130 Mr. Vh'iWips on a 7iexv Salt obtained bi/ the 2^artial 



With respect to perchloride of mercury, if it does not 

 become bipermuriate by solution in and decomposition of 

 water, it appears to me that the excess of chlorine should de- 

 stroy vegetable colours : but this is so far from being the case, 

 that litmus paper is reddened by the solution precisely as it is 

 by any acidulous salt. It occurred to me also, that if the salt 

 remains a perchloride in solution, we might probably even in 

 that state, by abstracting half the chlorine, reduce it to proto- 

 chloride or calomel, as in the dry way, by the addition of mer- 

 cury. 



It is however well known that potash, soda, and lime-water 

 precipitate peroxide of mercury from a solution of cori'osive 

 sublimate ; but as the action of the carbonated is in many cases 

 different from that of the caustic alkalies, and as they decom- 

 pose some bisalts without converting their bases into carbo- 

 nates, I added carbonate of lime to a solution of corrosive 

 sublimate, and heated the mixture : to my surprise a dark- 

 coloured precipitate was soon formed, and I supposed, at first, 

 not only that an atom of chlorine had been separated, but 

 that the carbonate of lime had occasioned the deposition of 

 protoxide of mercury, by extending its action to the proto- 

 chloride formed, — an effect which it is not perhaps generally 

 known that it is capable of producing to a certain extent. On 

 examination I found that the action which had occurred was 

 very different from what I had imagined ; the precipitate was 

 crystalline, extremely heavy, and of so dark a colour that the 

 larger crystals appeared nearly black. It was ver}^ sparingly 

 soluble even in boiling water, and scarcely at all in cold, so 

 that the hot solution deposited crystals on cooling. It was readily 

 dissolved by acids, and the solution in acetic acid yielded per- 

 oxide of mercury by potash, and chloride of silver by the ni- 

 trate. 



To ascertain whether the whole of a given portion of cor- 

 rosive sublimate could be decomposed by carbonate of lime, 

 I boiled equal weights of these substances in water for a con- 

 siderable time: on adding potash to the solution, an abundant 

 precipitate of peroxide of mercury was obtained, showing that 

 a portion of the mercurial salt remained undecomposed, al- 

 though the carbonate contained lime enough to saturate nearly 

 three times as much muriatic acid as the chlorine of the 

 sublimate could yield. It appears therefore that counteraction 

 takes place as long as the muriate of lime formed remains in 

 solution, and complete action is prevented, just as the pre- 

 sence of the resulting sulphate of potash hinders the total de- 

 composition of sulphate of barytes when it is boiled in a solu- 

 tion of carbonate of potash. I found also that the solution by 



evaporation 



