OF ARKANSAS. 



117 



The succession of the 

 rocks on the waters of 

 the Middle Fork of 

 White river, is exhibited 

 in the accompanying 

 diagram, in which the 

 position of the bed of 

 dark grey, pyritiferous 

 limestone is shown, in- 

 cluded in the shales at 

 the base of the section. 

 Several so-called " sul- 

 phur springs," rise 

 through the black bitu- 

 minous shales, at the bot- 

 tom of the sections, in 

 the central part of Wash- 

 ington county. The wa- 

 ter of one, which was ob- 

 tained from John May's 

 place, one mile south of 

 Favetteville, was found 

 by the application of chemical reagents, to contain, as its principal 

 constituents : 

 Sulphate of magnesia, (Epsom salts). 

 Sulphate of alumina, a trace. 

 Sulphate of iron, a trace. 

 Bi-carbonate of lime. 

 Bi-carbonate of magnesia. 

 This water will act as a mild laxative. 



County surveyor Ross informed me that there has been some difficulty 

 in running lines with the compass, in the valleys and along the spurs of 

 some of the hills, with what is considered the true variation in this part 

 of the State, of 8 deg. SO mm. The iron ores which I have seen on the 

 surface, viz., limonite ores and protocarbonate of iron, do not affect the 

 magnetic needle ; neither have ores of lead any influence on it : it is only 

 native iron, iron ores containing a combination of peroxide and protoxide, 

 in the proportion of about 69 per cent, of the former, and 31 of the latter, 

 and magnetic iron pyrites, containing about 40 per cent, of sulphur and 

 60 of iron, that attract the needle. Those localities will require, therefore, 



