1821.] and on the Composition of its Oxides, 55 



deutoxide of iron, but rather darker. It is soluble in some acids. 

 Muriatic acid dissolves it when at about 42° Fahrenheit. It is 

 necessary that the muriatic acid should be very strong, and the 

 deutoxide of manganese added in small quantities at a time, in 

 order to avoid increasing the heat of the liquid. Thus a dark- 

 brown solution is obtained, which, in a temperature below 41° 

 Fahrenheit, may be kept a few days unaltered ; but when exposed 

 to the sunbeams, or to any increase of temperature, chlorine is 

 evolved, and muriate of protoxide formed. In those cases where 

 I succeeded in charging the concentrated muriatic acid with a 

 considerable quantity of oxide of manganese, the proportions 

 seemed to me to be such that when I destroyed the compound 

 by heat, I obtained chlorine and neutral muriate of protoxide : 

 the experiments, however, on which I found that opmion were 

 not very accurate. When the muriatic solution is poured into a 

 large quantity of water, a mixture of deuto^^ide and peroxide is 

 thrown down, and muriate of protoxide remains dissolved. The 

 muriatic solution of deutoxide, even when no chlorine can be 

 discovered by the smell, acts nearly in the same way as an 

 aqueous solution of chlorine, metals are instantly dissolved, and 

 an adequate portion of deutoxide brought to the state of protox- 

 ide. Tartaric acid, when thrown into such a solution, instantly 

 emits carbonic acid gas ; and sulphurous acid and sulphuretted 

 hydrogen, when in contact with it, instantly form sulphuric 

 acid. 



The sulphuric acid acts nearly in the same way as the muriatic 

 acid, and the sulphuric solution of deutoxide has the same 

 properties with respect to metals and vegetable substances as the 

 muriatic solution, which induced Mr. Giobert, about 30 years 

 ago, to beheve in the existence of an oxygenated sulphuric acid. 

 Sulphuric acid, when much diluted, decomposes the deutoxide 

 and forms peroxide and sulphate of protoxide. I never could 

 obtain a nitric solution of deutoxide, but always procured nitrate 

 of protoxide and peroxide. 



It is a curious fact that the existence of this deutoxide has 

 been very often denied, though it is of all the different oxides 

 of manganese, the only one which is easily obtained in its pure 

 state. As the quantity of oxygen found in this oxide seemed not 

 to agree with the rules laid down for the relation of the oxygen 

 of the different oxides, it was, in contradiction to all its proper- 

 ties, supposed to be a compound of two oxides ; viz. of the prot- 

 oxide, and a deutoxide which does not exist. This oxide is 

 formed by the combustion of the protoxide of manganese in the 

 oxygen of atmospheric air, as was observed by Scheele. When, 

 pure protoxide is heated in the air between the boiling point 

 of water and that of mercury, it suddenly begins to take fire, 

 and burns slowly with a reddish light. This on]y takes place 

 when the protoxide does not contain carbonic acid. The car- 

 bonate, when heated to the same temperature, and under the 



