524 Mr. T. Graham on the Absorption and 



Gold. 



1. A quantity of gold was precipitated from the assay cor- 

 nettes used below by means of oxalic acid. The gold weighed 

 93*3 grms., with a volume of 483 cub. centims., taking the spe- 

 cific gravity of the metal as 19*3 1. Exhausted at a red heat 

 without any further treatment, the reduced gold yielded 3'4 cub. 

 centims. of gas, which may therefore be supposed to be gas 

 usually present in gold reduced in the manner described. This 

 is 0*704 vol. of the gold. The occluded gas in precipitated gold 

 gave to analysis 



005 cub. centim. Oxygen. 

 1*50 „ „ Carbonic acid. 

 185 „ „ Carbonic oxide &c. 



^40 



2. Of the original cornettes of fine gold, from gold-assays 

 conducted several months before, 93*3 grms., having a volume 

 of 4*83 cub. centims., were submitted without any further treat- 

 ment to aspiration at a red heat. The gold gave up in the first 

 half hour 9*45 cub. centims. of gas, and in the second half hour 

 0*8 cub. centim., making together 10*25 cub. centims. Hence 

 1 volume of the gold cornettes appears to hold 2*12 volumes of 

 gas. This gas consisted of. 



6*70 cub. centims. Carbonic oxide. 



1-50 „ 

 1-58 „ 

 044 „ 

 0-03 „ 





Carbonic acid. 

 Hydrogen. 

 Nitrogen, 

 loss. 



10-25 



cornettes do not { 



ippea 



r ever to assume 



The 



gas as they first acquired in the assay muffle. It follows that 

 the weight of a gold cornette is increased about 2 parts in 

 10,000 by the weight of occluded gas. As the gold also re- 

 tains 7 or 8 parts of silver in 10,000, it follows that the ab- 

 solute quantity of gold in a cornette is less than the weight 

 of the cornette as indicated by the balance by 1 part in 1000. 

 This does not disprove the accuracy of the usual gold-assay, 

 which is always made in comparison with gold of known compo- 

 sition as a check, and is therefore relatively true. 



3. The same volume of gold cornettes, amounting to 4*83 

 cub. centims., heated again in carbonic oxide gas, gave up after- 

 wards 1*6 cub. centim. of occluded gas composed of 

 1*4 cub. centim. Carbonic oxide. 

 0*2 „ „ Carbonic acid. 



1-6 



