50 Journal of Agricultural Research voi. iv, no. i 



Stanford (30) prepared a considerable number of compounds similar 

 to those described here, although his data presented some discrepancies. 

 An inspection of the table will indicate certain theoretical possibilities 

 for the use of alginates as sizes or mordants, but the practical difl&culties 

 of preparation would probably prevent any commercial application of 

 such products in competition with the various low-priced materials now 

 used for these purposes. 



CARBOHYDRATES PRECIPITABLE BY ALCOHOL 



The alcohol-precipitable matter was prepared by treating the dried 

 and ground kelp with a weakly acid solution, and adding sufficient 

 strong alcohol to the filtrate to cause a complete precipitation. The 

 flocculent precipitate was filtered by suction and washed with alcohol; 

 the weight of the ash was subtracted from the total dry weight. The 

 product very readily absorbed water from the atmosphere, soon becom- 

 ing mucilaginous. The dried substance contained i .2 per cent of nitrogen 

 and yielded furfural, corresponding to 13.2 per cent of pentosan. No 

 color test was given with iodin and no reduction with Fehling's solution. 

 The moist precipitate was boiled several hours with a 2 per cent solution 

 of sulphuric acid when the solution produced considerable reduction of 

 the alkaline copper solution. Upon drying, the precipitate became very 

 resistant to solution and to hydrolysis. The percentages in the plant 

 of the carbohydrate bodies precipitated by alcohol are much less than 

 for algin. (See Table III.) In the plants of Macrocystis pyrijera the 

 stems show uniformly higher percentages than the leaves. 



CELLULOSE 



A composite sample of fiber, obtained as in the crude fiber method, 

 was treated by the method of Cross and Bevan (5, p. 94-95), by chlori- 

 nation and boiling with alkaline sodium sulphite. Final decolorization 

 was effected with potassium permanganate. Pure cellulose was thus 

 obtained and was found to make up approximately one-half of the crude 

 fiber, or calculated on the whole dry plant, 3 to 4 per cent. 



HYDROLYSIS OF KELP 



Acid hydrolysis of the dried kelp yielded copper-reducing substances 

 only with great difficulty. Ten hours' boiling with a 2 per cent sul- 

 phuric-acid solution gave the following amounts of reduced copper 

 calculated as dextrose: 



Per cent. 



Macrocystis pyrifera, leaves 6. 4 



Macrocystis pyrifera, stems 7. o 



Pelagophycus porra, leaves 9. o 



Pelagophycus porra, stems 8. 6 



Nereocystis luetkeana, leaves 5. 6 



Per cent. 



Nereocystis luetkeana, stems 5. 7 



Egregia menziesii 9.0 



Lamiiiaria andersonii i5- 7 



Iridaea spp 19. 8 



