Crystalloid, definition

It is perhaps worth pointing out that every crystal is in fact defective, even if its only defect is that it has surfaces. However, if a crystal is only a ten-unit-cell cube, about half of the unit cells lie in the surface and thus have environments very different from those of the other half. The physical observation is that very small aggregates need not be crystalline, although they may nevertheless be perfectly structured. Mackay s proposal is to apply the name crystalloid to them. He offered the following definitions [133] ... 

Protein colloids contain larger molecules and have a longer intravascular residence time than crystalloids, but eventual fluid loss to the extravascular space does occur. Protein colloids, such as albumin and PPF, are prepared from pooled human blood and, therefore, carry with them a risk of transmission of viral infection or induction of anaphylaxis. The PPF is a 5% mixture (5 g of protein in 100 ml of 0.9% NaCI solution) of proteins that is osmotically equivalent to human plasma. The composition of the protein mixture is 83 to 90% albumin. Albumin typically is administered as either a 5 or 25% solution. By definition, albumin preparations must be composed of a protein mixture that is more than 90% albumin. Generally, PPF is favored over albumin for fluid resuscitation, because albumin appears to cause more interstitial edema. 

Endeavors to determine the electrochemical equivalent of colloids have not been very successful in most cases owing to the confused relations between the size of the particles and the charge. Sometimes it is quite impossible because the substance is partly colloid and partly crystalloid, e.g., Benzopurple, Congo red. Nevertheless, the amount of electricity on a definite amount of colloid has been determined. In all cases, however, where the particles migrate and are discharged at the electrodes, electricity must be transported. Although it is very small in comparison to that of solutions of electrolytes, owing to the comparatively small number of particles involved, it has been often determined in the case of hydrosols. 

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