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



characteristics correspond to those described by Stanford, although 

 KyUn made his original extraction with water rather than alkali. 



In this laboratory experiments were inaugurated to determine to what 

 extent a similar substance might be present in the Pacific coast kelps, 

 and in addition its general chemical characteristics. It was found that 

 the maximum yield of algin was obtainable by digestion in the cold and 

 with a dilute sodium-carbonate solution (2 per cent). The use of 

 stronger alkalies or the application of heat is unfavorable, probably 

 because of a tendency of the body to decompose under such conditions. 

 The following procedure was adopted for the estimation of the algin 

 fraction : 



Two gm. of kelp were digested in the cold for 24 hours with a 2 per 

 cent sodium-carbonate solution. The residue was filtered off and washed 

 with cold water. Twenty c. c. of dilute hydrochloric acid were added 

 to the filtrate, and the precipitate was allowed to stand for 24 hours. 

 It was then filtered on a linen cloth, washed, dried, weighed, ignited, and 

 the weight of the ash subtracted. 



The percentages obtained by this method varied from 13 to 24, cal- 

 culated on the dry kelp. (See Table III.) Iridaea spp. again form an 

 exception, having only i per cent of this complex. The general proper- 

 ties of the algin thus obtained are as follows: Solubility in sodium car- 

 bonate, ammonia, and other alkalies, with formation of viscous solutions 

 exceedingly difficult of filtration; insolubility in water, in strong acids, 

 in alcohol, also in ether, benzine, turpentine, etc.; resistance to solution 

 after complete drying; precipitation by copper and other heavy metals. 

 Long standing in even a weak alkaline solution causes a decomposition 

 or fermentation to take place, so that precipitation with acid is no longer 

 possible. 



A sample of algin was subjected to further purification by three repre- 

 cipitations with hydrochloric acid and two by alcohol from the slightly 

 alkaline solution. The product was finally bleached with sulphurous 

 acid, and was thoroughly washed and dried. The following analytical 

 results were obtained : 



Per cent. 



Nitrogen o. 3 



Ash 2. 2 



Fiirfural calculated to pentosan 38. 6 



Insoluble after treatment with concentrated nitric acid (cellulose 



derivative) 24. 5 



Some of the moist precipitate was boiled for several hours with a 2 per 

 cent solution of sulphuric acid. The solution gave a good reduction of 

 Fehling's solution. Drying caused the substance to become very much 

 more resistant to hydrolysis. Treatment with nitric acid did not give 

 the mucicracid test for galactan. We may conclude from these observ^a- 

 tions that algin is a very complex resistant compound (or mixture of com- 



