1. Some existing types of rennet tests are briefly reviewed.

2. A viscosity type of rennet test is described and results from its use are given.

3. A mathematical treatment of the problems involved is given, which leads on to

4. Construction of graphs showing progressive variation in “Dying away of amplitude”, “Logarithmic decrement” and “Viscosity coefficients” of milk under the action of rennet. Since viscosity determinations on liquids and gases have been commonly carried out with a disk type of viscosimeter, such a type is now introduced and similar graphs constructed from observations during its use. A close similarity in graphs to those furnished by the cylinder type of viscosimeter is obtained. The cylinder type of apparatus, we find, is more convenient in use with milk in reference to rennet action.

5. Arising from the graphs a more precise method of terminating a rennet test with the present type of apparatus is indicated.