Studier öfver svensk tång, företrädesvis från Öresund 
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equally large, the former predominating somewhat over the latter. Potassium always 
occurs in abundance where the quantity of chlorine is large. Especially Chorda 
stands out with an average of 7 per cent, of potash, and in one instance as much 
as 12 per cent., the chlorine at the same time exceeding above 6 per cent. The 
quantity of lime is highly varying, which may be due to adhering calciferous or- 
ganisms. Magnesium is more constant and is low in all seaweeds, except in Ulva. 
The quantity of sulphuric acid in the asb of all seaweeds is large, except in Zoster a ; 
in Ulva and in the old parts of the brown algae it may reach to 6 per cent, and 
above that. Very likely, however, the sulphur to an essential degree is originally 
to be found in an organic form, as it is only partly washed out by treatment with 
water. The quantity of chlorine is very much varying, which to a certain degree 
is due to its being washed out in less salty water. The quantity is larger in sea- 
weeds living in deep water than in those growing in the littoral regions. The 
quantity of iodine varies more than any other substance. While Zostera, Ulva and 
other green seaweeds scarcely contain any trace of it and the quantity of iodine in 
the brown algae of the Sound only is some hundredth part of per cent., Laminaria 
is characterized by a great capacity of taking in this matter, quantities of 0.5 per 
cent, being observed. 
The writer has further shown the changes which are occasioned by the 
washing out of the seaweeds, by rainfall, and by preservation in piles. These 
changes are of importance for the utilization of the seaweed for practical purposes. 
By rainfall the inorganic matter in the first place is ■washed out, especially chlorine 
and potassium, and also sodium, magnesium, and sulphuric acid, but extremely little 
of phosphoric acid, lime, and iron. The organic matter, too, is exposed to such 
washing out, which is also the case with nitrogen that diminishes proportionally to 
the organic substance. The consequence of this is that a mass of seaweed is ob- 
tained poor in potassium and chlorine, but rich in phosphoric acid, lime, and iron. 
Putrefaction has no considerable influence on these conditions, especially not in the case 
of the here very common eelgrass; in Ulva the changes seem to be more radical. 
Finally the writer has made some suggestions on the use of seaweed as fodder 
and manure. As fodder Ulva stands foremost, containing, as it does, a large quan- 
tity of soluble albumen and very little cellulose. Next comes Zostera. The brown 
algae, of frequent occurrence in the Sound, have no great value owing to their 
want of soluble albumen. Ascophyllum, very common on the Western coast, has 
been used of old for pig’s food, which is due to its large quantity of fat and the 
occurrence of soluble albumen. All seaweeds, before being used for food, should be 
freed from salts through washing out. 
As manure, too, Ulva stands first. In this respect the nitrogen and the potash 
are of the greatest importance in all seaweeds. The quantity of phosphoric acid, 
on the contrary, is uncommonly small in all of them, and for this reason an ad- 
mixture of manure containing phosphoric acid generally is necessaiy. When sea- 
weed is exposed to the air and is heaped up in piles, potash especially is washed 
