into the tuLe, and then jiure dry sulphuretted 

 hydrogen was slowly ])assed through the apjiaratus for an hour, and the tiihe 

 finally drawn olf and scaled at each end so as to leave the silver confined between 

 the plugs of phosphoric anhydride. After several days the silver was darkeneil 

 only a little near its edges, and after five months (as exhibited to the Section) the 

 silver is blackened on its edges, wliile the nniin portion of the surface is still white. 



Attention is also drawn to the fact that when the silver was heated to about 

 300° C, and the ^n-essura removed, the brilliant polish of the silver was destroyed 

 l)y a blistering of its surface, no doubt due to the oxygen which had been occluded. 



From the above we maj"^ infer that in absence of water silver does not decompose 

 sulphuretted hydrogen at common temperatures. The foregoing work was condwteil 

 by Mr. J. M. Cabell, a student in my laboratory. 



SATURDAY, AUGUST :(0. 

 The Section did not meet. 



MOXDAY, SEPTE^rnim 1. 



The following Reports and Papers were read : — 



1. Report of the Committee npon the inesent state of our hioidedge of 

 Spectrum Analysis. — See Reports, p. 295. 



2. Second Report of the Committee on Chemical Nomenclature. — • 



See Reports, p. 39. 



3. On Coal-Tar Colouring Matters. By W. H. Perkin, Ph.D., F.B.S. 



