336 PROCEEDINGS OF SECTION B. 
No. 11.—ON THE ESTIMATION OF WHEATMEAL IN 
OATMEAL BY A GRAVIMETRIC PROCESS. 
By W. M. Donerty, F.C.S. 
(Read Monday, January 10, 1898. ) 
OATMEAL is frequently found largely adulterated with wheatmeal. 
The well-marked and characteristic differences existing between 
the starch granules of the oat and the wheat render the discovery 
of this fact a matter of more or less simplicity. At the present 
time, the method used for estimating this adulteration is wholly 
microscopical. But it may have occurred to some of those who 
have to deal with this question that the counting of starch 
granules as a means of arriving at percentages of mixed “meals” 
is not altogether satisfactory, or devoid of objection; for, in 
the first place, it is a very difficult matter to obtain a slide that 
will fairly represent a large sample. The quantity of the sample 
under observation in the microscopic field of vision is always so 
minute that the preparation of a large number of slides becomes 
necessary in order to obtain even an approximate degree of 
accuracy. This, at least has been my experience, notwithstanding 
a most careful mixing of the samples undergoing analyses. In 
the second place, a correct estimation of the proportion of different 
starch granules does not imply the same correctness with regard 
to the meals in which the granules are found. This will be evident 
from the fact that the percentage of starch in wheat is greater 
than the percentage of starch in the oat, the ratio being often as 
65 to 50. 
The means which I now propose for the substitution of the 
quantitative microscopical method, has the advantage of bringing 
the balance into requisition, and depends upon the difference in 
the quantities of fat naturally present in the oat and in the wheat. 
It will be obvious that before any data of value can be obtained 
from a given sample, it will be essential to discover if there is 
constancy in the fat-yields of both the wheat and the oat. In the 
numerous works treating or touching on the composition of these 
cereals, the fat content of neither the one or the other is quite 
constantly stated, but varies within certain narrow limits.* 
Acknowledging this variation, I do not think, though it be found 
to exist universally, that it will at all affect the general application 
or utility of this process. However this may be, my own deter- 
minations of the fat in genuine oatmeal and in wheatmeal procured 
in Sydney, and extending over several months, show in the case of 
* European and American observers place the fat yield generally between 6 and 7 per 
cent. 
