An emulsion comprising: water; hydrophilic particles; and hydrophobic particles; wherein the hydrophilic and hydrophobic particles form shells encapsulating a gas that are suspended in the water, said shells comprising an external layer of hydrophilic particles and an internal layer of hydrophobic particles adjacent to the layer of hydrophilic particles.
RELATED APPLICATIONS
The present application is a divisional application of U.S. application Ser. No. 10/053,401 filed on Nov. 9, 2001 now U.S. Pat. No. 6,808,715, the disclosure of which is incorporated herein by reference.
