Its presence may some times be determined by making the usual starch test. A large quantity of starch is normally present in apples, but is less as they ripen, and finally disappears in the ripened fruit. There is no starch, or only a mere trace, in small fruits even when green. It is readily seen that if the juice is taken from green apples that there will be starch found in the artificial jelly or jam, though its absence does not prove the absence of cider. Make the starch test as follows: STARCH IN JELLIES, JAMS, AND SUCH PRODUCTS Make a solution of the jelly or jam and destroy the color by heating nearly to the boiling point and adding dilute (1 : 3) sulfuric acid and potassium permanganate until the color is destroyed. This treatment does not affect the starch, and when cool add iodin, preferably potassium iodid-iodin (potassium iodid, 0.4 gram; iodin, 0.1 gram; water, 20 cc.). If a great quantity of starch is present an almost black precipitate will be formed. Smaller amounts give the usual blue color. Whenever starch is found to be present, it is best to make a microscopical examination in the case of jams and marmalades. If the starch is normally present the grains will be seen within the cell walls after the iodin treatment. Starch is nearly always present in the apple and some other fruits, so unless it is present in jelly and such products in considerable quantity it is not likely that it was added. GELATIN IN JELLIES _Henzold Test._--Add water to some of the jelly and boil for a short time, filter and treat the filtrate with an excess of a 10 per cent solution of potassium bichromate and boil again. After cooling add 2 or 3 drops of concentrated sulfuric acid. A white flocculent precipitate forms if gelatin is present, and it gradually collects in a lump at the bottom. _E. Beckmann’s Method._--Treat the jelly with 95 per cent alcohol and wash the precipitate with alcohol to free it from the sugar, then drive off the alcohol by heating. Add a very little water to the residue and neutralize the extract with calcium carbonate. Then add formalin and evaporate to dryness. By this treatment gelatin is rendered insoluble. Pure fruit jellies have only 1 to 2 per cent of insoluble precipitate, while those jellies in which gelatin is used have 70 to 86 per cent of insoluble precipitate. AGAR AGAR Boil the sample with 5 per cent sulfuric acid. Add a crystal or two of potassium permanganate, and wait till it settles, and examine the sediment for diatoms with a microscope. Their presence shows the use of agar. HEAVY METALS TIN, ZINC, LEAD, AND COPPER _A. H. Allen’s Method._--(See test for heavy metals under canned meat.) ARSENIC