Apr. 15, 191S 



Organic Constittients of Kelps 



51 



FORMS OF SULPHUR IN KELP 



Recent researches have emphasized the importance of sulphur as a 

 constituent of plant tissues, and some investigators claim for this ele- 

 ment an important role among the plant foods in which the soil may be 

 deficient. Peterson (19) reviews the literature of the subject and gives 

 tables of analyses showing the total content of sulphur and its forms 

 in various plants considered to be exceptionally high in this constitu- 

 ent. Analyses of the kelp of California indicate much higher percentages 

 of sulphur in many cases than those found in land plants of high sulphur 

 content. It has been noted before that many marine algae in other 

 parts of the world contain considerable quantities of sulphur (6, Bd. 2, p. 

 820) , but the proportion of sulphate to the total sulphur has not received 

 attention. Table VI gives the percentages of total sulphur in various 

 species of California kelps, and also the approximate division of the total 

 sulphur content between organic and inorganic. 



This was effected by leaching out all of the soluble sulphur and directly 

 precipitating the solution with barium chlorid, using essentially the 

 method of Folin. The sulphur precipitated directly by barium chlorid 

 was subtracted from the total sulphur obtained by peroxid fusion and 

 the difference regarded as organic sulphur. This was found to corre- 

 spond approximately to the sulphur driven off on charring the sample. 



TablU VI. — Percentage of sulphur in dried Pacific coast kelp 



No. 



1. 2 



2. I 

 2. 2 



15- I 



15-2 



29. I 



29. 2 



42 



43 



44 



Material used. 



Macrocystis pyrifera, leaves . 

 Macrocystis pyrifera, stems . 

 Macrocystis pyrifera, leaves. 

 Macrocystis pyrifera, stems. 

 Pelagophycus porra, leaves. 

 Pelagophyciis porra, stems. . 

 Nereocystis luetkeana, leaves 

 Nercocystis luetkeana, stems . 



Egregia mennesii 



La^ninaria andersonii 



Iridaea spp 



Organic 

 sulphur. 



44 

 68 

 36 

 54 

 43 

 45 

 31 

 85 

 OS 

 64 



It will be noted that the leaves have a uniformly higher percentage of 

 sulphur than the stems. For Iridaea spp. the amount of sulphur pres- 

 ent is remarkably high. The exact nature of the organic combinations 

 of sulphur is not known. Preliminary experiments indicate that the 

 substances precipitated by alcohol contain a considerable proportion of 

 organic sulphur; the protein sulphur may also be large. In order to 

 test the presence of volatile sulphur compounds, steam distillations of 

 kelp were made, in some cases from 10 per cent hydrochloric-acid 



