BASIC INVESTIGATIONS. 93 



Schiitzenberger (Compt. rend., 1866, 61, 485) recorded that anhydrous acetic acid 

 produces from starch two compounds, one soluble and the other insoluble, both of which 

 yield dextrin. Philip (Zeit. f. Chemie, 1867, x, 400) noted that by boiling starch in dilute 

 acid there was not produced a constant proportion of sugai", as Musculus supposed, but 

 variable proportions according to the quantity of acid used. Low (Zeit. f. Chemie, 

 1867, X, 510) broke starch-paste down into formic acid, carbonic acid, and carbon by 

 keeping it at a temperature of 170°. 



Jessen (Jour. f. prakt. Chemie, 1868, cv, 65) resolved starch into three essential 

 components: (1) Envelopes or cell-coats which are insoluble in hot or cold water (the 

 amidine tegumentaire of Guerin) ; (2) starch which is soluble in cold water (the amylogen 

 of Delffs, the amidine of Guerin- Varry) ; (3) starch which is soluble in hot water (55° to 

 80°), and which may be called amylin (the amidin soluble of Guerin- Varry and the amylin 

 of Maschke, Delffs, Melsens, and Schulze). 



Musculus (Compt. rend., 1869, lxviii, 1267; 1870, lxx, 857) ascertained that in the 

 breaking down of starch by diastase or acid into colorless or true dextrin (achroodextrin) 

 there is formed a modification which he terms an insoluble dextrin. This dextrin was found 

 to be insoluble in cold water, but soluble in water at 50° to 60°. An aqueous solution 

 yielded a wine color with iodine, and when in an air-dried condition it became colored 

 a ^•iolet, yellow, or brown with iodine, and it was found to yield less sugar than starch. 



Schwarzer (Jour. f. prakt. Chemie, 1870, cix, 212), in common with Payen, Philip, and 

 others, looked upon Musculus's theory of the splitting of the starch molecule directly into 

 dextrin and sugar as being incorrect, even though the formation of dextrin and sugar occurs 

 in definite ratio. Schwarzer studied the actions of diastase with reference to the quantities 

 and characters of the products under various conditions. He observed that after the 

 reaction to iodine ceased, the formation of sugar was about completed, so that a contin- 

 uance of the action resulted in the formation of only very small quantities of sugar; 

 that at all temperatures from 60° down to 0°, using varying amounts of diastase, there 

 is formed from 50 to 53 per cent of sugar; that at temperatures above 60° less sugar is 

 formed than at lower temperatures; that if malt extract acts for some time at 70°, it 

 becomes so changed that it forms very little sugar if the temperature be lowered; that 

 if a starch-solution prepared at 70°, v/hich contains 27 per cent of sugar, is lowered in 

 temperature, and diastase is added, the sugar-content can be increased to 52 per cent; 

 that the appearances of the starch preparation when transformed at different temper- 

 atures are very varied — at 70° the undissolved starch capsules are grouped into brown 

 flakes, while at lower temperatures white flakes appear which form a thin layer at the 

 bottom of a clear liquid; and that a definite amount of diastase is capable of transforming 

 only a limited amount of starch, since there is a gradual transformation of the diastase 

 into an inactive form. 



Schulze and Marker (Jour. f. Land\virtsch., 1872, xx, 56) confirmed the records of 

 several previous investigators that through the action of diastase starch is almost com- 

 pletely converted into definite proportions of dextrin and sugar. 



THE BASIC INVESTIGATIONS OF GRIESSMAYER, BRUCKE, OSULLIVAN, AND 



MUSCULUS AND GRUBER. 



The present day conceptions of the primary decomposition products of starch that 

 are formed through the actions of enzymes, weak acids, etc., may be credited essentially 

 to KirchhofT ("1811), Biot and Persoz (1833), Payen and Persoz (1834), Musculus (1860- 

 1870), Griessmayer (1871), Briicke (1872), and O'Sullivan (1872). Kirchhoff was the 

 first to announce the formation of sugar; Biot and Persoz prepared and studied the prop- 

 erties of dextrin and gave this substance its name; Payen and Persoz believed that dextrin 

 is the inner substance of the starch-grain and that sugar is formed from it; and Musculus 



