==========================++=========================================== Zinc and iron may be in ||Lead, tin, copper, and calcium, if present, solution. Add bromine ||will be in the precipitate and residue. water to destroy hydrogen ||Fuse the mass in a porcelain crucible for sulfid and to oxidize the ||at least ten minutes with 2 grams each of iron, boil and add ammo- ||potassium and sodium carbonates and half nium hydrate in excess, ||as much sulfur. After cooling, boil with boil again and filter. ||water and filter. ---------------+----------++---------------------------+--------------- The precipitate|Filtrate, ||Residue. Add hydrochloric |The filtrate may will contain |when blue,||acid and boil as long as |contain tin. the iron and |proves the||hydrogen sulfid is given |Acidify with the phosphates.|presence ||off. A few drops of bro- |acetic acid, and |of nickel.||mine water will complete |if tin is pres- | ||the oxidation of the |ent a yellow | ||copper sulfid. Filter, and|precipitate of | ||add ammonium hydroxid in |stannic sulfid | ||excess to the filtrate. |will form. | ||When the filtrate is blue,| | ||it indicates the presence | | ||of copper. Acidify the | | ||filtrate with acetic acid | | ||and test for lead by | | ||adding potassium chromate,| | ||a yellow precipitate being| | ||formed when it is present.| ---------------+----------++--------------------------+---------------- |I. Heat to|| | |boiling || | |and add || | |potassium || | |ferrocya- || | |nid. A || | |white pre-|| | |cipitate || | |or turbi- || | |dity in- || | |dicates || | |_zinc_. || | ===============+==========++==========================+================ FISH SALT DRIED AND OYSTERS This kind of meat is often preserved with boric acid and borax. They may be detected by the method given under fresh and smoked meat. COLORING MATTER Sausages and other chopped meat preparations, together with corned meat that has been cured without saltpeter, are often treated with artificial coloring matter.