180 Mr. Way on a Spathic Carbonate of Iron. 



chloric acid appears to act upon it with more energy than 

 either sulphuric or nitric acid. 



When analysed, the mineral was found to contain carbonic 

 acid, protoxide and peroxide of iron, lime and water. 



In order to obtain it as homogeneous as possible for quanti- 

 tative analysis, considerable portions of the mineral, which is 

 not harder than marble, were reduced to powder and well- 

 mixed. 



The results of two analyses subjoined, however, show that 

 its composition is not quite uniform. 



101-49 100-69 101-08 



The excess in the analyses appears to be due to an imper- 

 fect mixture of the different parts of the mineral, several por- 

 tions having been taken for the various operations. 



The water is as nearly as possible in the proportion to 

 form protohydrate of the peroxide (Fe20g+ HO), and there is 

 little doubt exists in that condition. 



The composition of the mineral may therefore be thus ex- 

 pressed : — 



Carbonate of protoxide of iron . . 83*60 



Carbonate of lime 7-47 



Hydrated peroxide of iron . . . . 10*01 



101 '08 



In examining the composition of this substance, considered 

 as a variety of the spathic carbonate of iron, the first pecu- 

 liarity worthy of attention is the absence of manganese. 



It would appear from all recorded analyses of the spathic 

 carbonate of iron, and also of carbonate of iron as existing in 

 clay- iron-stone, that manganese is a usual ingredient of both 

 varieties. Dr. Thomson of Glasgow describes, in his ' Out- 

 lines of Mineralogy,' a brown mineral under the name of 

 " Hydrous Carbonate of Iron," which appears from the ana- 

 lysis he supplies to be of similar constitution to that under 

 notice, — consisting of carbonate of the protoxide of iron with 

 hydrated peroxide of iron, but differing in containing so much 

 as 4*75 per cent, of protoxide of manganese. 



In four out of eight analyses by Dr. Colquhoun of clay- 

 iron-stone from the coal beds in the neighbourhood of Glas- 

 gow, given in the same work, manganese is mentioned, al- 



