77 



Ordinary Meeting, January 23rd, 1872. 



E. W. BiNNEY, F.RS, F.G.S., President, in the Chair. 



The President exhibited to the meeting a large crystal 

 of Selenite, of an irregular form and eight inches in length, 

 given to him by Mr. Taylor, of Stretford. That gentleman 

 informed him that it was from the mud which had been 

 dredofed out of the Suez Canal. When the mud came out 

 of the dredge there was no appearance of crystals, but on its 

 drying and being afterwards broken up, they w^ere found in 

 the mass. The President said that he had noticed the for- 

 mation of similar but smaller crystals of selenite in the clay 

 taken out of the London and North Western Railway 

 Tunnel during its formation through Primrose Hill. When 

 the clay was first excavated there was no appearance of 

 crystals in it, but after it had been exposed to the weather 

 for a few months, on fracturing the clay these were found 

 dispersed throughout its mass. He had also found crystals 

 of selenite in the till or boulder clay at Egremont on the 

 Mersey and at Blackpool; and the crystals, from their 

 sharp edges, showed that they had been formed in situ, 

 and had not come from a distance as many of the stones 

 in the deposit had undoubtedly done. He had also seen in 

 coal mines the formation of small crystals of selenite nearly 

 an inch long in a few weeks. In this case their formation 

 was evidently due to water charged with carbonate of lime 

 coming into the shaft from the overlying drift beds and 

 finding its way down into the workings, and there mixing 

 with water containing sulphate of iron derived from decom- 

 posed iron pyrites ; the sulphuric acid of the iron going to 

 Peoceedings — Lit. & Phil. Soc. — Vol, XI. — No. 8. — Session 1871-2. 



