Dry ice used to quick-freeze Sam Carter's blood.
Dry ice is a solid form of carbon dioxide. It's used primarily as a coolant.
History[]
In 1999, Teal'c, Dr. Janet Fraiser, Major Samantha Carter, and Colonel Jack O'Neill were infected with Ma'chello's Goa'uld killing organisms. Because Carter was the former host of the Tok'ra Jolinar of Malkshur, the organism exited her body. Since they had different blood types, to cure the others, Sam's blood after it had gone through a centrifuge, then dry ice was used to quick-freeze it. This made it so the rejectable parts of the red blood cells could be separated out. The rest was then safely given to the infected so they could get the protein marker she had left over from when she was blended. (SG1: "Legacy")