222 Dr Colqiihoun on the Argillaceous Ore of Iron. 



which mineralogists might have deduced with certainty its 

 peculiar chemical constitution. It is possible, however, that 

 a discovery so interesting may have escaped the notice of con- 

 temporary and succeeding chemists, owing to the circumstance, 

 that in Richter's publication, entitled Analyse der Eisensteine 

 zu Bielschomitz in Oberschlesien, nebst Bestimmung des quan- 

 titativen Verhdltnisses ihrer Bestandtheile, * his main object 

 was not to establish the existence of a new and important mi- 

 neral, but to describe a novel and very unsatisfactory method 

 of determining the proportions of oxide of iron and alumina 

 which might exist in any solution. He precipitated both si- 

 multaneously, weighed and calcined the precipitate, then by- 

 computation from the loss of weight sustained in the calcina- 

 tion, he eliminated the respective amount of each substance 

 by his peculiar system of stoechiometric calculation. En- 

 grossed with the investigation of this useless novelty, Richter 

 seems to have entirely lost sight of the interesting and impor- 

 tant nature of the results of his analyses ; and other chemists, 

 in their just dishke to the general object of his memoir, im- 

 properly overlooked some of the truly valuable details which 

 it furnishes. From these, however, Dr Thomson must be 

 excepted ; he has quoted these analyses of Richter in his Si/s- 

 tem of Chemistry, and deduced from them the right conclu- 

 sions regarding the chemical constitution of the ore. -f- 



The specimens of the ore analyzed by Richter had been 

 procured from Bielschowitz in Upper Silesia. He denomi- 

 nates them, in general terms, Eisensteine, or Ironstones, but 

 it is evident from the details of his analyses that they must 

 have been the argillaceous carbonate of iron. He found the 

 same ingredients existing in all the specimens, though vari- 

 ously proportioned, and he ascertained them to be the black 

 oxide of iron, alumina, silica, traces of the oxide of manga- 

 nese, carbonic acid and water ; the last two ingredients 

 amounting from about 28 to about 32 per cent. He disco- 

 vered that none of them contained lime, and that, neverthe- 

 less, they effervesced strongly during solution in muriatic 

 acid. From the details which he gives it is apparent that he 



• Crell'a Chemische Annalen, 1796, i. 540. 

 t Sixth Edition, iii. 485. 



