Adsorption Properties of Hair 342 them.” The more highly energetic nature associated with particularly dry fibers was believed to represent adsorption in pores, lesser energy was released as the pores became filled, while little heat evolution was attained as higher water content led to solution- like properties. This same idea was later further formalized by Pierce,9 while Speakman10 extended this thinking into water adsorption by wool. These ideas were eventually abandoned as the concept of multilayer adsorption was popularized by Brunauer, Emmett and Teller.11 In short, an adsorbed polar water molecule itself serves as an adsoption site for additional molecules, as shown in Figure 8. Therefore, higher energies are associated with so-called “localized water” adsorbed at hydrophilic sites on the protein, while progressively lower energies are associated with each subsequent multilayer of bound water. Figure 7. Type II isotherm obtained from the combination of Type I and Type III isotherms