or SEA- WATER IN THE DIFFERENT PARTS OF THE OCEAN. 
207 
In this kind of decomposition, where sulphuretted hydrogen is formed, the organic 
matter is changed into carbonic acid and water, while the oxygen which this change 
requires is taken from the sulphates, and the sulphuret thus formed takes its oxygen 
again from the hypermanganate. Thus the result of the series of decompositions is the 
revival of the same sulphate with which it began, and the formation of carbonic acid 
and water from the organic matter which was present. In the second case, where the 
hypermanganate directly oxidizes the organic matter, the same quantity of oxygen must 
be used, and the same products are obtained. In both cases the oxygen is ultimately 
derived from the hypermanganate. This reasoning supposes that no oxygen from the 
atmosphere is absorbed, and no sulphuretted hydrogen has escaped during the opera- 
tions. The absorption of oxygen is prevented by the cork of the bottle, but when it is 
opened some sulphuretted hydrogen certainly will escape, and we may conclude that in 
the cases where sulphuretted hydrogen is formed, there has been a little more organic 
matter than the hypermanganate indicates. 
This fermentation of the sea-water occasions of course a loss of sulphuric acid, and 
makes the analysis in some degree inaccurate. The greatest loss of sulphuric acid which 
I have observed was in the case of the water from the 4 Satellite ’ above mentioned, 
where the proportion to chlorine was found to be 9T3: 100, while the mean proportion 
is 1T94: 100, thus about one-seventh of the sulphuric acid was decomposed. It is very 
probable that this great quantity of organic matter is owing to the water of the Eio de 
la Plata, because the water contained only 17*721 chlorine, while the mean number for 
that region is 19*376, which seems to prove a considerable admixture of river-water. I 
may here also mention a curious instance where no decomposition had taken place, 
although the circumstances seemed to be very favourable for it. The sample had been 
taken by the late Sir James Koss in 1841, at 77° 32' S. lat., in the neighbourhood of the 
great ice-barrier, and it was marked “ Sea-water containing animalculae.” It was very 
muddy when I opened the bottle, but had not the least smell of sulphuretted hydro- 
gen. Tested without being filtered, 1000 grains bleached 180 drops of the hyperman- 
ganate ; when filtered the same quantity bleached 39 drops. It contained thus a great 
quantity of organic matter. The quantity of chlorine was 15*748, which proves that 
it was much diluted, probably by the melted ice from the barrier ; the proportion of 
sulphuric acid to chlorine was 11*65 : 100, which approaches pretty near to the normal 
proportion. It had been about twenty years in the bottle when I analyzed it, and the 
cork was sound. It is difficult to conceive why this water had not suffered any decom- 
position. 
8. Phosphorus . — This element, in combination with oxygen, is a never failing part of 
sea-water, which remains as phosphate of lime when the water is evaporated to dryness 
and the salts remaining dissolved in boiling water. The small quantity of insoluble 
matter which remains consists of phosphate of lime, sulphates of baryta and of strontia, 
fluoride of calcium, carbonate of lime, and silica. When this mixed substance is heated 
with muriatic acid, filtered, and tested with molybdate of ammonia, phosphoric acid will 
