SCIENCE. 



465 



positive that dextrin does not reduce the copper solution 

 except on prolonged boiling. 



My own experience is that dextrine does not reduce 

 Fehling's solution except on prolonged boiling and then 

 by the dextrine being slowly converted into dextrose. 



To secure the reduction of the dextrose and the re- 

 ducible portion of maltose it is not necessary to boil the 

 solution more than two minutes, and during this time the 

 amount of dextrine reduced is wholly inappreciable. 



Color with Iodine. Bondonneau ( 9 ) says, dextrine 

 colors a solution of iodine a dark red, but that it is 

 without effect on caustic soda. Musculus & Gruber ( 9 ), 

 found that some varieties of dextrine colored iodine 

 solution red, while others were without action on it. 



In general it will be found that most substances pur- 

 porting to be dextrine give a reddish color with iodine. 

 For my part I do not know of any method by which 

 absolutely pure dextrine can be prepared. 



Fermentability. Respecting this property the most 

 contradictory statements are found. The weight of 

 authority leans to the non-fermentible doctrine. It is 

 probable that before dextrine ferments it is first converted 

 into dextrose. 



Formation. In addition to the method by roasting, 

 dextrine is always formed when diastase or dilute acids 

 act on starch. 



Some authorities maintain that dextrine in such cases 

 is always the first transformation product and that the 

 others are derived from it. 



According to Musculus ( 10 ), dextrose and dextrin are 

 formed synchronously by the action of sulphuric acid 

 on starch and in the proportions of one part of the 

 former to two of the latter. This proportion is main- 

 tained until all the starch disappears. The further ac- 

 tion of the acid then tends to convert the dextrin into 

 dextrose. O'Sullivan ( u ) states that by the action of 

 diastase, both dextrine and maltose, and nothing else, 

 are first produced from starch under certain conditions 

 of temperature (below 63 ), and in the proportions of 

 one part of the former to two of the latter. The pro- 

 portion, however, only obtains when the specific rotatory 

 power of the mixed bodies is equal to 171 °. 



From a careful study of all the data I could obtain 

 I concluded that very little is yet known of the real 

 proportions of dextrine which amyloses formed by 

 heating starch with dilute acids contain. 



Maltose. Dubranfaut ( I2 ) first pointed out the prob- 

 able existence of a third transformation product of 

 starc.i in addition to the two which had long been 

 known. But we must, accord to O'Sullivan ( 13 ) the merit 

 of having first isolated and studied the properties of this 

 body. He has given in the Journal of the Chemical 

 Society, within the last decade several papers on the prop- 

 erties of this important saccharide. He gives its specific 

 rotatory power (a)= 150 . The same value is also given 

 by Musculus and Gruber, ( 14 ), 



Joshida 15 found a slightly higher number. For (a)j this 

 would give 135. °36. 



Maltose is formed chiefly by the action of diastase on 

 starch at a temperature not exceeding 75 . But it is also 

 formed, but in smaller quantities by the action of dilute 

 acids. 



It is well established that maltose has the power of re- 

 ducing the alkaline copper solution and in the proportion 

 of 65 to 100 compared with dextrose. We here find an 

 easy explanation of the fact that so many chemists have af- 

 firmed that dextrine acted on copper solutions. In all these 

 cases the dextrine doubtless contained maltose. With- 

 out citing further from the literature of maltose, which is 



(°) Loc. cit. 



( 10 ( Annal. de Chem. et Phys., p. 203. 



( n ) Chemical News. 1876, 861-218. 



(12). Anall. de Chem. et Phys. (3) XXI, p. 168, 



13) . Jour. Chem. Soc. Vol. X, 2d series. 



14) . Loc. cit. 



(15). Chem. News, 1881, 



all recent, I wish to call your attention again to the 

 numbers representing its rotating and reducing power, 

 viz. 1 50 and 65. 



3d. Dextrose. This substance is the final product of 

 a complete saccharification of starch. It has a slightly 

 bitter taste, which is probably due to the development of 

 a bitter principle on long boiling with acids. This bitter 

 taste is not noticed in the products less perfectly con- 

 verted. 



Dextrose possesses in the highest degree the power of 

 reducing the copper solutions. One gramme reduces 

 2.205 g- weighed as cupric oxide. Its specific rotatory 

 power has been the subject of much controversy. 



O'Sullivan gives 57°. 6 = (a) 



Tollens " 56 = " 



" 53-17 = (a) j. ( ,6 ). 



The differences in results which the above numbers 

 show do not indicate so much errors of observation as 

 they do the impurities which the purest dextrose is likely 

 to contain. As a mean of these numbers, we may take 

 (a) = 56 and (a) j. = 50.5 (by calculation). 



Pure dextrose is almost insoluble in absolute alcohol, 

 while it is very soluble in water. According to Anthon 

 ( n ) 100 parts water dissolve 81.68 parts dextrose. To 

 dissolve one part, 50 parts of alcohol, .83 sp. gr. are re- 

 quired. When subjected to fermentation, dextrose affords 

 48 per cent alcohol ( 18 ), while cane sugar and maltose 

 each gives 51 per cent and dextrine none at all. 



I have thought it useful to give the above brief reswne 

 of the literature of amylose, because the conclusions to be 

 drawn from it will go far to explain the anomalies of the 

 numbers which the following analyses and methods of 

 analysis will show. The whole subject is a matter of 

 considerable scientific interest on account of the immense 

 production of amylose in this country and the laws which 

 some of the States have passed to regulate its sale. In 

 the present state of our knowledge I am at a loss to see 

 how the real constitution of an amylose, or mixed sugar, 

 can be established before a court of justice. To show 

 this I will give synopses of a few of the 



METHODS OF ANALYSIS 



which have been proposed. 



I shall not attempt to give an out-line of all the 

 methods which have been proposed for determining the 

 amount of dextrine and dextrose in amylose. Until with- 

 in a few years they were all based upon the assumption 

 that these were the only transformation products of 

 starch — an assumption which we know to be false. Re- 

 duced to first principles, all the methods may be com- 

 prised under three heads. 



1st. The reduction of certain metallic salts by the 

 dextrose, and estimation of dextrine by difference. 



2d. Fermentation of dextrose and estimation of dex- 

 trine by difference. 



yd. Precipitation of the dextrine by strong alcohol and 

 estimation of the dextrose by difference. 



Remembering the facts established in the first part of 

 this paper, it will not be hard to show the fallacies of these 

 several methods. 



1st. Metallic salts, especially the compounds of cop- 

 per, mercury and ferro-cyonigen, are all reduced by 

 maltose as well as by dextrose, and on prolonged boiling 

 in a slight degree by dextrine also. Thus the total reduc- 

 ing effect does not measure the amount of dextrose pres- 

 ent only in case maltose is completely absent. In com- 

 mercial amyloses this is never the case unless it be in 

 rare instances of high pressure conversion. 



2d. Fermentation not only converts dextrose into 

 alcohol and carbonic dioxide, but acts in the same man- 

 ner on maltose. For a given weight maltose gives even 



(16) . Ber. d. Deutsh Chem. Gesel., 1876, p. 420. 



(17) . (Ding. Jouruai, CLV, p. 41). 



(18) . O'Sullivan loc, cit. 



