•20-2 Mixter— Acidic Oivi<l<s irlth Sodium Oxide. 



A k i . X X I II. — Seventh Paper on the Heat of Combination of 

 Acidic Oxides with Sodium Oxide; by W. G. Mixter. 



[Contritmtions from the Sheffield Chemical Laboratory of Yale University. | 



Tui'. heat oit'ects of the reactions of the heavy metals of the 

 first group and their oxides with the oxides of sodium have 

 been studied. Large errors in the experimental work were 

 unavoidable. The results, however, show that the higher 

 oxides of copper, silver and gold combine with sodium oxide 

 with considerable heat effect to form compounds which are 

 stable at high temperatures. 



Copper in the form of a powder burned poorly in sodium 

 peroxide. The oxide, because it was more finely divided than 

 the metal used, answered better. The reaction between the 

 oxide and the sodium peroxide may have been incomplete and 

 the result low. The cupric oxide for the two following tests 

 was prepared by heating basic copper carbonate to 500°. It 

 was in the form of a bulky powder. 



Experiment 1. — Cupric oxide 5 - 025, sulphur 1*000, sodium 

 peroxide 16 grams. Thermal result for 1 gram of cupric 

 oxide, 130 c . 



Experiment 2. — Cupric oxide 4 - 93, sulphur 1-000, sodium 

 peroxide 13 grams. Thermal result for 1 gram of cupric 

 oxide, 124 c . 



The fusions were good, dark green, and left when treated 

 with water a black residue which set free chlorine from hydro- 

 chloric acid, showing that a peroxide of copper was present. 

 The mean of the thermal results is 10,110 c for one gram mole- 

 cule of cupric oxide. Assuming that theCuO was all oxidized 

 to Cu0 2 and adding 19,400° for the heat required to reduce 

 Na 2 2 to Na 2 and O, we have for the heat effect of 



CuO + O + JSTa 2 = 29,500 c . 



Since the fusions were green it is evident that a compound of 

 a copper oxide and sodium oxide was formed. 



Silver, 



Silver in the form of fine powder was prepared by pre- 

 cipitating the metal by copper from a solution of the nitrate, 

 washing it with water and ammonia and drying. The follow- 

 ing determinations were made : 



