B.—CHEMISTRY 39 
quantities present of these so-called extraneous materials seem to have no 
easily recognisable stoicheiometric relation to the unit chemical molecule. 
CH,OH 
cH,04 
cH,0H HOH CH,0H Y ,,0H 
Methylated starches of different origins have now been examined by the 
method of gravimetric assay of the end group, particularly the starches 
from potato and maize, and also a less common variety known as waxy 
maize starch. Investigated by these methods and prepared in a variety 
of ways, all three methylated starches from these sources show a remarkable 
uniformity in the chain-length of the chemical unit. This corresponds 
to a molecular weight for starch of about 5,000, or 25 glucose residues. 
CHOMe 
H fe} H 
H 
OMe 
° 
rs] ome 
1 
Tetramethyl Trimethyl glucose. 
glucose. 
Methylated amylose and amylopectin (* = 25). 
Methylated glycogen (¥ = 12 — 18). 
Despite this fact the many different samples we have prepared of methy- 
lated starches exhibit viscosities which, by the use of the Staudinger 
constant, would seem to indicate a chain length of 5, 10, or 20 times that 
just given. The same may also be said of the starch acetates. The 
amylopectin or «-amylose portion, representing the less soluble part of 
