210 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



of potash. Then, to get the percentage of iron in the ore, the 



following simple calculation will suffice: = x. Here 



x n 



m and n are the quantities of permanganate solution used 



respectively for the ore and the wire, and x is the value 



sought. The method gives remarkably accurate results, even 



in the hands of beginners. 21 A, May, 410. 



TO DETECT LEAD IX THE TIN LINING OF VESSELS. 



The following simple test may be found of great service 

 where it is desired to determine the presence of lead in ves- 

 sels used for canning fruit, etc. M. Fordos directs that a 

 carefully cleansed portion of the lining should be touched 

 with a drop of nitric acid, whereby both metals (if present) 

 are oxidized, the tin to stannic acid and the lead to nitrate 

 of lead. By slowly heating the acid will be driven off, when 

 the spot is to be touched with a drop of solution of iodide of 

 potassium. If lead is present the spot will turn yellow by 

 the formation of iodide of lead. The iodide has no action 

 upon tin. 6 B, XII., 1875. 



UTILIZATION OF THE PYRITE DEPOSITS OF THE BLUE EIDGE. 



Professor T. Sterry Hunt, in a recent communication to 

 the ISTew York World, reiterates the views upon this subject 

 which he advanced some two years ago at the Portland 

 meeting of the American Association. He then proposed to 

 utilize the pyrite deposits of the Blue Ridge as a source of 

 sulphuric acid, with which to convert into fertilizers the 

 phosphates of South Carolina on a large scale. Certain 

 objections having been made to this proposition upon eco- 

 nomical grounds, Professor Hunt reviews this side of the ques- 

 tion, and places it in a very favorable light. He argues that 

 with easily accessible beds of a high grade of pyrite or sul- 

 phur ore, like that of Spain, we might compete successfully 

 with Sicilian sulphur, even if this were free from duty. Of 

 this pyrite, which contains a small percentage of copper, 

 Great Britain imports and consumes about 400,000 tons an- 

 nually. The acid from this ore serves for the greater part 

 of her soda and fertilizer manufacture; and having thus uti- 

 lized the sulphur, she extracts from the residue by solution 

 several thousand tons of copper, leaving behind a nearly pure 



