129 



between plasma and glass is (lie same. This cuvette is placed in 

 another one of special construction, which acts as a thermostat, is 

 filled with water and is heated electrically. 



The measurement proceeds as follows: 



The cuvette is placed in the thermostat so as to make the light 

 of the lamp reach the thermo-battery II and [)ass through llie plasm. 

 By its side, in the same thermostat, stands a test-tube containing 

 Ih c.c. Vs 7o CaCl.,. The extinctionmeter is "adjusted". Then follows 

 a 20 minutes' wait, after which the plasm and the CaCl^ will be 

 of the temperature of the thermostat and the galvanometer will be 

 completely quiescent and in the zero-position. The work-room is 

 made semi-daik and from this moment photogra[)hical readings are 

 taken from the galvanometer A registering instrument is used that 

 is moved by a perfectly reliable clockwork. 



After some njoments the 1| c.c. 7a 7o t^aCl^ are added to the 

 plasm, the whole mixture is rapidly stirred for half a minute with 

 a sterile glass rod and is then left to itself. The galvanometer then 

 traces on the sensitive paper of the registering instrument the 

 "turbidity-curve". 



Fig. 1 is a faithful reproduction (natural size) of such a curve, in 



Fig 1. 



