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THE POPULAR SCIENCE MONTHLY 



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 appa- 

 ratus after Kohlrausch with various electrode vessels for the estima- 

 tion 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 read- 

 ing telescope. The mechanisms for the calculation of the electric 

 charge of colloids are technically perfected. The conducting appa- 

 ratus of Landsteiner and Pauli was tested in an investigation 



FiQ. 9. Cement Basins in the Garden. 



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 agen- 

 cies are enough light, as little dust and infectious material as possible 



