Mr, R. Phillips on the Oxides q/' Manganese. 281 



monly made their appearance in this vicinity. Much might 

 be said upon this very interesting subject, and it is probable 

 we may recur to it at some future opportunity. 



Carlisle. August 28, 1829. 



XLII. On the Oxides of Manganese; in a Letter addressed 

 to Edward Turner, M.D. F.R.S. E., and Prof essor of Che- 

 mistry in the University of London. By R. Phillips, F.R.S. 

 L. 4' L. Sfc. 



My dear Sir, Birmingham, Sept. 1, 1829. 



f READILY subscribe to the opinion expressed in your 

 -^ letter to me, that " the temperate discussion of scientific 

 subjects rarely fails to advance the interests of science ;" and 

 I trust we shall also eventually agree that our correspondence 

 respecting the oxides of manganese, will form no exception to 

 the observation. 



In the first place, I am anxious to explain my reasons for 

 having doubted the accuracy of your analysis of the Ihlefeld 

 manganite. Some time after I had given you a specimen of 

 the Warwickshire ore of manganese, you informed me by let- 

 ter that it was manganite. Regarding this as a pi'ivate com- 

 munication, and more especially as I found that your analysis 

 differed from mine, I did not feel at liberty to publish it, al- 

 though I did not hesitate to adopt some of the statements which 

 it contained, as to the specific gravity and haidness of the mi- 

 neral in question. 



Admitting, nevertheless, the correctness of your opinion, 

 that the Warwick oxide was similar to the Ihlefeld ore, which 

 you had previously analysed and published an account of, and 

 finding from repealed experiments, that the former was not 

 deutoxide as you had stated the latter to be, I could hardly 

 avoid the inference that you had mistaken the nature of both. 



I have now, however, great pleasure in admitting the accu- 

 racy of your analysis of the Ihlefeld ore; I exposed 100 grains, 

 of the fragments which you sent me, to a red heat in a coated 

 glass retort, adapting to it, as in my former experiments, a 

 vessel accurately weighed to receive the water; the weight of 

 this was 10"4' grains, exceeding only by 0'3 of a grain the 

 quantity which you obtained from it; this excess was ))iobably 

 hygrometric moisture, for I did not dry the ore previously to 

 heating it in the retort; no oxygen gas was evolved, and as at 

 the temperature employed I have uniformly found deutoxide 

 of manganese remaining in the retort, I repeat what I have 

 already stated, that I have now no doubt of the perfect exact- 



N.S. Vol. 6. No. 34. Oct. 1829. 2 O ness 



