12 Analysis of Sea Water. | 
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Arr. I].—Analysis. of Sea Water as it evists in the English 
_ Channel near Brighton ; by G. Scuweirzer, M. D.* 
Bios unaware of the existence of a correct analysis of sea- 
Pr as it exists in the British Channel, particularly with refer- 
ence to the quantity of iodine and becumann it contains, I have — 
~ undertaken at the request of several friends to analyze it. It is— ‘a 
- not my intention to enter into the minutize of the process em- 
‘ployed, particularly as I have on a former occasion, in a small — 
mphlet entitled “ An Analysis of the Congress Spring of Sara- 
toga in America,” published in March, 1838, given a detailed 4 
account of the mode I adopt in analyzing mineral waters. ‘The 
chief object I have in view in the present communication is, to ~ 
explain the method I have employed in ascertaining the propor-. — 
tion of iodine and bromine contained in a given quantity of sea- 
water. But before I enter upon the subject, it may not be out of | 
place to show how far tests act upon iodine when in connexion — 
with an alkali, and ina solution also containing bromides and © 
_ From experiment I have ascertained that a minute quantity of 
iodine in distilled water, equal to no more than 1,500,000th part — 
of the whole, will be distinctly indicated when mixed wie ¢ 
starch, dilute sulphuric acid, and chlorine. 
or the production of such delicate reaction, I add to every : 
‘500 grains of fluid one drop of diluted sulphuric acid, a small — 
quantity of paste of potato starch, and two drops of a weak so- 
lution of chlorine, consisting of one part of a saturated solution 
diluted with 20 to 25 times its volume of distilled water. The . 
solution gives no indication of the presence of iodine in the fluid ~ 
until a sufficient time has been allowed for the separation of the — 
starch, when a decided pink hue will be visible on the surface at 
the precipitate if iodine be present. It has been supposed that 
the substitution of pink for blue in the iodide of starch produced; 
arises from the presence of bromine; but this I have ascertained 
is not correct, as it depends ontixely: on the minute quantity of 
the precipitate acted upon by free chlorine or bromine. The 
lowing experiment will prove this fact. In order to aacertaly: WY the 
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aed the Lond. and ~~ Phil. _ for July, 1839; Semana: by , the : 
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