On the Purification of Salts of Manganese from Iron. 519 



solubility of the Leguminosae in water, whilst the vegetable 

 fibrin of the Cereals is insoluble therein. There is therefore 

 ground for supposing that the phosphates are also bibasic in 

 the Leguminosae as well as in the Cereals ; the third atom of 

 the base would be consequently combined with the vegetable 

 casein, and the tribasic phosphate be formed during the in- 

 cineration. 



The great quantity of sulphuric acid (from 3"5 to '^•Q per 

 cent.) contained in the ashes of peas is remarkable in com- 

 parison to that of other seeds : in the ashes of beans it amounts 

 to 2 per cent., in the ashes of wheat and rye to only 0'5 per 

 cent., and is frequently altogether wanting. It is probable 

 that the cause arises from the small quantity of phosphoric 

 acid present, whilst the sulphur of the nitrogenous ingredients 

 is more easily retained as sulphuric acid by the alkaline bases 

 during the incineration. If fresh-prepared ashes from seed 

 containing tribasic phosphates are exposed to the air, they 

 take up carbonic acid. This is the reason why Boussingault* 

 found in the ashes of horse-beans one per cent., and in that 

 of the common beans 3*3 per cent, of carbonic acid. 



Upon comparing the ashes of the wood of the apple-tree 

 with that of the mistletoe growing from it, the difference in 

 the quantity of potash and phosphoric acid contained in each 

 is immediately evident: for whilst the ashes of the apple-tree 

 wood contain only 19 per cent, of potash and 4- per cent, of 

 phosphoric acid, we find that the ashes of the wood of the 

 mistletoe contain double the quantity of potash and five times 

 the quantity of phosphoric acid. 



The mistletoe therefore appears to perform upon the tree 

 the same functions (as far as regards the inorganic ingre- 

 dients) as the fruit, in absorbing from the sap the phosphates. 

 This is no doubt the cause of the injury produced on trees by 

 parasitic plants. Further analytical investigations with this 

 and other parasites will show whether this can be considered 

 as a general law. 



LXXXII. On the Purification of the Soluble Salts of Man- 

 ganese from Iron. Bif Alexander Kemp-J-. 

 'I'^HE commercial oxide of manganese commonly contains 

 "■ several impurities, but invariably a quantity of iron. 

 The separation of this iron from the salts of manganese be- 

 comes a matter of some importance, and consequently a num- 

 ber of processes have been given by chemists at different times 

 for this purpose. 



* Economic Rurale, t. ii. p. 327. 



t Communicated by the Author. On a subject closely related to that of 

 this paper, see Phil. Mag. S. 1. vol. lix. p. 86. 



