346 



partly by the oxygen of the air. The sulphate of manganese 

 may be readily dissolved in pure water, and will yield a white 

 prussiate of manganese with a solution of prussiate of potash. 

 These experiments may be made on a very minute scale, where 

 the object is merely to ascertain the presence of manganese, 

 as in ores of iron, soils, &c. ; when a slip of platina foil, glass, 

 or porcelain, &c., may be used. Where, however, it may be 

 desirable to obtain the pure salts from the sulphate of manga- 

 nese, larger quantities of the common oxide of manganese 

 must, of course, be employed. The presence of iron in the 

 common oxide will not interfere with the results, unless under 

 extraordinary circumstances. By this method the author has 

 discovered manganese in a large number of iron ores, as the 

 clay iron ores from Arigna, Merthyr Tydvil, America; the 

 Elba iron ores and specular ores from other localities; the mag- 

 netic iron ores from Arendahl, Norway ; also in the chromates 

 of iron from North America and the Shetland Islands, kindly 

 furnished by Dr. Scouler. In several of these ores, manga- 

 nese, it is believed, had not previously been detected. 



The Professor has also detected manganese in a number 

 of soils, as in those from the counties of Cork and Kilkenny, 

 and from near Dungannon. 



The use of the sulphate of manganese is gradually extend- 

 ing. Already it affords a beautiful brown colour in dyeing 

 and calico printing, and more recently it has been used in me- 

 dicine as an emetic ; and by no known method can it be so 

 readily obtained, in such a pure state, as by the use of man- 

 ganese and sulphur. 



The fine brown durable pigment of manganese, alike ap- 

 plicable, it is believed, to the commonest purposes and the 

 highest works of art, may also be readily procured by the me- 

 thod recommended. 



Professor Davy noticed an experiment he had made, which 

 seems to prove the delicacy of the test. He mixed Saxon 

 manganese, sulphur, and fine siliceous sand, in the proportions, 



