further Experments and Ohsetvations on Iodine. 367 



The eflfect produced by compounds of iodine, may be di- 

 stinguished from that produced by sulphurets or sulplmretted 

 !iydrogen by this circumstance, that solutions containing sul- 

 phurets or sulphuretted hydrogen, by being boiled with a little 

 muriatic acid, no longer tarnish the metal, whereas solution* 

 containing iodine still retain the power. 



4. Amongst a number of sea v^ecds that were obligingly given 

 me for examination, by Professor Viviani, of Genoa, the ashe« 

 of the following afforded slight indications of the presence of 

 iodine, 



Fucus cartilagineus. Fucus filamentosus. 



— : membranaceus. Ulvapavonia. 



rubens. linza. 



In the ashes of the corallines and sponges, I could discover no 

 evidences of the presence of the substance. 



5. I have examined three sjjecimens of alkali formed by the 

 combustion of vegetables that grow on the sea shore, one from 

 juicily, one from Spain, and the third from tlie Roman states, 

 but not one of them afforded a!iy indications of the presence of 

 iodine. 



6. I evaporated a considerable quantity of sea water procured 

 at Sestri of Levanto in Ligiyia, in a part of the bay remote from 

 any source of fresh water ; but I could gain no nneo,uivocal evi- 

 dences of the presence of the compounds of iodine in it. The 

 residual liquor after the common salt had been separated, did 

 not act upon silver nor colour sulplmric acid. The first crjstal* 

 of salt which fell down when fused upon silver, a])])eared to me 

 to tarnish it more than the last ; from which it appeared j)ro- 

 bable that they may have contained some trijile compound 

 of ^ iodine, yet after being ignited, they did not colour sulphuric 

 acid. When a large quantity of this water was electrized by 

 a Voltaic apparatus, and the products separated at the }K>si- 

 tiye pole collected iu a small cup of gold, which was covercsl 

 with cement, except in tiie interior and lower part forming the 

 circuit, a yellow solution was obtained, which when it was ex- 

 posed to the negative pole of a Voltaic apparatus, yielded a 

 black powder fixed in the fire, and not unlike the com])ound 

 formed by heating gold and iodine together; but the quaiUity 

 was too minute to admit of analysis, and a dark-coloured sub- 

 stance is likewise obtained by negatively electrifying oxvmuriate 

 of gold, and there can be no doubt but that' tliis s'uh.stanca 

 formed a principal part of the solution*. 



* loriiiie, like clilnritie, I find comliines l.oth w'th coVI and platinum, 

 when heuUd witb theni, or when thtv are txuo3t(i to ilistn iu its nusceiit 

 state. 



If 



