178 PROCEEDINGS OF THE AMERICAN ACADEMY 



I. 34.0554 grm. of a solution saturated at 20° gave 0.0346 grm. 



CaSO,. 

 II. 27.6386 grm. of a solution saturated at 20° gave 0.0267 grm. 

 CaSO,. 



The aqueous solution saturated at 20°, therefore, contained the 

 following percentages of the anhydrous salt : — 



I. II. 



0.54 0.57 



Argentic Tribrompyromucate^ AgC^BrgO,. — Argentic nitrate gives 

 even in tlie cold aqueous solution of the acid a crystalline precipitate 

 of the silver salt, which is sparingly soluble even in boiling water. It 

 may readily be prepared by precipitating a soluble salt of the acid 

 with argentic nitrate and washing with hot water. 



0.2977 grm. of the salt gave 0.1242 grm. AgBr. 



Calculated for AgCjBrjOj. Found. 



Ag 23.68 23.96 



Sodic Trihrompyromucate, NaC^Br^Oo . H.,0. — The sodium salt we 

 prepared by dissolving the acid in a dilute solution of sodic carbonate. 

 The salt was not very soluble in cold water, and crystallized, on cool- 

 ing the aqueous solution, in fine woolly needles, which contained one 

 molecule of water and slowly effloresced over sulphuric acid. 



I. 1.0434 grm. of the air-dried salt lost at 108° 0.0457 grm. R,0. 

 II. 1.1171 grm. of the air-dried salt lost at 112° 0.0531 grm. H^O. 



CaVulatcd for Found. 



NaCcBrsOj . HjO. I. II. 



HgO 4.63 4.38 4.76 



I. 0.5947 grm. of the anhydrous salt gave on ignition with H.^SO^ 

 0.1132 grm. Na.^SO,. 



II. 0.5036 grm. of the anhydrous salt gave on ignition with HgSO^ 



0.0987 grm. Na^SO,. 



Na 



Potassic Trihrompyromucate, \s.CSQr.^Op.\lf}. — The potassium salt 

 we prepared by neutralizing a dilute solution of potassic carbonate 

 with the acid. It was not very soluble in cold water, and crystallized, 



