Dr Reid read a notice by the Rev. Edward Craig, of some modes which he had adopted for examining by the microscope, the phenomena of chemical action, by means of which, the most minute changes of appearance attendant on the contact of the smallest visible quantities of substances may be observed. The method was described to be:

1. The laying two or more substances on two thin flat plates of glass, and bringing them in contact with each other; so that the whole matter is spread in one thin level between the two glasses; and the several processes of union, decomposition, and crystallization may be accurately watched in a field of view of of an inch.