216 



and then put on the finishing coating afterwards, when the slides might be 

 ornamented to any extent without difficulty. 



Mr. Waddington read a paper " On the use of ' Arabin ' or perfectly- 

 pure Gum Arabic'' for attaching Diatoms, &c., in mounting. 



Mr. Borrer said he had used Arabin himself, and found it to be all that 

 Mr. Waddington had described it. Its chief merits were its great trans- 

 parency and the remarkable readiness with which it absorbed moisture, 

 and set again afterwards. 



Mr. Ingpen inquired what was its refractive index, and what was the 

 effect of the slight wave which collected round the sides of a small object 

 placed upon it ? 



Mr. Borrer said he was not able to state the refractive index ; but he had 

 not observed any effect whatever arising from its collection round the edge 

 of an object with any kind of illumination. 



Mr. Ingpen said that in mounting Diatoms it was often necessary to bake 

 the balsam so as to get it at its highest refractive index, and when Diatoms 

 were fixed down with ordinary gum, the gum showed as a bright disc. Did 

 Arabin show this, or did it remain quite transparent after heating with the 

 balsam ? 



Mr. Borrer said that Arabin would stand the heat of an ordinary spirit 

 lamp for eight hours, and no inconvenient effects occurred with any heat 

 which would practically be applied in mounting. 



Votes of thanks to the authors of the papers were unanimously carried. 

 Announcements of excursions, &c., for the ensning month were made, 

 and the proceedings terminated with the usual Conversazione, at which the 

 following objects were exhibited : — 



Papillaa in Tongue of Mouse, polarized 

 Stem of Thistle 



Chrysopa perla, the Lace Wing Fly (un- 

 mounted), showing thepygidium 

 Foraminifera from Dogs Bay, Ireland," 



mounted in wax cells in illustration of )■ Mr. H. Morland. 

 his paper 

 A series of specimens of Stained Leaves, 



pre^Dared by Dr. Hunt, of Philadelphia, J> The Club Microscoiic. 

 in 1872, lent by Mr. J. Stewart 



Attendance — Members, 55 ; Visitors, 7. 



September 10th, 1880. — Conversational Meeting. 



The following objects were exhibited : — 



Parasite and eggs found on leaf of Scarlet-"^ M- F W A 1- 



runner ... ... ... ) 



Specimens of Uafnarfiordite, a Lava from) ,j- ,, ,, 



Iceland ... ... ... ) 



Head of Gad-lly, IkcniatojKda iluvialis,') ,. 



iihowiiig brilliant eye... ... ) 



