What is the difference between alum( like salt) and ammonium alum (like baby powder)?

also, what is ammonium alum used for? i bought it in the supermarket. all the label says is ';do not ingest'; it doesn't have uses or directions on it. cal someone please help me?? thanks a bunchWhat is the difference between alum( like salt) and ammonium alum (like baby powder)?
What is alum?


Alum is a salt that in chemistry is a combination of an alkali metal, such as sodium, potassium, or ammonium and a trivalent metal, such as aluminum, iron, or chromium. The most common form, potassium aluminum sulfate, or potash alum, is one form that has been used in food processing. Another, sodium aluminum sulfate, is an ingredient in commercially produced baking powder. (Have you never noticed the faint metallic taste in baking powder? It comes from the alum.)





The potassium-based alum has been used to produce crisp cucumber and watermelon-rind pickles as well as maraschino cherries, where the aluminum ions strengthen the fruits' cell-wall pectins.





Alum is approved by the U.S. Food and Drug Administration as a food additive, but in large quantities 鈥?well, an ounce or more 鈥?it is toxic to humans. As a result, efforts have been made and are being made to wean us of our alum dependency. The U.S. Department of Agriculture says that if good quality produce and modern canning methods are employed, there is no need to use alum to bolster the crispness of our pickles and cherries. In any event, the department says, even if alum is used to soak the pickles, it should not be used in the final pickling liquid


http://www.ochef.com/1080.htm





Ammonium alum (NH4Al(SO4)2路12H2O) or ammonium aluminium sulfate dodecahydrate is a white crystalline double sulfate of aluminium, used in water purification, in vegetable glues, in porcelain cements, in natural deodorants and in tanning, dyeing and in fireproofing textiles.The pH of the solution resulting from the topical application of ammonium alum with perspiration is typically in the slightly acid range, from 4 to 5. It is a popular deodorant because of its high availability and low cost.


http://en.wikipedia.org/wiki/Ammonium_al鈥?/a>





Harmful if swallowed. May cause irritation. Avoid breathing vapors, or dusts. Use with adequate ventilation. Avoid contact with eyes, skin, and clothes. Wash thoroughly after handling. Keep container closed.


Harmful if swallowed. May cause irritation. Avoid breathing vapors, or dusts. Use with adequate ventilation. Avoid contact with eyes, skin, and clothes. Wash thoroughly after handling. Keep container closed.


FIRST AID: SKIN: Wash exposed area with soap and water. If irritation persists, seek medical attention.


EYES: Wash eyes with plenty of water for at least 15 minutes, lifting lids occasionally. Seek Medical Aid. INHALATION: Remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen


INGESTION: If swallowed, induce vomiting immediately after giving two glasses of water. Never give anything by mouth to an unconcious person.


http://www.sciencestuff.com/msds/C1175.h鈥?/a>