Dr. Stenhouse on the Salts of Peroxide of Iron. 199 



Komenate of Silver. 



Komenic acid forms two silver salts, both of which have 

 been examined by Professor Liebig. 



The monobasic salt, which is a white floccqlent precipitate, 

 is made by adding komenic acid to a solution of nitrate of 

 silver. 



I. 02395grm. of salt gave 0*590 of silver = 43*64 per cent. 

 II. 0-4715 0*103 .., =a 43*98 ... 



The calculated number is 43*93, and the formula of the 

 salt XO AgO + aq. 



The yellow salt is formed by adding komenate of ammonia 

 to nitrate of silver. 



I. 0*313 grm. gave 0*1825 silver = 62*62 per cent, oxide, 

 II. 0*558 ... 0*325 ... = 62*46 



The calculated number is 62*48, with which I need scarcely 

 add that Professor Liebig's results approach very closely, 



XXX. 07i the Reduction of the Salts of Peroxide of Iron by 

 means of Vegetable Substances. By John Stenhouse, 

 Ph.D."^ 

 I" N the course of some experiments I had recently occasion 

 ■■■ to observe that some of the most common vegetable sub- 

 stances reduce the persalts of iron with very great facility. A 

 quantity of common meadow grass was immersed in a tole- 

 rably dilute cold solution of persulphate of iron. In the 

 course of half an hour, when tested with red prussiate of pot- 

 ash, the liquid gave a deep blue precipitate, indicating the 

 formation of a considerable quantity of protosulphate of iron. 

 After three days the solution was again tested, when the iron 

 was found to have been completely reduced to the state of 

 protoxide. Several other kinds or green vegetable matters, 

 such as twigs of trees and shrubs, produced similar results ; 

 as did meadow-hay, chips of wood and sawdust. Peat and 

 wood charcoal, of all the substances which I tried, appeared 

 to be those which effected the reduction of the persulphate with 

 the greatest rapidity. A solution was completely decomposed 

 by either of them in less than twenty-four hours; but with 

 the assistance of heat the reduction was effected in an hour 

 or two. Sugar, starch, gum, spirits of wine, oil of turpentine 

 and pieces of paper, though they produced no effect in the 

 cold, at a boiling temperature also caused a partial reduction 

 of the salt, The substances previously enumerated operated 

 exactly on solutions of the perchloride of iron as on those of 

 the persulphate. 



* Communicated by the Chemical Society; having been read April J, 

 1844. 



