184 s - HADA; HOW MERCUROUS AND 



is only second in scientific importance to the union of chlorine with 

 mercury. To see given, as it is, a whole list of metals that convert 

 'mercuric chloride in solution into mercurous chloride, which includes 

 silver but does not include mercury itself, is certainly strange. 



Dissociation of mercurous chloride by heat. — The experiments made 

 upon the dissociation of mercurous chloride were closely similar to 

 those upoD the nitrate. The mercurous chloride used had been 

 precipitated by hydrochloric acid from the nitrate and well washed. 

 One gram of it and lOcc. water heated seven hours in a flask im- 

 mersed in boiling water, gave a sublimate of mercury in the condenser 

 tube, a little of which rolled back into the flask. From first to last a 

 gentle current of air was passing. The mercury found in solution as 

 mercuric chloride was .0983 gram, and that collected from the 

 condenser tube about .08 gram ; the rest could not be collected. 

 That the deficiency in the latter, or excess in the former, was incidental 

 and not significant of oxidation, the next and some of the other 

 experiments will show. A second experiment performed simul- 

 taneously with the last, and like it in everything except that a current 

 of carbon dioxide was used in place of that of air, gave .1008 gram 

 mercury in solution and about .08 gram sublimed in the tube. Again, 

 an experiment was made in a current of air, but lasting eight hours 

 and in which a little hydrochloric acid had been added to the water. 

 This time, the mercuric radical was found to be .1307 gram, and the 

 sublimed mercury secured, .1305 gram. The hydrochloric acid had 

 seemingly increased slightly the extent of the dissociation. Two ex- 

 periments were made, using dilute solution of potassium chloride 

 instead of water. In one case, air was passed ; in the other, carbon 

 dioxide. The heating lasted six hours. In the air experiment, .1923 

 gram mercury was found in solution as mercuric chloride, and .1763 

 gram mercury as sublimate. In the carbon dioxide experiment, the 



