CHEMICAL SCIENCE. 185 



the sea-water mechanically retained about it. As this will occupy 

 some hours, the time may be employed by women and children in 

 trimming the stalks of the tangle (Laminaria diqitata) of leaves and 

 roots, and arranging them in readiness for the cutter. The whole 

 of the remainder may then be transferred into old hogsheads, in a 

 sheltered spot near the beach, and allowed to ferment. The succeed- 

 ing operations have been described. A quantity of the liquid is now 

 assumed to have been collected, to which is added commercial hydro- 

 chloric acid, until a very marked acid reaction is obtained; a solution 

 of oi'dinary chlorinated lime is then added to disengage the iodine, 

 taking especial care not to use an excess. A very little practice will 

 decide the quantity necessary, as the brown color of the liquid will 

 increase up to a certain point, and the smallest addition of chlorine, 

 when this has been attained, will diminish its intensity. Having thus 

 liberated the iodine, it is precipitated \vith the prepared starch and lead 

 diffused through water, continuing its addition until it is no longer 

 rendered blue by the iodine. The remainder of the process consists 

 in decanting the fluid portion, and straining the residuum, which, 

 when dry, will be immediately available to the iodine manufacturer, 

 and from which the iodide of potassium may be formed by the addi- 

 tion of sulphuret of potassium, or other appropriate means. The 

 fluid portion, being rich in potash, soda, and magnesian salts, will 

 form a most important contribution to the liquid manure tank, or may 

 be thrown over the compost of the farm-yard, with the additional 

 advantage of fixing the ammonia through its excess of hydrochloric 

 acid. The tissues of the sea-weeds remaining after the extraction of 

 the liquor can, when dry, be profitably used as fuel, and from the 

 ashes various salts may be extracted by lixiviation. London Chemi- 

 cal Gazette, July 1. 



We see no reason why this discovery may not be immediately 

 turned to a practical account in this country, as it doubtless will 

 be in Europe. The plants referred to occur in considerable abun- 

 dance upon the coast of the United States, one of the species be- 

 ing generally known under the name of the Devil's apron. Ed- 

 itors. 



NEW TEST FOR IODINE. 



MR. CHARLES WATT communicates to the London Chemist, for 

 January, a new test for the detection of iodine. He says, " to test for 

 the presence of iodine it will be sufficient to fuse a small piece of 

 chloride of zinc in a test-tube, having added a small quantity of man- 

 ganese, and to drop the substance we wish to examine into it, when, 

 if an iodide be present, iodine will be rendered evident by the color of 

 its vapor, or by its action on a piece of paper dipped in starch. So 

 delicate is this method of testing the presence of iodine, that, by add- 

 ing one drop of a solution of iodide of potassium, containing one grain 

 in an ounce, I could, by the color of the vapor, easily recognize the 

 presence of iodine." 



16* 



