PHYSICAL AND CHEMICAL PROPERTIES. PARTS IV, V. 191 
the physical and chemical properties of the different products 
examined demonstrated the accuracy and usefulness of this test. 
As stated, we believe that in the hands of an expert it gives 
more definite and reliable information regarding the constancy 
of strength and volume than the usual 28-day or even 3- or 
6-month tests. However, there is one undesirable feature to 
this test; namely, that it requires considerable experience and 
ability correctly to interpret the significance of the phenolate 
crystals formed on the microscopic slide. Therefore, in order 
to make this test generally practicable and universally depend- 
able, it must be simplified or made quantitative. Certainly, 
its possibilities and importance warrant much more extended 
research in this direction than we have had opportunity to 
accomplish. 
