Ml*. R. Phillips's Analijsis of some Salts of Mercury. 207 



weight : in the former experiment, therefore, about one-tenth 

 of the bipersulphate, and in the latter rather less, remained 

 undecomposed. 



Having some reason to suppose that the compounds of 

 carbonic acid and mercury had not been sufficiently examined, 

 I collected all the evidence on the subject, which I have been 

 able to obtain from the numerous authors whom I have con- 

 sulted. Dr. Thomson {System, vol. ii. p. 658.) says; "Car- 

 bonic acid does not attack mercury, but it may be combined 

 with its oxide by pouring an alkaline carbonate into nitrate 

 of mercury. The precipitate in that case is a white powder, 

 composed according to Bergman of 



Mercury 90-9 



Oxygen and acid 9*1 



100-0 

 " Supposing the carbonate a compound of 1 atom carbonic 

 acid + 1 atom peroxide of mercury, it will consist of 



Carbonic acid 9'24" 



Peroxide 90-76 



100-00." 

 It must however be very evident that the salt obtained by 

 Bergman was not a percarbonate so constituted ; and pro- 

 bably it was not a percarbonate at all ; for 90*9 of mercury 

 require nearly 7*3 of oxygen for conversion into peroxide, and 

 consequently there is left only 1-8 for carbonic acid: if we 

 suppose it a protocarbonate, it must consist of about 90-5 prot- 

 oxide and 9-5 carbonic acid ; but for reasons, which I shall 

 presently state, I am inclined to believe that it contained no 

 carbonic acid whatever. 



In his Attempt &c. (vol. ii. p. 397.) Dr. Thomson does not 

 mention any percarbonate of mercury; but he informs us that 

 he obtained a white protocarbonate of mercury, by adding car- 

 bonate of soda to a solution of nitrate of mercury; the preci- 

 pitate lost 14-44. per cent, by solution in nitric a'citi, and Dr. 

 Thomson considers it, thoretbre, as a sesquiprotocarbonate of 

 mercury, composed of 



One atom and a half of carbonic acid 33 or 13-7 

 One atom of protoxide of mercury 208 86-3 



241 100-0 

 Although, as already mentioned, I have referred to many 

 chemical writers, for evidence as to the existence and com- 

 position of protocarbonate of mercury, yet except what 1 liave 

 (|uoted lioni Dr. Thomson, my researches have been attended 



with 



