ROSELLE. 203 
hot water, and liberated by hydrogen sulphide. After removing 
the lead sulphide, the solution on concentration deposited long 
feathery, deliquescent crystals. These were dissolved in water, 
and an aliquot portion titrated with standard alkali. Another 
portion was treated with uranyl acetate and polarized. The re- 
sults of the titration and the polariscopic readings gave almost 
identical values for dextro malic acid. In this connection it is 
very interesting to note that the factor for computing the dextro 
acid is the same as that found for the ordinary or levo modi- 
fication, since the increased action of the uranyl compound on 
polarized light is of equal value for both acids but in opposite 
directions. Toa third portion of the aqueous solution of the acid, 
an equal volume of alcohol was added and the calcium salt pre- 
cipitated. This was filtered off and dried in a water oven at 
100° to constant weight. A weighed amount was then fused 
with sodium carbonate and potassium nitrate mixture, dissolved 
in water, and the calcium precipitated as oxalate. On titration 
with standard potassium permanganate solution, the following 
results were obtained: 
Calculated for Found 
CsH4O05Ca.2H20 (per cent). . 
Calcium 19.23 19.10 
Another sample of the salt was dried to constant weight at 
160°. 
Calculated for Foun 
CsHi05Ca.2H20 (per za 
Water of crystallization 17.31 17.30 
Calcium was determined in the anhydrous salt. 
Calculated for Found 
C4H405Ca (per cent). 
Calcium 23.25 23.32 
Citric acid was shown to be absent by means of the delicate 
distillation method of the author. Therefore, it is evident that 
roselle owes its pleasant acidity entirely to dextro malic acid. 
This is not confined to the calyx alone, but is distributed through- 
out the plant. The leaves contain about 1.25 per cent and the 
stems about 0.60 per cent, depending upon their age and location. 
The stems of the red variety also contain some coloring matter. 
It appears from these analyses that both stems and leaves contain 
sufficient flavoring material to render them suitable for use in 
connection with the calyxes except in those cases where it is 
desired to obtain a brilliantly colored jelly or jam. A compre- 
hensive examination was made of roselle with reference to its 
°Cir. U. S. Dep. Agr. Bur. Chem. (1911), No. 88. 
