Electrolytes possess the power of coagulating solutions of colloids such as albumen and arsenious sulphide.
The Hevea product is obtained annually by tapping the trees and coagulating the sap over a smoky fire, but the caucho is procured by felling the tree and collecting the sap in a hollow in the ground where it is coagulated by stirring in a mixture of soap and the juice of a plant called vetilla.
Metaphosphoric acid can be distinguished from the other two acids by its power of coagulating albumen, and by not being precipitated by mag nesium and ammonium chlorides in the presence of ammonia.
The rubber is obtained by incising the stems of the vines and coagulating the latex by exposure, by admixture with acid vegetable juices or by heating.