Silver, and its Combinations with the Oxide of that Metal, 491 



cess given in the former part of this paper and reduced to a 

 fine powder, were acted upon by very dilute hydrochloric 

 acid and boiled ; this threw down chloride of silver, which 

 when well aggregated by the boiling was thrown upon a 

 double filter and carefully washed, and gave, after being dried 

 and heated to incipient fusion, 13*1 grains, equivalent to 10*5 

 grains of the oxide of silver. 



To the filtered solution a small quantity of alcohol was 

 added, and the whole boiled until a perfect deoxidation of the 

 chromic acid had taken place ; the alcohol was then evaporated 

 off, and the protoxide of chromium precipitated by a solution 

 of caustic ammonia added in slight excess; this after being 

 well washed, dried, and heated to full redness, weighed 7*2 

 grains, which are equivalent to 9*36 grains of chromic acid. 

 We have therefore the following proportions for the compo- 

 sition of this salt, corresponding as closely as we can expect 

 with the theoretical constitution of the bichromate of silver. 

 By Experiment. By Theory. Atoms. AtomicWeight. 

 Chromic acid 9*36 9*455 2 104 



Oxide of silver 10-59 10*545 1 116 



19*95 20-000 220. 



When the above salt is boiled in distilled water a part of 

 it is dissolved, and separates in beautiful micaceous crystals 

 of a very rich crimson colour as the solution cools, while at 

 the same time another part of the salt is resolved into chromic 

 acid and a very dark green crystalline chromate of silver, 

 crimson however by transmitted light, and yielding by tri- 

 turation a powder similar in colour to the precipitated chro- 

 mate. This after being well washed and dried was submitted 

 to exactly the same method of analysis as the bichromate of 

 silver, (as were also the two salts next mentioned,) and gave 

 from 2-1 grains. 



By Experiment. By Theory. Atoms. Atomic Weight. 

 Chromic acid -646 '65 1 52 



Oxide of silver 1*440 1-45 1 116 



2-086 2-10 16S 



The precipitated chromate, obtained by adding a solution 

 of the yellow chromate of potass to one of the nitrate of sil- 

 ver, yielded exactly the same results. 



The bichromate of silver is readily soluble in ammonia, 

 affording a clear pale yellow solution, which by exposure to 

 the atmosphere has a dark green pellicle or crust formed on its 

 surface, having a metallic lustre, and being of a rich claret 

 colour by transmitted light, giving however the same kind of 



3 R2 



