76 InteUigoice and Miscellaneous Articles. 



Trithionic S^ 0\ sulphhyposulphuric acid of Langlois. 



Tetrathionic S'' O*, bisulphated hyposulphuric acid, discovered by 

 Fordos and Gelis in 1842. 



Pentathionic S^ 0\ the acid wliich is the subject of the present 

 memoir. 



The pentathionic acid in the free state greatly resembles the other 

 acids of the series. The solution is not rendered turbid by acids ; it 

 does not absorb iodine, and it forms soluble salts with the alkaline 

 and earthy oxides. These characters prevent this acid from being 

 confounded ^ith hyposulphurous acid. The pentathionate of barytes 

 was most particularly examined ; it may be obtained combined with 

 one equivalent of alcohol or two equivalents of water. Its formula 

 in the state of hydrate is S' 0\ BaO, 2H0 ; the hydrate is very 

 alterable ; the alcoholic compound keeps better. 



The spontaneous decomposition of the pentathionate of barytes is 

 extremely curious ; it may, by losing sulphur, become successively 

 tetrathionate and then trithionate. 



Sometimes the deposit of sulphur is accompanied with sulphate of 

 barytes, and in this case the solution acquires the smell of sulphu- 

 rous acid. These products, which are formed in larger quantity as 

 the temperature is higher, are the results of the ultimate decompo- 

 sition of the trithionate, 



S' 0% BaO = S03, BaO + S02 + S. 

 These decompositions, which give rise to many products, and 

 which continue during the whole time of the preparation, render the 

 procuring of the pentathionic acid extremely difficult, and serve to 

 explain all the various results which the reaction of the chlorides of 

 sulphur may occasion in the aqueous solution of sulphurous acid. — 

 Comptes Rciidus, Novembre 1847. 



ON SOME PROPERTIES OF CARBON. BY M. LAZOWSKI. 



The properties of carbon are numerous ; they have been partly 

 studied, but every day produces new facts : when it is in a state of 

 ignition, it possesses some very remarkable properties. 



When a piece of ignited charcoal, which is very clean and free 

 from ash, is immersed into a solution of a metalHc salt, it reduces 

 the metallic salt which is contained in it, and the metal itself is de- 

 posited with all its natural brilliancy on the piece of charcoal. Thus 

 the salts of tin, copper, platina, palladium, mercury, silver and gold, 

 &c. furnish most brilliant deposits. 



M. Lazowski has remarked, he says, that when the salts are too 

 acid or too much concentrated, no effect is produced. The dilute 

 solutions of the salts of copper often yield, by covering the charcoal, 

 the most varied shades of colour, from the finest azure blue to that of 

 metallic copper. The parts of the charcoal upon which certain me- 

 tals are deposited in preference, are the extremities ; whilst other 

 metals cover equally all the surface of the reducing body ; at other 

 times, and this occurs with the protochloride of tin, the metal ap- 



