HISTORY OF THE AMERICAN MENHADEN. 489 



tbo Asliley and Cooper Rivers and from Chisbolm's Island in Bull 

 Eiver, near Saint Helena Sound. The company owns Swan Island, sit- 

 uated in the Caribbean Sea, about 290 miles oiH Jamaica, and the phos- 

 phate of lime was obtained from that point until 180G or 18G7, when the 

 reopening of the south gave access to the Charleston beds. The 

 company of late has used a considerable quantity of the rock from 

 Navassa, a small island lying between Cuba and Santo Domingo, a red- 

 dish deposit, rich in phosphate of lime. This deposit is estimated to 

 contain on the average 72 per cent, of phosphate of lime, while the 

 brown deposit from Saint Helena Sound, technically known as " marsh- 

 rock," contains 60 per cent., and the yellow " land-rock," from the 

 vicinity of Chaileston, only 50. About 12,000 tons of this rock is used 

 annually in the Woods Holl establishment. Great piles of rock are 

 to be seen lying out of doors and under sheds, and at the time of 

 my visit it was estimated that there were seven or eight hundred tons 

 on hand. The only damage to which it is liable from exposure is 

 that it collects moisture and becomes more difficult to grind. In susch 

 cases it is piled in great heaps upon a brick floor, and roughly kiln- 

 dried by a fire of soft coal kindled under it. 



The sulphuric acid used is manufactured on the spot from Sicily sul- 

 phur, which is brought in vessels from Boston and direct from the Medi- 

 terranean. About 1,200 tons of sulphur are used annually, and not far 

 from 3,000 tons of sulphuric acid. The sulphuric acid used in manufac- 

 ture is brought up to a standard density indicated by CO on the Baume 

 hydrometer, a specific gravity of 1.7674. 



The buildings used in this branch of the business are nearly as exten- 

 sive as all the others. The three leaden tanks have a capacity of 

 185,000 cubic feet, the smaller containing 48,000 the others 2,000 and 

 6,500 respectively. 



In the early days of the business the sulphuric acid was brought 

 from Waltham, Mass., and New Haven, Conn., in carboys, but since 

 1866 it has been manufactured in Woods Holl at a large saving of ex- 

 pense. The Leopoldshall kainit, which averages about 12^ per cent, 

 potash, comes from the mines at Leopoldshall, in the Duchy of Anhalt, 

 near Stassfurt, in Germany. Its use is comparatively recent, until this 

 year it having been impracticable to obtain it in any considerable 

 quantity. At the time of my visit a Hamburg brig was discharging a 

 cargo at the wharf. Not far from 500 tons are used annually. It takes 

 the place of the coarse salt formerly used, a refuse product from the 

 gunpowder works at New Haven, Conn. 



The process of manufacture is sufficiently simple. The fish-scrap, on 

 its reception, is stored, after being mixed with about 3 per cent, of its 

 weight of kainite. This is a precaution necessary to prevent fermenta- 

 tion and putrefaction. Experiments are now in progress to test the 

 effect of a large mixture of kainite, which it is hoped will do away 

 entirely with this trouble. Common salt, as has been stated, was for- 

 merly used for this purpose. 



