82 MATER i A MEDIC A AND THERAPEUTICS. 



debility depends. Thus the iodide of iron is employed in 

 syphilis and scrofula ; the arseniate in chronic diseases of the 

 skin, liver, etc., with a gouty, rheumatic, or malarial taint ; the 

 phosphate in diseases of the hones, such as rickets ; and the 

 compound with quinine in malarial cachexia, where it may 

 rapidly restore the blood corpuscles. But all the preparations 

 of this group, and especially the last, are also used as ordinary 

 tonics, according to circumstances. 



The Solution of the Persulphate of Iron is introduced solely 

 as a source of several other preparations. Ferri Peroxidum 

 Humidum is the best form as an antidote to arsenic, the rationale 

 of which has been already explained. 



MANGANESIUM. Mn. MANGANESE. 



The only salt of this metal in the Pharmacopoeia 

 is the black oxide ; but permanganate of potash, 

 which is derived from it, is best discussed under this 

 head. 



Manganesii Oxidum NigYiim. Black Oxide 

 of Manganese. Mn0 2 . A heavy black powder. 



From Hanganesn Oxidum Nigrum is made : 



Potassse Permanganas. Permanganate of Potash. 

 KMn0 4 . 



Source. Made by (1) evaporating a mixture of Black 

 Oxide of Manganese, Chlorate of Potash, and Caustic 

 Potash in water, pulverising the residue, heating it to red- 

 ness, cooling and piilverising; then (2) boiling in Water, 

 neutralising with Diluted Sulphuric Acid, and e vaporati ng. 

 (1) 3Mn0 2 + KC10 3 + 6KHO = 3K 2 Mn0 4 + KC1 -f 

 3H 2 O ; a manganate being formed. (2) 3K 2 Mn0 4 -j- 

 2H 2 = 2KMn0 4 + 4KHO -f Mn0 2 ; the manganate 

 becoming permanganate by boiling. 



Characters. Dark purple, slender prisms, in- 

 odorous, with a sweet astringent taste, yielding an 

 intense purple solution when moistened. Solubility, 1 

 in 16 of water. Is very rapidly deoxydised in the pre- 

 sence of organic matter into hydrated peroxide of manga- 

 nese, losing its purple colour for a brown. 



Impurities. Sulphate of potash, and black oxide of 

 manganese ; detected by being less soluble in water, and 

 by volumetric test. 



Dose. 1 to 2 gr. 



