80 Intelligence and Miscellaneous Articles. 



are usually in the form of six-sided tables. This salt undergoes no 

 change by exposure to the air; at 212° it becomes opake but does 

 not effloresce ; it then becomes yellow in the light. When mode- 

 rately heated it loses 3 equivalents, or half its water of crystallization, 

 and the remaining 3 are expelled at a higher temperature, but it 

 becomes yellow and continues to smell ; at a still higher temperature 

 it fuses and loses much sulphurous acid. 



The barytic salt crystallizes in rhombic tables which are colourless 

 and brilliant. It dissolves slowly in water ; it loses all its water of 

 crystallization at a high temperature, becomes opake and begins to 

 decompose. It contains 3 equivalents of water. 



M. Wohler states that he shall hereafter consider the formation 

 and composition of this acid, as to whether it should be considered 

 to contain 1 equivalent of hyposulphuric acid or 2 equivalents of 

 sulphurous acid. The mode in which it is acted upon by water fa- 

 vours the latter view, and its action on selenious acid also supports it. 

 When it is employed alone it is not altered by it ; but by admixture 

 with b3'drochloric acid, the selenious acid is reduced. When the 

 acid is mixed with chloride of gold, there separate, after some time, 

 opianic acid and reduced gold in brilliant tables. — Ann. de Ch. et de 

 Phys., Octcbre 1844. 



ON SULPHOPIANIC ACID. 



M. Wohler gives this name to the acid produced by the action of 

 sulphuretted hydrogen on opianic acid. 



When sulphuretted hydrogen gas is passed into a boiling solution 

 of opianic acid, no visible action occurs; but if the temperature be con- 

 siderably reduced, the liquor loses its transparency, and a precipitate 

 resembling sulphur is formed, the quantity of which goes on increa- 

 sing. By these means all the opianic acid is converted into this 

 new compound, but the change occupies several days. If the mix- 

 ture be heated to ebullition, the yellow precipitate disappears, and is 

 converted into a liquid of the same colour, which soon falls to the 

 bottom of the vessel, where it becomes solid on cooling. 



Sulphopianic acid thus obtained is an amorphous transparent mass 

 of a sulphur-yellow colour, which liquefies at 212°. If it be more 

 strongly heated, it decomposes, emitting a yellowish vapour which 

 condenses in fine crystalline needles ; these burn with flame and 

 evolve sulphurous acid; they are insoluble in water, but dissolve 

 readily in alcohol, to which they impart a yellow colour. If the acid 

 has been fused previously to being dissolved in the alcohol, an amor- 

 phous transparent mass merely is obtained by spontaneous evapora- 

 tion ; but if in the preparation of the acid the heat has been so 

 managed as to prevent its fusion, it is then obtained in the state of 

 small transparent crystals, which when collected have a yellow colour. 

 This acid therefore undergoes by fusion a change analogous to that 

 which opianic acid suff^ers under similar circumstances. Concentrated 

 sulphuric dissolves it and becomes yellow, and when heated of a 

 deep purple. Chlorine and the alkaline hypochlorites oxidize the 

 sulphur which it contains slowly and imperfectly; the alkalies dis- 



