Mixter — Acidic Oxides toith Sodium Oxide. 



205 



The mixture of gold, sulphur and peroxide fused and left 

 on cooling a compact mass. When the fusions were disin- 

 tegrated in water part of the sodium aurate hydrolyzed with 

 separation of auric hydroxide and at the same time the sodium 

 peroxide present reduced considerable gold. Hence the 

 metallic gold in the insoluble portions of the fusions should 

 not be deducted from the amount taken. In experiment 1 the 

 residue left by water was treated with hydrochloric acid to 

 remove auric hydroxide and the gold remaining was 2'7 grams. 

 In the second experiment, where less peroxide was used than 

 in the first, the gold from the fusion was only 0*8 gram. A 

 small amount of gold in the form of minute fused particles 

 was observed in the residues left by water in experiments 1 

 and 3. 



The wide differences in the results obtained are due, in part, 

 to variable but small amounts of gold not attacked and in 

 part to unavoidable small errors all of which affect the small 

 values for gold. The mean of the result is 77 c for one gram 

 of gold reacting with sodium peroxide. For two gram atoms 

 it is 77 c X 197-2 X 2 = 30,400 c . 



Auric Oxide. 



The attempt to make pure auric oxide for this investigation 

 led to a study of auric hydroxide.* It was found that the 

 hydroxide loses oxygen before all of the water is expelled. 

 The substance taken from the calorimetric work was prepara- 

 tion B described in the paper referred to. In composition it 

 corresponded closely to the formula Au 3 4 . Although it was 

 a mixture of auric oxide and metallic gold it will be considered 

 as auric oxide in the calculations and the following experi- 

 ments : 



6 



Auric oxide 



Sulphur 



Sodium peroxide 10- 



Observed heat . .. 



Heat due to S and Fe 



For one gram of Au 2 O s .. 



4-004 



grams 



3-811 grams 



1-000 





a 



1-000 " 



o- 





cc 



10- " 



6216° 







6206 c 



5320° 







5320° 



896 c 



886° 



224 c 







232° 



The mean, 228°, multiplied by M2-4:, the molecular weight 

 of auric oxide, gives 100,900° for the heat effect of 

 3Na„0 -f- Au 2 3 . The result is low since both fusions con- 

 tained a little metallic sold and correction is not made for the 



* Auric hydroxide formed on a gold anode, 

 ide when heated. J. Am. Chem., xxxiii, 688 



Deportment of auric hydrox- 



