128 DIFFERENTIATION AND SPECIFICITY OF STARCHES. 



Zulkowsky's previous work was confirmed and extended. It was found, by heatinf^ 

 ytarch-i)aste to 190°, that soluble starch was formed having a specific rotation of 188.3; 

 at 200° crythrodextrin appeared. It gives a cherry-red reaction with iodine, and had a 

 specific rotation of 181. At 210° another dextrin is formed, which is recorded as giving a 

 brownish-yellow reaction with iodine and having a specific rotatory power of 173.5°. Both 

 dextrins were found to reduce Fehling's solution. When the preparation was heated at 

 210° for a long time two other products were formed, one of which resembled gum arable. 

 Ost (Chem. Zeit., 1895, xix, 1501) prepared the dextrinous pi'oduct according to Zul- 

 kowsld's process and found a glucose value of 90 per cent. He concluded that this substance 

 is not a true dextrin. 



Bacillus amylohacler was used by Villiers (Compt. rend., 1891, cxii, 435, 536) to con- 

 vert starch into dextrins. Potato starch was made into a paste with tap-water; the paste 

 put in a flask which it nearly filled; the starch inoculated at 100°; the flask closed with 

 sterilized cotton, and placed in an oven at 40°. Usually liquefaction had occurred by the 

 end of 24 hours. After 2 to 4 days or more a red reaction with iodine was obtained. The 

 preparation had the odor of butyric acid, of which it contained about 0.3 part for each 

 100 of starch. The chief product was dextrins. He states that it remains to be shown 

 whether or not these dextrins are identical with those formed by the action of diastase or 

 acid, and that it is remarkable that they are formed without an accompanying formation 

 of either maltose or glucose. Villiers prepared the dextrins by filtration, drying, resolution, 

 and precipitation with alcohol. They occur in the form of a white, friable, hygroscopic 

 mass, which consists of several dextrins having different rotatory and reducing powers, 

 and different reactions with iodine. The dextrin having the highest rotatory power has 

 the lowest reducing power and gives a red reaction with iodine, while those having lower 

 rotatory powers and higher reducing powers do not give a color reaction with iodine. In 

 Villiers's second article he states that besides the dextrins there is formed about 0.3 per 

 cent of a carbohydrate that is dissolved in the alcohol used to precipitate the dextrins; 

 that this is somewhat soluble in hot water and that it may be deposited in the form of 

 fine crystals having the composition of C12H20O10+3H2O. It is dextro-rotatory, {a)x,= 

 -}-159.4°; it is unfermentable ; it does not reduce Fehling's solution; and it does not form an 

 osazone. Another product had the properties of cellulose, and was converted into glucose 

 by warm, dilute mineral acids. 



Dextrin-like products were obtained by Berge (Jour. Soc. Chem. Industry, 1892, 

 XI, 448) by subjecting starch and various amylaceous substances in a dry state to the 

 action of sulphurous anliydride. The substances are placed in a closed vessel into which 

 sulphurous anhj'dride is introduced until all of the air is expelled, and the vessel then 

 heated on an oil bath to a temperature of 120° to 190°, depending upon the nature of the 

 product desired. Upon the completion of the conversion the gas is permitted to escape. 



As far back as 1846 Magendie showed that the blood has the power of converting 

 starch into sugar, and more or less attention was given to this property by Claude Bernard, 

 Hensen, Schiff, von Wittich, and other investigators. In 1892 Bial, under the guidance of 

 Rohmann, and also Rohmann himself, studied the diastatic actions of the sera of the blood 

 and lymph. Bial (Archiv f. ges. Physiologic, 1892, lii, 137; 1893, 156) found that these 

 sera reduce starch to dextrin, maltose, and glucose. Rohmann (Archiv f. ges. Physiologic, 

 1892, LII, 157; Ber. d. d. chem. Gesellsch., 1892, xxv, 3652) subjected 100 grams of potato 

 starch converted by heat into a paste with 5 liters of water, after cooling, to the action of 1 

 liter of bullock's serum, to which was added 100 c.c. of a 10 per cent alcohohc solution of 

 thymol to prevent bacterial action. This preparation was kept at 32° for 24 hours, at the 

 end of which time there were present dextrin, giving a brown reaction with iodine, acliroo- 

 dextrin, glucose, and possibly maltose. After 10 hours' action a mixture of dextrin was 

 present (which Rohmann calls porphyrodextrin), which gave a brown reaction with iodine, 



