1889.] 



Presents 



249 



Both the grey india-rubbers yield a considerable ash when burnt. 

 The hard grey, as is apparent from its density, containing a large 

 percentage of inorganic matter. 



The following table gives the mean of all the experiments. 



Table showing the Physical Properties of three kinds of Vulcanised 



India-rubber. 



Description of 

 india-rubber. 



Density. 



Young's modulus. 



Simple rigidity. 



Statical. 



Dynamical. 



Statical. 



Dynamical. 



Eed 



1- 289 

 1 '407 



2- 340 



124 

 166 

 495 



195 

 217 

 500 



65 

 50 

 158 



80 to 127 

 57 



156 to 202 



Volume 

 elasticity. 



Viscosity. 



Limit of 

 stretching 

 of unit 

 length. 



Breaking 

 strain. 



Breaking 

 strain for 

 a square 

 inch of 

 unstrained 

 material. 



198,000 

 115,000 

 940,000 



13-74 

 2-578 

 7-725 



9-9 

 7-3 

 4-4 



about 

 8100 

 6400 

 4400 



about 

 820 

 820 

 820 



The units employed throughout this paper arte the inch, pound, 

 and second. 



The Society adjourned over the Whitsuntide Recess to Thursday, 

 June 20th. 



Presents, June 6, 1889. 



Transactions. 



Baltimore : — Johns Hopkins University. Studies in Historical 

 and Political Science. Ser. 7. Nos. 5-6. 8vo. Baltimore 1889. 



The University. 



Batavia : — Bataviaasch Genootschap van Kunsten en Weten- 

 schappen. Notulen. Deel XXVI. Anev. 3. 8vo. Batavia 

 1888 ; Tijdschrift voor Indische Taal-, Land- en Volkenkunde. 

 Deel XXXII. Anev. 5. 8vo. Batavia 1889; Nederlandsch- 

 Indisch Plakaatboek, 1602-1811. Deel V. 8vo. Batavia 

 1888. The Society. 



