678 



EFFLORESCENCE ON NEW ZEALAND KELPS 



whicli dissolves more of the chloride. On boiling with absolute 

 alcohol, all the mannitol is precipitated. 



Similar compounds of the alkaline chlorides with some of the 

 sugars are already known. 



It is, of course, well known that many of the kelps, or larger 

 FucoideiH, contain abundance of KCl in their ash. Efflorescence 

 of salts on the dry weed is a common phenomenon in hut, dry 

 climates. Whilst most publislied accounts of such efflorescences 

 mention large quantities of KCl, they do not in geneial give 

 anything else except NaCl. On the other hand, so long ago as 

 July 31, 1894, in the Journ. Soc. (hem. Industry, Vol.34, p.608, 

 0. Stanford writes, "Mannite is often seen on the frond of the 

 Laminaria as an efflorescence, and is probably the result of fer- 

 mentation.'" He does not mention the KCl. 



A great deal of attention has been paid in the last few yeais 

 to the constituents of kelps by American woikers, and it is of 

 interest to compare the results in the case of American kelps 

 with those obtained from the New Zealand forms mentioned. 



Mr. Frank K. Cameron, in Report No. 100, United States De- 

 partment of Agriculture, Washington, 1915, writes, p.'Jl, "The 

 salts contained in kelp are mainly potassium and sodium chlorides. 

 To a small extent, calcium and magnesium salts and iodides are 

 present, and probably unimportant amounts of other salts. 

 While the ratio of potassium chloride to sodium chloride varies 

 more or less, for general argument it may be assumed as approx- 

 imately 3 to 2." And on p. 27, "When kelp is dried slowly, 

 there appears on the surface an efflorescence which can more or 

 less readily be shaken off. This efflorescence is a mixture of 

 potassium and sodium chlorides, the former predominating, 

 togetlier with smaller and generally negligible quantities of other 

 salts." It will be noticed that there is no mention of a pre- 

 liminary washing in fresh water, and the question arises— Is the 

 sodium chloride actually derived from the kelp itself, or is it 

 simply due to the evaporation of the adherent sea-water ? No 

 mention is made of the presence of mannitol in the efflorescence. 

 Mr. D. R. Hongland, writing in the Journal of \Agricultural 

 Research, U.S.A., Vol. iv., p.52, April, 1915, says, "The selective 



