Irifiifficieiicy cfthe Methods offeparat'ing Phofphortij niid Mangsrtefe front Iron. i^f 



1 repeated this procefs on the fteels treated in this memoir, and did not difcover the leaft 

 trace of phofphate of iron, though they would have afforde.l ccnfidernble quantities by the 

 method I haie before propofed. This juftifies the afTertion that Bergman did not find this 

 fubltance in the different irons he analyfed, becaufe his method was infulEcient. 



I prove its infufficicncy as follows: — Iron and phofphorus united together, and brought 

 into contact with acidulated water, both tend to unite with oxygeiie by virtue of a pre- 

 difpofing attraclion between the acid which is added, and that which is formed, towards the 

 oxide of iron, whence the refult is fulphate and phofphate of iron. 



This laft is infoluble in water ; but it has an affinity for acids, by virtue of which it com- 

 bines, and becomes foluble in water. This affinity of the phofphate of iron for acids is 

 fuificient to impede and even fufpend the folution of new quantities of iron j fo that it 

 is not without difficulty, and after a length of time, that the phofphate of iron can be com- 

 pletely feparated from the fulphuric acid by means of metallic iron. 



It happens therefore in every cafe when iron or fteel which contains phofphorus is 

 dillblved in an acid, that the acid divides itfelf into two parts, one of which unites 

 with the oxide of pure iron, and the other with the phofphate of iron as it is formed ; and' 

 tliat when the acid is faturated by the oxide of iron and the phofphate of iron, the folutioa. 

 is almoft totally (lopped, though the liquor reddens blue vegetable colours. It may be 

 hence inferred, that the fulphuric acid, united with the phofphate of iron, no longer exerts 

 an equal power on the oxide of iron ; and that the metal does not decompofe the water, nor 

 unite to the oxygene of this fubftance but by its own peculiar force, which occafions a re- 

 tardation or even a complete fufpenfion of the folution. Now, if in fuch a folution the 

 phofphate of iron fhould be fmall in quantity, no fign of this metallic fait will appear, even 

 by the addition of a great quantity of water : and this is what happens in the procefs of Berg- 

 man ; whereas, by adding an alkaline carbonate to this folution until it ceafes to effervefcc, 

 tlie alkali unites with the fulphuric acid ; and the phofphate of iron, whatever may be its 

 quantity, falls down iu the form of a white powder. 



SECTION IX. 



Refli^ians on the Inftifficiency of the Methods hitherto propofed to difcover and feparate Mangamfi 



from Iron. 



BERGMAN is the firft who found manganefe in iron ; and almofl; every kind of iron 

 wliich he examined afforded quantities more or lefs confiderable. The maximum of this 

 quantity in fteel, according to this chemifl:, amounts to 0,3,0, and the minimum to 0,005, *' 

 latitude extremely great, and which appears fcarcely probable, as we fliall proceed to (hew. 



In order to dete£l manganefe in iron or fteel, the profcffor of Upfal propofcs two methods. 

 The (irft, having for its objeft to afcertain the prefencc of this metal, and being fpeedy, 

 cheap, and eafy to be performed, may be called explorative. It confifts in throwing into 

 five parts of fufed nitrate of pot-afh, one part of lilings of iron or (Ice), and to bring the 

 mafs into (Irong fufion after the detonation has taken place. If the crucible when cold" 

 exhibits towards its fuperior edge a vitreous circle of a grecnifli blue colour, it is, according 

 to him, a furc fign of the cxKlencc of niaii^iiucfc in the iron. Tlie otlicr method may be 



called. 



