101 



the flint being organic the conditions of its structure would materially aid 

 in its disintegration. 



Dr. Matthevvs mentioned the circumstance that Wedgewood saw a farrier 

 drop hot flints into water in order to be able afterwards to powder them, 

 and that this was the origin of their use in china making ; also that simple 

 exposure to the weather was all that was required to disintegrate 

 granite, the result being the formation of china clay. He should like to 

 ask what was the chemical difference between flint and quartz, seeing that 

 quartz would polarize and flint wo aid not ? 



Mr. Hawkins Johnson said it was not strictly correct to say that flint did 

 not polarize ; glass and other colloids would not, but flint itself would, that 

 was if it wa3 examined with cros3el prisms, it would restore the light ; but 

 it would not show colour as quartz did. Organic silica, such as sponge 

 spicules, did not polarize. 



Mr. Waller said that when he made use of the term " polarize," he meant to 

 express the difference which there was between the two substances — quartz 

 giving those brilliant colours which they were so well acquainted with ; he 

 had mentioned, however, that flint was susceptible to polarized light. The 

 matter was one which he thought wanted more study, as there were other 

 kinds of silex which certainly did polarize, but which did not belong to the 

 chalk flints, and which could not be classed with the quartz. 



The thanks of the meeting were unanimously voted to Mr. Waller for his 

 paper. 



The proceedings terminated with the usual Conversazione, at which the 



following objects were exhibited . — 



Hipperio acid in arabin ... ^ ... ) the p resident# 



Bichromate of potassium in arabin ... j 



Cuticle of Lavender leaf, stained, showing^ ,, « w . , 



. ' ° > Mr. F. W. Andrew. 



stellate and branched hairs ... ) 



Fangs of Centipede, showing tuberculated| ^ ^ E Freeman 



poison glands... ... ... j 



Foraminiferafrom Teneriffe ... ... Mr. H. F. Hailes. 



Lophopus cystallinus, from Epping Forest ... Mr. J. D. Hardy. 

 Nelson's Flaked Gelatine, polarized ... Mr. T. S. Morten. 



Eyes of a My gale, a reputed bird-catching") 



spider ... ... ... ) 



Attendance — Members, 55 ; Visitors, 5. 



February 10th, 1882.— Conversational Meeting. 



The following objects were exhibited : — 



Larva of Corethra plumicornis, ^ inch objec- - ) q^v, p -a f 

 tive ... ... ... ... ) 



Section of Oat ... ... ... ... Mr. F. W. Andrew. 



Section of shell of Pinna ing ens ... ... Mr. W. R. Browne. 



My mar pulchellus, female, the Battledore-") -, _ _, , 



winged Fly ... j 



Journ. Q. M. C, Series II., No. 2. i 



