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LXII. Concerning Accidental Double Refraction in Liquids. 

 Bu J. E. Almt, A.M., Fellow in Physics, University of 

 Nebraska, Lincoln, Nebraska, U.S.A.* 



THE question whether the condition of strain which occurs 

 in a mass of liquid, deformed by friction, gives rise to 

 double refraction of light, as does such condition in the case 

 of solids, has frequently been raised. 



Mach f, Maxwell %, Quincke §, and Kundt || have made 

 observations of the phenomenon in liquids of different types : 

 Mach with extremely viscous substances, semi-solids ; Max- 

 well with Canada balsam ; and Kundt with the more nearly 

 fluid liquids, such as oils and solutions of gelatine, glue, col- 

 lodium, and balsam. 



Of Kundt's conclusions the following are significant : — 



1. " The magnitude of the internal friction (viscosity) of 

 liquids is not primarily sufficient to determine the occurrence 

 of double refraction." 



2. The liquids and solutions which give double refraction are 

 oils, or belong to that class of substances known as colloids. 



3. Solutions of crystalline substances, without exception, 

 give no double refraction. " However, it is not to be in- 

 ferred," he adds, " that with improved means of investigation, 

 the effect may not be obtained with solutions of crystalline 

 substances/' 



It has been the purpose of this work to find whether double 

 refraction may be shown in liquids not oils, or with solutions 

 of crystalline substances. And, while double refraction has 

 not been obtained in either case, it has been possible to extend 

 the limit of accuracy with which the subject has been tested 

 by a factor of over 3 x 10 2 in case of water, and by 10 2 in the 

 case of solutions of crystalline substances. 



Apparatus. 



The apparatus used for producing the condition of strain 

 consists of two brass cylinders, each 10'8 cm. in diameter, 

 15 cm. in length, mounted the one above the other, their 

 axes parallel, the surfaces of the two being about 0*4 cm. 



* Communicated by the Author, 

 t Mach, Optic- Akustisch Versuche. Prag, 1873. 

 % Maxwell, Proc. Roy. Soc. xxii. p. 46 (1874). 

 § Quincke, Wied. Ann. x. p. 53(5 (1880). 



|| Kundt, Pocrg. Ann. cliii. p. 10 (1874) ; and Wied. Ann. xiii. p. 110 

 (1880). 



