Addiction to crack usually occurs with four to six weeks; much more rapidly than with regular cocaine.Powder cocaine (cocaine hydrochloride) must be heated to a high temperature (about 197 °C), and considerable decomposition/burning occurs at these high temperatures. This effectively destroys some of the cocaine and yields a sharp, acrid, and foul-tasting smoke. Cocaine base/crack can be smoked because it vaporizes with little or no decomposition at 98 °C (208 °F), which is below the boiling point of water. Crack is a lower purity form of free-base cocaine that is usually produced by neutralization of cocaine hydrochloride with a solution of baking soda (sodium bicarbonate, NaHCO3) and water, producing a very hard/brittle, off-white-to-brown colored, amorphous material that contains sodium carbonate, entrapped water, and other by-products as the main impurities. The origin of the name "crack" comes from the "crackling" sound (and hence the onomatopoeic moniker "crack") that is produced when the cocaine and its impurities (i.e. water, sodium bicarbonate) are heated past the point of vaporization. Coca leaf infusions
Coca herbal infusion (also referred to as coca tea) is used in coca-leaf producing countries much as any herbal medicinal infusion would elsewhere in the world. The free and legal commercialization of dried coca leaves under the form of filtration bags to be used as "coca tea" has been actively promoted by the governments of Peru and Bolivia for many years as a drink having medicinal powers.
The blood received by the parasitic twin has already been used by the normal fetus, and as such is already de-oxygenated, leaving little developmental nutrients for the acardiac twin. Because it is pumping blood for both itself and its acardiac twin, this causes extreme stress on the normal fetus heart. Many T.R.A.P. pregnancies result in heart failure for the healthy twin. This twinning condition usually occurs very early in pregnancy. A rare variant of the acardiac fetus is the acardius acormus where the head is well developed but the heart and the rest of the body are rudimentary. While it is thought that the classical T.R.A.P./Acardius sequence is due to a retrograde flow from the umbilical arteries of the pump twin to the iliac arteries of the acardiac twin resulting in preferential caudal perfusion, acardius acormus is thought to be a result of an early embryopathy. Images of parasitic twins
Human
Animals
See also
Dipygus
Frank Lentini
Lakshmi Tatma
Lazarus and Joannes Baptista Colloredo
Rudy Santos
Vestigial twin

References
Further reading
Lebel, Robert Roger; Carlos Mock; Jeannette Israel; William Senica (June 1994). "Twin reversed arterial perfusion syndrome, acephalic presenting at full term". TheFetus.net. Retrieved 18 February 2013.