30 
Proceedings of Royal Society of Edinlicrgli. [sess. 
Abstract of Paper on the “ Digestion of Sugars.” 
By W. G. Aitchisou Robertson, M.D., D.Sc., F.B.C.P.E. 
(Read February 20, 1893.) 
Most individuals consume daily nearly a pound of carbohydrate 
food in the form of starch or sugar. 
The cheapness of sugar in recent times has led to its increased 
consumption. In 1891 the annual consumpt of cane sugar alone per 
head of the population was estimated at 80 lbs. 
There can be no doubt that the increased consumption of sugar 
has been followed by an increase in the number of cases of acid 
dyspepsia, which may in some individuals become so troublesome 
that they are obliged to abandon saccharine articles of diet as 
much as possible. 
I have been led by the interest and importance of this subject to 
study some of the changes that cane sugar undergoes during 
digestion. 
When a solution of cane sugar is heated for some time in presence 
of a dilute mineral acid, it becomes inverted, — that is to say, it links 
on a molecule of water, and then splits into equal parts of dextrose 
and Isevulose. 
Richet affirms, while Hoppe-Seyler denies, that the saliva inverts 
cane sugar. I have therefore sought to determine this point. I 
first ascertained the effect of heat alone on a solution of cane sugar. 
I kept a 20 p.c. solution of ,cane sugar in distilled water at a tem- 
perature of 38° C. for one hour, and found that invert sugar amount- 
ing to 0T9 p.c. was produced ; and that at the end of two hours it 
increased to 0‘252 p.c. 
I then made a 20 p.c. solution of cane sugar in human saliva, and 
kept it at the same temperature as in the previous case. At the end 
of one hour the invert sugar amounted to 0‘2 p.c., as against 0T9 
p.c. in the previous case ; while at the end of two hours 0*27 p.c., as 
against 0‘252 p.c. in the preceding experiment. 
The amount of invert sugar produced in^the two cases v/as so 
