348 RELATIONS BETWEEN SUGAR AND TARTARIC ACID. 
ART. LXXXVI.— ON THE RELATIONS EXISTING BETWEEN 
SUGAR AND TARTARIC ACID. 
By M. Bouchard at. 
Sugar and tartaric acid possess characters in common 
which are well worthy the attention of Chemists. M. 
Bouchardat thus describes them : 
When sugar or tartaric acid is thrown on to incandescent 
coals, in either case empyreumatic products are given off, 
which are distinguished by the odor of caramel. 
When pounded in a mortar, in the dark, both crystallized 
sugar and tartaric acid emit a manifest electric light. The 
other organic acid, and citric acid in particular, do not pos- 
sess this property. It therefore follows that we may dis- 
tinguish tartaric from citric acid, and ascertain whether the 
latter has been adulterated with the former. 
Sugars in solution act upon polarised light, possessing in 
a high degree the power of rotating the plane of vibration. 
Cane-sugar, which has been changed by acids under the 
influence of heat, possesses this power, and^the direction of 
the rotation may even be altered by the action of the acid. 
Tartaric acid, either free or combined with water, with 
bases, or with boracic acid, presents remarkable instances 
of variations of rotatory power. 
A concentrated solution of citric acid being void of rota- 
tory power, nevertheless acquires that property if mixed 
with tartaric acid. It therefore follows that we may also, 
by this means, detect the adulteration of citric with tartaric 
acid. 
In addition to the characters possessed in common jy 
sugar and tartaric acid, very frequently the decomposition 
of these two substances gives rise to similar products. — 
Pharm. Jour., from Journal de Pharmacie. 
