Chemical History of Mercury, 297 



year 1822, have not hitherto been submitted to analysis, nor exa- 

 mined with much precision. Mr. Hennell has already obtained 

 some interesting eesults upon this subject, of which we hope to be 

 able to give an account on a future occasion. In examining the 

 mutual action of muriate of ammonia and corrosive sublimate, his 

 attention was naturally directed to the substance usually called 

 wliite "precipitate, the " Hydragyrura prsecipitatum album," of the 

 Pharmacopceia ; his experiments appear to me to leave little doubt 

 that it consists of one proportional of peroxide of mercury, and one 

 of muriate of ammonia*. 



W. T. B. 



* Having inferred from previous experiments, that the " white precipitate" 

 was a compound of one proportional of peroxide of mercury and one of mu- 

 riate of ammonia, Mr. Hennol verified his opinion as follows. A solution 

 of one proportional of corrosive sublimate ( =: 272) was mixed with a quan- 

 tity of solution of ammonia, containing two proportionals (17 X 2 = 34) of 

 that alkali; a neutral mixture resulted, white precipitate was formed, and one 

 proportional of muriate of ammonia, (ammonia 17 + muriatic acid 37 =54 of 

 muriate of ammonia) was found in solution. In this case, the 2 proportionals 

 of chlorine in the sublimate (36 X 2 = '72) were converted, at the expense of 

 2 proportionals of water, into 2 of muriatic acid, which, imiting with the 

 ammonia, formed 2 of muriate of ammonia. The 2 proportionals of the oxy- 

 gen from the water (equivalent to the 2 of hydrogen transferred to the chlo- 

 rine) united to the 1 proportional of mercury in the sublimate, to form 1 of 

 peroxide of mercury, which fell in combination with 1 of muriate of ammonia 

 to constitute white precipitate ; while the other proportional of muriate re- 

 mained as above stated in solution. The equivalent number, therefore, of 

 white precipitate, is 270, and it consists of 



1 proportional of peroxide of mercury = 216 80 



1 muriate of ammonia = 54 20 



270 100 



Having thus synthetically established the composition of white precipi- 

 tate, the following analytical experiment was made upon it; 270 grains 

 were dissolved in hydrocyanic acid, and sulpliuretted hydrogen was passed 

 through the solution till it occasioned no further change ; the precipitate was- 

 then collected, washed, and dried; it weighed very nearly 232 grains, being 

 the equivalent of bisulphuret of mercury. The filtered liquor, on evapora- 

 tion to dryness, left 54 grains, or 1 proportional of muriate of ammonia. 



Vol. XVIII. X 



