178 Miscellaiieomi Jnteliigence. 



to the sun. When heated with muriatic acid it is entirely decom- 

 posed and reduced to prot-oxide, which combines v/ith the acid. 

 AlcaH is not required for the formation of roanganesic acid ; 

 hydrated per-oxide of lead, sulphate of manganese, and sulphuric 

 acid, will produce it on mixture, but it is then difficult to free it 

 from sulphuric acid. Also, when chlorine prepared from the 

 per-oxide of manganese is passed into a solution of potash, the 

 chlorine volatilizes a small portion of per-oxide of manganese, 

 and converts it, when acted upon by the potash, into manganesic 

 acid, which combines with the alcali. Again, when chlorine was 

 passed through water containing per-oxide of manganese, and 

 potash added to this saturated water, after separation from the 

 excess of oxide, a small quantity of deut-oxide was precipitated, 

 and the solution became red. 



All the oxides of metals seem either to form soluble com- 

 pounds of a red colour with the manganesic acid, or to decom- 

 pose it, in which case the oxide added is converted into per- 

 oxide, and the acid into deut-oxide. The brown powder thus 

 obtained by lead is soluble in cold nitric acid with a brown 

 colour, when heated it turns red. Hence the brown powder is a 

 chemical compound of the per-oxide of lead, (acting as an acid,) 

 and the deut-oxide of manganese, for neither of these bodies 

 alone are soluble in nitric acid : when heated to the temperature 

 of boiling water, the oxygen of the per-oxide goes to the man- 

 ganese, and converts it into manganesic acid. 



By igniting nitrate of barytes with oxide of manganese, and 

 washing the green powder thus obtained with boiling water, 

 a manganesite of barytes was obtained. It has a beautiful eme- 

 rald green colour, and when dry, is very little altered by the air. 

 The manganeseous acid was analyzed by adding to a certain 

 quantity of the green chamaeleon, nitrate of lead ; this threw down 

 the brown powder, which contained both the manganese and the 

 oxygen of the manganeseous acid, and prot-oxide of lead. This was 

 distilled with certain precautions with bi-sulphate of potash, and 

 the oxygen evolved estimated, it equalled 4.82 French duode- 

 cimal cubic inches, at a temperature of 10° centigrade, equal, 

 according to Biot, to 0.1303057 grammes, (1.7127 j>:r.). The 



