432 Mr. Nevins on the Heduction of the Chlorides of Mercury. 



amined. The results of some experiments on this subject I 

 beg leave to hand you, and to request the favour of their in- 

 sertion in your Magazine. 



When Hg CI and Hg CP are mixed with vegetable sub- 

 stances, as bread crumb, sugar, &c., and exposed to heat in a 

 test tube, a series of decompositions more or less complex en- 

 sues, and metallic Hg sublimes. 



In both these cases the theory of the reduction seems to be 

 the same. Water, or in some cases some other compound of H, 

 is decomposed, and the H, when in the nascent state, com- 

 bines with the CI in the compound, forming H CI, which is 

 driven off, and condensed by the water in the receiver, ren- 

 dering it distinctly acid to test paper, and which is proved to 

 be H CI by the usual tests. Water and empyreumiatic oil 

 are also formed as in other cases of vegetable decomposition. 

 The H would seem to be the only essential reducing agent, 

 for when Hg CI was mixed with pure charcoal, and a few drops 

 of oil of lemons were added, the reduction took place very 

 readily on the application of heat, with formation, as in other 

 instances, of H CI ; and the same result was obtained when the 

 experiment was repeated with the omission of the charcoal. 



The effect of the presence of water in producing the re- 

 duction of the Hg was strikingly shown in the following ex- 

 periments. When dry Hg CI and charcoal were mixed and 

 exposed to heat, no decomposition ensued; but on the addition 

 of a few drops of water, H CI and C O^ were formed and 

 Hg was sublimed. 



It seems probable that it is only while in the nascent 

 state that H possesses the power of decomposing Hg CI, for 

 when a stream of H gas was passed over Hg CI, heated either 

 by itself or when mixed with charcoal, no reduction took 

 place ; while when Hg CI was introduced into a vessel con- 

 taining the materials for forming H, it was decomposed si- 

 milarly to Ag CI. When Hg CP was subjected in a similar 

 manner to the action of nascent H, it was first converted into 

 Hg CI, and afterwards by continuing the process it was re- 

 duced to the metallic state. 



The same results were obtained in all the experiments, 

 which were made with rhubarb, bread crumb, pure sugar 

 and other vegetable substances, and with moistened char- 

 coal. 



In some of these cases, upon boiling the residue after the 

 sublimation of the Hg, a small quantity of Ca Ci was de- 

 tected ; but as even in these cases free H CI was evolved and 

 collected, it is evident that the Ca was not the reducing 

 agent. 



