Categories of Batel/Nullification
Categories of nullification of non-kosher ingredients:

• Never batel.
• Batel b'shishim when the non-kosher substance is less than 1/60th of the total volume of the food.
• Batel barov when the non-kosher substance is less than 1/2 of the total volume of the food.

When Can a Non-Kosher Substance Be Nullified in a Mixture?
Whether a non-kosher substance can be nullified in a mixture depends on 3 factors:

• Whether the owner is Jewish;
• Whether the intended eaters are Jewish; and
• Whether the non-kosher substance was added intentionally as non-kosher.

If the answers to all three cases is yes, the food is never batel.

Food “Nullified in 60 Parts”:
Accidentally Adding Non-Kosher to Kosher Food 

• Less than 1/60 of the volume of the whole.
• Mixed in and not lying on the surface.
• Not intentionally added by a Jew.
• Not listed in “Foods that Never Become Nullified” (below).

Min b'Mino
Substances are only batel when they are similar (“min b'mino”). The substances must be the same type, have the same taste, and have the same appearance (the eater cannot identify them as being different).
Note In such situations, it would be batel barov from Torah (d'oraita) but batel b'shishim (1/60^th) by rabbinical order (d'rabanan).
Example A piece of non-kosher meat is mixed in with kosher meat of more than 60 times the volume of the non-kosher piece. The non-kosher meat is batel b'shishim.
Note As a practical matter, this can only apply to ground meat.
Counter Example Non-kosher chocolate syrup or a non-kosher flavored extract mixed into milk or other liquid or onto a solid would NOT be min b'mino even though both are liquids, since their appearances, flavors, and substance are different.

Too Thin To Make Non-Kosher

• Yayin Nesech
  Wine that has been offered to a pagan god or used for idolatrous purposes (yayin nesech) is forbidden in any amount!
• Mixtures of Milk and Meat
  Mixtures of milk and meat are not ever batel if they were cooked together.
  ExceptionBatel in 1/60^th if:
  • You cannot identify either substance AND
  • The mixture is liquid in liquid or solid mixed with solid.

Examples: Milk from a pig mixed with milk from a cow; ground kosher meat mixed in with ground non-kosher meat.

• Chametz

• Jew Intentionally Adding Non-Kosher Item

• Unflavored or Flavored Non-Kosher Ingredient
  
  Non-Jew Adds Unflavored Non-Kosher Ingredient
  

  Situation A non-Jew adds a non-kosher ingredient that has no flavor. 
  Status The non-kosher ingredient is nullified if less than 1/2 of the total (it does not need to be less than 1/60th--batel ba'shishim).

  
  Non-Jew Adds Flavored Non-Kosher Ingredient

  Situation A non-Jew adds a flavored non-kosher ingredient even if to impart flavor.
  Status The non-kosher ingredient is nullified in 60 parts (batel ba'shishim).
  

  Note If a Jew had told the non-Jew to add the ingredient, the mixture is non-kosher, just as if a Jew had added it. 
• Stam Yeinam Added to Water
  Situation A non-Jew adds—to water--stam yeinam (uncooked/non-mevushal) wine that has been handled while open by anyone other than a shomer-Shabbat Jew.  
  Status As long as the wine is less than 1/7th of the final volume, the mixture is kosher. 

  Note For mixtures with liquids other than water, consult a rabbi. 

• Essential Additives

• Food Bought by the Piece

• Important Food

• Permissible in Future (Davar SheYesh Lo Matirin)

• An egg laid on Shabbat will not be nullified by being mixed with eggs laid before Shabbat.
• Matza made of chadash flour will not be nullified by being mixed with matza made from yashan flour.

• Whole Insects

• Frozen or raw chopped or ground vegetables or spices may be considered kosher even without supervision.
  Reason We assume that any bugs in the food would have gotten partly chopped or disintegrated and therefore nullified.
• If a recipe calls for chopping or grinding herbs or vegetables, you may do so without first checking them for bugs.
  Note However, if you know there are bugs, you may not chop the food for the purpose of making the bugs nullified:  You must still check for insects before cooking or eating the food and if you see any bugs, you must remove them.

When a person dies on Shabbat or a Jewish festival, a watcher (shomer) should still be present until burial, even if there will be a delay of several days.
 

You do not need to stand up for old people (as a form of honoring them) unless the old person is over 70 years old and is shomer mitzvot. This applies to women, too, if they are 70 years old or more and are shomrot Shabbat.
 

It is forbidden to shower on Shabbat.

Taking care of many of our physical needs before Shabbat begins allows us to enhance our physical rest and emphasize our spiritual nature on Shabbat.
To prepare, we make or buy the food we will need for Shabbat, clean the house, and put it in order.  The custom is to shower or bath especially for Shabbat.
Before sunset on Friday, we turn on whatever lights we will need during Shabbat so that our homes are well lit. We leave the lights on until Shabbat is over (or we set timers to regulate when the lights go on and off since we cannot be involved with controlling them).
 

The International Dateline (IDL), which is 180 degrees away from Greenwich, England, crosses the Pacific ocean from north to south and divides a region of safek/doubt as to which day is Shabbat. This region's eastern boundary is a line 180 degrees east of Jerusalem, which lies between Hawaii and the US mainland; the western boundary is east of Shanghai. All countries in this region of IDL safek/doubt are island countries.
 
In a region of doubt, such as Tasmania, keep normal Shabbat (Shabbat d'rabanan) on local Saturday and keep Shabbat d'oraita on:

• West of mainland USA, but
• East of the IDL, and
• Not attached to the mainland.

• West of the IDL, but
• East of Shanghai, and
• Not attached to the mainland.

Note In all cases, you must still observe regular Shabbat on Friday night/Saturday.
Situation
You are in a place near the International Dateline (IDL) in which you are not sure which day of the week it is halachically: Shabbat or, if you are east or west of the IDL, Friday or Sunday.
What To Do
On the Friday or Sunday in question, there is no shvut (d'rabanan prohibitions, including muktza), so you may do all melacha d'rabanan WITHOUT a shinui. You may:

• Ask or tell a non-Jew to do anything, including a melacha d'rabanan or d'oraita.
• Ride in a cab or car driven by a non-Jew.

• Use electricity--except for heat or light—including turning on a fan or air conditioner (heat and light are forbidden by the Torah).
• Use the telephone. (Using a cellphone may be permissible--ask a rabbi).

• Carry from a private domain (reshut ha'yachid) to another private domain, even through a public domain (reshut ha'rabim); but you may not stop walking in the public domain and you may not put the object down in the public domain unless you use a shinui.
• There is no practical way to light candles, even using a shinui, but a non-Jew may light them for you and and you may say the blessing on the candles.
• Swim, surf, scuba dive, climb, and play all games that do not use melacha. You may not wring out clothes and if you are swimming or scuba diving, your swimsuit or wetsuit must be clean.
• Walk any distance (there is no techum Shabbat d'oraita).
• Kinyan. You may acquire items.

• Fly, including check in and getting on plane if:
  • The pilot is non-Jewish, and
  • You don't do any melacha d'oraita (including any writing) without a shinui.
• Use a computer if it automatically goes to sleep after less than 24 hours of not being used.
• Shower. However:
  • You may not use an “instant on” hot water system in which the water is heated as you use it; you may only use the hot water if it has a holding tank.
  • You may use only liquid soap; hard soap is forbidden.
• Ingest medicine (but you may not smear it on skin).
• Use some make up, such as rouge, mascara, eye shadow. You may not use lipstick.
• Open a refrigerator with light (and all other psik reisha d'la neicha lei).

• You may buy necessities on Friday or Sunday as long as:
  • The store owner is not Jewish (or if he/she is Jewish, does not write or print a receipt),
  • You do not write, and
  • There is no reshut ha'rabim.

You may also do melacha d'oraita if:

• You use a shinui (non-normal way of doing that action--this is forbidden d'rabanan on Shabbat but is allowed on the Friday or Sunday in question), OR
• Two or more people do the melacha together.

 
D'oraita, you may not:

• Cook food.

• Turn on lights (but you may turn them off).
• Carry from domains.
• Boneh – building any permanent structure.
• Write two or more letters of the alphabet.
• Drive--there is no practical way to drive using a shinui.
• Shave--there is no practical way to shave using a shinui.
• Use toothpaste (but you may use tooth-cleaning powder).
• Use skin cream--you may dab it on without smearing it.

However, you may do these following actions with a shinui on the Friday or Sunday in question, as follows:

• Cook food. You must put food in the cooking utensil first, then turn on the heat with shinui. You may turn off the heat even without a shinui.
• Turn on lights (such as with your elbow).
• Stop along the way when carrying from a private domain (reshut ha'yachid) to another private domain, even through a public domain (reshut ha'rabim). As a shinui, you may carry the object in your mouth (as long as it is not food), etc.

Note Carrying something in your pocket is NOT a shinui.

• Tear paper (such as putting toilet paper across knees and moving the knees apart).
• Write (such as with the opposite hand).

Flying East From Australia on Sunday If You Cross IDL from Friday into Saturday

You may add personal requests to the amida on weekdays (not Shabbat or Jewish festivals) in these prayers:

• For livelihood:
  • In the amida's 9^th paragraph (bareich aleinu), between mi'tuvecha and u'vareich shnateinu.
• For a general request:
  • In the amida's 16^th paragraph (shema koleinu), before ki ata shomei'a.
  • Even better, just before saying yihiyu l'ratzon.

 

Restrictions during the Nine Days before Tish'a b'Av are the same as for Three Weeks, plus:

• You may not eat meat or drink wine.
  Exceptions

  1. You may drink wine on Shabbat (but not on Rosh Chodesh Av or erev Shabbat.)
  2. You may drink wine for havdala (but ideally give the wine or grape juice to a child between ages 6 and 10).  
  3. You may eat meat or drink wine at a brit, siyum, or pidyon ha'ben.
• You may not wear freshly laundered clothes, or wear or buy new clothes.

• You may not wash yourself for pleasure.
  Note Showering or bathing to clean one's soiled body is permitted (except on Tish'a b'Av).  So you may bathe or shower during the Nine Days if you are dirty, sweaty, or smelly.
• You may not do any activities that involve luxury.
• You may not say she'hecheyanu except on Shabbat.
  Note Therefore you should not buy new fruits or new items that you will enjoy during the Nine Days.  But if you DO eat a new fruit or buy something new, you must say she'hecheyanu anyway.