264 Hillebrand and Schaller — Mercury 



air, the mineral loses a little water, begins to brown at 135°- 

 150°, and as the temperature rises becomes still darker and 

 yields more water, but gives no visible sublimate under 260° 

 even after several hours. Between 260° and 280° mercury 

 and calomel (not HgCL) sublime. When most of the calomel 

 has passed off the residue begins to grow lighter colored, then 

 yellowish and finally becomes nearly white. During the 

 expulsion of the calomel some gas (CI?) is evolved in minute 

 amount that sets free iodine from solution of potassium iodide. 

 On heating to 400° more of this active gas is evolved, but it is 

 soon followed or accompanied by one that destroys the color 

 of the free iodine (S0 9 ?). At 400°-420° appears a further 

 sublimate less volatile than the calomel. If the test is made 

 in a closed assay tube this last sublimate and the still unvola- 

 tilized residue may melt to a dark reddish liquid, which on 

 cooling solidifies with a yellowish and then white color. 

 Ammonia turns both sublimates black instantaneously, although 

 the later one often contains mercuric as well as mercurous. sul- 

 phate. Most of the nitrogen escapes in the elemental state dur- 

 ing the formation of the calomel, but not quite all. There is 

 not the least evidence of the formation of ammonia. If the 

 heating is carried out in vacuo the evolution of the active gas 

 is much more marked than at atmospheric pressure and if col- 

 lected by a pump is seen to be of the color of chlorine. Under 

 the vacuum this gas does not act on the mercury of the pump, 

 but fouls that in the collecting tube strongly under atmos- 

 pheric pressure. The scum on the mercury gives tests for 

 chlorine. This liberation of free chlorine was at first supposed 

 to indicate direct union of nitrogen and chlorine in the min- 

 eral, but since it is also given off on heating in vacuo a mix- 

 ture of the artificial compound NHg 2 Cl.a?H 2 with a sulphate 

 of mercury (3HgO. S0 3 in the test) it is evidently a secondary 

 reaction between one of the products of breaking up of the radical 

 S0 4 and vapor of calomel or of the still undecomposed chlo- 

 rine constituent of the mineral. 



Behavior toward liqxdd reagents. — Soluble in warm hydro- 

 chloric as well as nitric acid without deposition of calomel. 

 Also soluble in sodium sulphide and in ammonium bromide. 

 The latter liberates as ammonia for every one part of nitro- 

 gen derived from the mineral itself three parts from the 

 reagent. Fixed alkalies do not liberate ammonia. Hydrogen 

 sulphide blackens speedily, ammonia not at all. 



Additional data. — Several tests were made by decomposing 

 the mineral in vacuo under varying conditions of treatment 

 in order to get evidence as to the presence of either hydrogen 

 in addition to that which was afforded as water or of oxygen 

 other than that in the water and the SO, radical. For the 



