C 251 j 



therefore be used as a manure as soon as the vegeta- 

 ble fibre is removed from it. 



Sea weeds , consisting of different species of fuci, 

 algae, and confervas, are much used as a manure on 

 the sea coasts of Britain and Ireland. By digesting 

 the common fucus, which is the sea weed usually most 

 abundant on the coast, in boiling water, I obtained 

 from it one-eighth of a gelatinous substance which 

 had characters similar to mucilage. A quantity dis- 

 tilled gave nearly four-fifths of its weight of water, 

 but no ammonia ; the water had an empyreumatic and 

 slightly sour taste ; the ashes contained sea salt, car- 

 bonate of soda, and carbonaceous matter. The gase- 

 ous matter afforded was small in quantity, principally 

 carbonic acid and gaseous oxide of carbon, with a lit- 

 tle hydro-carbonate. This manure is transient in its 

 effects, and does not last for more than a single crop, 

 which is easily accounted for from the large quantity 

 of water, or the elements of water, it contains. It de- 

 cays without producing heat when exposed to the at- 

 mosphere, and seems as it were to melt down and dis- 

 solve away. I have seen a large heap entirely des- 

 troyed in less than two years, nothing remaining but 

 a little black fibrous matter. 



I suffered some of the firmest part of a fucus to 

 remain in a close jar containing atmospheric air for a 

 fortnight : in this time it had become very much 

 shrivelled ; the sides of the jar were lined with dew. 

 The air examined was found to have lost oxygene, 

 and contained carbonic acid gas. 



Sea weed is sometimes suffered to ferment be- 

 fore it is used $ but this process seems wholly unne- 



