G. F. Becker—Solutions of Cinnabar, Gold, etc. 208 
perature. If mercuric sulphide is left in contact with cold sodic 
sulphydrate for twenty four hours, just a trace of mercury goes 
into solution. This is due to the spontaneous loss of hydrogen 
sulphide which the sulphydrate is well known:-to undergo. 
The absolute want of power of a preparation of sodic sulphy- 
drate to dissolve a trace of mercuric sulphide is perhaps the best 
known test of its freedom from the alkaline monosulphide. 
This test does not show the absence of polysulphides, however, 
for we have frequently found mercuric sulphide totally insolu- 
ble in solutions of sodic sulphydrate, which possessed a yellow 
color, and which were proved by analysis to contain an excess 
of sulphur. This corresponds to Barfoed’s observation. The 
occurrence of alkaline polysulphides in nature, excepting near 
the surface of the earth, seems so improbable, that I have under- 
taken no investigations of the conditions under which they dis- 
solve mercuric sulphide. 
Solubility of HgS in mixtures of Na’S and NaHS.—For the 
purpose of determining the character of solutions of mercuric sul- 
phide in mixtures of sodium sulphide and sulptydrate, clear 
solutions of mercuric sulphide in sodium sulphide and sodium 
hydrate were made, all the reagents being carefully prepared for 
the purpose, and sulphuretted hydrogen was passed through the 
solution until a large permanent precipitate of mercuric sulphide 
formed. The mass was then filtered, and of course the filtrate 
represented an absolutely saturated solution of mercuric sul- 
phide in a mixture of sodic sulphide and sulphydrate. A por- 
tion of this solution was analyzed. The remainder was treated 
further with hydrogen sulphide, the precipitation being arrested 
before the separation of mercuric sulphide was completed, and 
the second filtrate, representing a second saturated solution of 
the metallic sulphide in a mixture of alkaline sulphide and sul- 
phydrates, but one containing much less mercuric sulphide, was 
also analyzed. 
_ These analyses, which formed the conclusion ofa tedious series 
of experiments, show beyond any reasonable doubt that there 
18 a compound HeS, 4Na’S which is soluble in the presence of 
Na’S, H’S and which is decomposed by hydrogen sulphide in 
the presence of the sulphydfate by the reaction, 
HgS, 4Na’S + 4H°S=HeS + 4Na’S, HS. 
Conclusion from the experiments.—It appears from the above that 
there are at, least three double salts of the form HgS, nNa’S, 
where n may be either 1, 2 or 4 and, judging from the analogy 
of the potassium compounds, there is probably also a compound 
of this group where n is $. The possibility of acase where 7 is 
8 has also been adverted to. Thus mercuric sulphide readily 
enters into combination with sodic sulphide in various propor- 
