330 T. V. SHCHERBA.KOVA 



Table 1. Particle composition of clay suspension in per cent 



In addition, investigations were carried out with clay suspensions prepared 

 from light clay (kaolin). 



Measurements were carried out with a light beam intensity equal to 2.5 

 Ivimens; for samples of clay suspensions with y = 1.013, 1.026 and 1.045 

 measurements were made with different light intensities. Variation of the 

 light intensity was achieved by interposing a photographic film ^vith different 

 degrees of blackening between the light source and the sample. The attenuation 

 coefficient of the film had been determined beforehand. 



From the results of the measurements curves of the value of the transmit - 

 tance T as a function of the thickness h of the layer of clay suspension were 

 constructed for various wavelengths A of light (Fig. 1). 



1- 



100 



7-=l-02 



^ 



1-04 



^=1-06 ;k=I-IO 



1-0 



0-1 0-3 0-5 0-7 0-9 l-l 1-3 1-5 1-7 0-1 0-3 0-5 0-1 0-3 



h. mm h, mm h. mm 



Fig. 1. Dependence of attenuation of light on specific gravity y of the suspi 

 thickness h of the layer and wavelength ?i of light. 



0-1 0-3 

 h, mm 



;nsion, 



It can be seen that clay suspensions are indeed very turbid media and even 

 in thin layers transmit very little light. Thus, even when the thickness 

 of the layer of clay suspension is only some tenths of a millimetre the trans- 

 mittance of the light is only about 1 per cent. 



