and Observations on Iodine* 
505 
2. M. Berard was so good as to order a considerable 
quantity of the species of ulva, which abounds on the coast of 
Languedoc, to be burnt for me at his laboratory at Montpellier. 
The ashes consisted for the most part of common salt, but a 
small quantity of alkaline lixivium which was obtained from 
them, afforded a red fluid when acted upon by sulphuric acid, 
and a similar colour I found was produced, when a solution of 
subcarbonate of soda and common salt, containing a minute 
quantity of the compound of sodium and iodine, was treated in 
the same manner by the acid. 
3. One of the best tests of the presence of a very minute 
quantity of iodine in compounds, is their action upon silver. 
Water when it contains less than P^rt of its weight of the 
double or triple alkaline compounds of iodine tarnishes polished 
silver. 
The effect produced by compounds of iodine, may be dis- 
tinguished from that produced by sulphurets or sulphuretted 
hydrogene by this circumstance, that solutions containing 
sulphurets or sulphuretted hydrogene, by being boiled with a 
little muriatic acid, no longer tarnish the metal, whereas solu- 
tions containing iodine still retain the power. 
4. Amongst a number of sea weeds that were obligingly 
given me for examination, by professor Viviani of Genoa, the 
ashes of the following afforded slight indications of the pre- 
sence of iodine, 
Fucus cartilagineus. Fiicus filamentosus. 
— - membranaceus. Ulva pavonia. 
rubens. linza. 
In the ashes of the corallines and sponges, I could discover no 
evidences of the presence of the substance. 
