THE MANUFACTURE OF KELP. 293 



Many have been struck by the peculiar odour evolved in burning sea- 

 weed ; this at the outset of these experiments arrested my attention, and 

 led me to examine the products evolved in combustion. For this purpose 

 various species of algse were dried, and submitted to a low red heat in a 

 cast-rron retort ; and the products of distillation collected in a series of 

 large "Woulffs bottles ; these products were in all cases the same, differing 

 only in quantity : — 



An inflammable gas ; 



Water, containing carbonate and acetate of ammonia, and a kind of 

 naphtha ; 



A fluid tar, containing a volatile oil, some of which also floated on the 

 water. 



A light charcoal remained in the retort ; tbis was lixiviated with water, 

 and treated as ordinary kelp ; the solutions obtained were colourless, and 

 the salts perfectly white and pure. The mother liquor formed a striking 

 contrast to those usually seen; it was nearly colourless, and contained mere 

 traces of sulphur compounds ; tbe amount of iodine yielded was unusually 

 large. 



The products of distillation were then examined. The gas burnt ex- 

 ceedingly well, giving a flame of little luminosity at first, but becoming 

 very luminous towards the end of the distillation. A portion collected at 

 first gave 41-66 per cent, of carbonic acid. Another portion, collected 

 towards the end of the distillation, gave only 13 - 3 per cent, of carbonic acid, 

 and contained defiant gas. The gas given off in the distillation of wet weed 

 is also inflammable, but the flame is occasionally extinguished by the vapour 

 of water thus simultaneously generated ; a portion of this gas gave 50 - 84 

 per cent, of carbonic acid. 



The condensed liquid was very alkaline ; it yielded ammonia in abund- 

 ance on distillation with lime. The ammonia appears to exist in the liquid 

 as bicarbonate — crystals of this salt were found in some of the gas tubes. 

 The chloride of ammonium in the crude state prepared by neutralising this 

 with hydrochloric acid has an odour of picoline, an alkaloid which is also 

 found in the volatile oil. The naphtha distilled from this liquid burns 

 with a slightly luminous flame. Rectified over lime, its specific gravity i3 

 '826, this commences to boil at '155° ; it is not a simple substance, but 

 appears to be a mixtirre of acetone and methylic spirit ; by repeated rectifi- 

 cation I have succeeded in reducing the boiling point of the first portion 

 below 140° Fah., but I have been unable to effect any definite separation of 

 it, either by treatment with chloride of calcium or by repeated fractional 

 distillation. It has been found impossible to separate methylic spirit from 

 alcohol by this means, although the boiling points of the two liquids differ 

 by about 30° Fahr. I was not surprised, therefore, that I failed to separate 

 the two spirits believed to be the components of this naphtha, the boiling 

 points of which differ only 10°. The presence of acetone considerably im- 

 proves its value, as a solvent of sandarac and shellac. It has also, in the 

 crude state, a peculiar odour, from the presence in small quantity of some 

 ethereal body, of which I have not yet obtained sufficient for examination. 



