372
H . .\. I V E B E R A X I ) \VII.1.1.431
3IC PIIEKSON.
necessary to dissolve ant1 reprecipitate the calcium oxalate. for the first precipitate is sure to coiitain alkaline chlorides i n i.c-i-1. appreciable aiiiouiit. The hisic acetate 1)rccii)itate cannot he used for the tletcriiiiiiatioii ( 1 : aluiiiiiia. since the iiiangaiiescpreci1)itate carries t1on.n .I: little iroii with it, but apparently 110 dcteriiiiiial~leamount of zinc. -.~ .
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ON T H E DETERMINATION O F CANE-SUGAR I N T H E PRESENCE OF COilMERClAL GLUCOSE.’ R S 11
I\,
N’I-lI&K
ANI> \ ~ l I , l , l , A N ~ f L ~ ’ l ~ l ~ . R S O S
I
N the analysis of a great many of the saccharine products found in the markets at the present tinie, the cliemist is confronted with the problem of determining sucrose iii the presence of cointiiercial glucose. T h e official methods for such determinations, either by the use of Fehling’s solution alone or supplemented hy the polariscope, necessitate, as is well knon.ii, the inversion of the sucrose by the action of acids. T h e accuracy of these nietliods requires, as one condition, that the acid uxxl i n inversion exert 110 action upon a n y substance present, other t h a n sucrose, that would in any way affect the reading of the polariscope or would change the power to reduce Fehling’s solution. Since coiiiiiiercial glucose, however. contains a greater or less amount of dextrin, and since this undergoes hydrolysis ivlieii acted upoii b y acids. being cliaiiged thereby into dextrose, tlic question arose as to whether such a change iiiiglit take place during the process of inversion of a n y sucrose present a n d thus vitiate tlic results, T h e specific rotatory power of dextrin 1)eiiig iirarly four times as great as that of dextrose. it is evident that a very slight action would introduce serious errors. T h e inethotl of procedure was. first, to tleteriiiiiie to what extent dextrin is present in conimercial glucose ; second, to ascertain whether any change is produced b y heating with acids as in the cotiiiiioii process of inversion, arid finally to discover some method of eliminating this error, if present. 1 ’This p a p r r a n d t h e one following w e r e sriit tu I l r . EX. W.TT’iley to t i c r e n d lieforc t h e A.soci;ition of Official Ajiricultural Clieniists and t h e n traoirnitted t u t h e editor of t h i s J o U n S A I . f o r pulilicatioli I n c o l l i e ~ ~ l l e l l coft :i niisundc r b t : i ~ l d i nt~l i e y were prlirtc.(l i l l stcad. in tlie I’i-ocee(Iitigs (,[ t h e I,:lcicllth hnliuni Convrrltion of t h ? :iIx~vens%ocin:ion A i t h e requcst of t h e a u t h o r > . asid u i t h t h e coiisrut of tlie Coiiimittee 011 l’aper, a n d P u b licationb. t h e y a r e iiow repriuted III f u i l --I
