1814.] Contributions to the Chemical Knoivledge of Mavganese. 413 



Article II. 



Contributions to the Chemical Knowledge of Manganese.* 



By Dr. Jchn. 



(Continued frojnyo], ii. p. 271.) 

 ACTION OF NITRIC ACID ON MANGANESE. 



a. On the Metal. 



Nitric acid when moderately concentrated, readily dissolves 

 mantranese with the evolution of considerable iieat, and the escape 

 of nitrous gas. The solution is colourless. It exhibits the same 

 properties as the solution of the white oxide in the same acid, of 

 which 1 shall speak immediately. 



By long continued evaporation the nitric acid is completely de- 

 coijiposed ; nitrous gas makes its escape, and the manganese 

 remains in the state of a black oxide. Tiiis experiment enabled 

 me to determine the quantity of oxygen present in the black oxide 

 of manganese. 



b. On the imperfect Oxide. 



Both the green oxide and the white carbonate dissolve with great 

 facility in nitric acid. Of all tlie crystallizable salts of manganese, 

 this is the most difficult to bring to the state of regular crystals. 

 Most chemists indeed doubt the possibility of obtaining such crys- 

 tals; but 1 have been fortunate enough to succeed in the following 

 manner. I evaporated a ncucral solution of this salt in a porcelain 

 vessel as far as possible, without dccompcising the acid, and allowed 

 it to cool rapidly. The whole solution concreted into a solid mass. 

 I mixed it with a very little v.'ater, heated it rapidly, then covered 

 up the vessel, and suii'ered it to cool at the temperature of 5'.)" 

 Fahrenheit. After an ititerval of some days, 1 found crystals at the 

 bottom of this solution, which possessed the following ))roperties. 



They have the form of priimaiic needles, v/hich running parallel 

 to the bottom of tiie vessel, stretcli from the one side to the other. 

 The faces of the crystals are channelled lengthwise. Tb.ey have a 

 white colour, are semi-transparent, and have a sharp bitterish taste. 



When exposed to the air, they deliquesce still more speedily 

 than muriate of manganese. They cannot endure a hiuh tcnj- 

 peraturi^ ; but melt in the twinkling of an eye, and arc completely 

 decompos'^d. 



They di'-^olvc in alcohol, and the solution gives to combustible 

 bodies dipt in it, liie property of burning with a green coloured 

 flame. 



• TransIaJrd from C>lil en's .loiirnni fur die Chccnte iind Phyfik. Viprlcrlmnd. 

 Sid. LSfi. N'.l linviiic li'-^ii :il)lc lo liiid room forsn liui^a tiiiic fiir lllfi iiisiTii'in of 

 iliis |ri|)<r, wv have (liuught il bciicr to deia^ suini; of our oilier [jajirrt.lliuu ilil'c'r 



h Ioiii;<T. — 'J'. 



