Page:Popular Science Monthly Volume 78.djvu/602

592 colloid solutions. Especial value is placed upon electrical methods of investigating colloids. A proper distillation plant serves exclusively for providing the purest so-called conducting water. There is an apparatus after Kohlrausch with various electrode vessels for the estimation of the electric conductivity of electrolytes. For the determination of ion concentration in solutions there is a complete contrivance made of brass with electromotor power and having concentration chains with an elongated measuring bridge and a mirror galvanometer with reading telescope. The mechanisms for the calculation of the electric charge of colloids are technically perfected. The conducting apparatus of Landsteiner and Pauli was tested in an investigation

on toxins. Here each colloid, separated from the remaining fluid by the electric permeation, arises and can be easily isolated and tested. Since only the alternating current is found in the institution, two batteries, one of 200 and one of 75 volts, are employed to produce the current. In addition there are the necessary normal and precision thermometers, the instruments for the determination of the freezing point and the coagulation point, precision rheostats, Weston's volt- and ampere-meter, polarimeters and numerous small auxiliary apparatus.

The large general laboratory has fifteen working places fitted with all the usual optical and histological apparatus and reagents. The necessary conditions for the study of the influence of mechanical agencies are enough light, as little dust and infectious material as possible