Scientific Intelligence, — Geology. 173 



the gas might be got rid of by means of a ventilator, whicli 

 should propel it into a gallery of transport, in which the current 

 of air was so strong, that it sometimes blew out the lamps of the 

 workmen. The engineers supposed that the gas, instead of hav- 

 ing been forced out of the mine by the current of air, was forced 

 only into some old abandoned workings which were situated at 

 the extremity of the gallery of transport, behind pillars and 

 walls, and some rubbish ; and that it was there ignited, owing to 

 the falling down of a part of the roof of this cavity, whereby a 

 great quantity of the gas was suddenly expelled, or possibly 

 owing to some of the workmen having taken a lamp into it. 

 However this may be, the gas has begun to shew itself in the 

 works, in the neighbourhood of the fault of the pits of St Louis ; 

 and this circumstance recurring frequently in the mines, it be- 

 comes important to recommend it to the peculiar attention of 

 miners, and to point out to them the means of its prevention." 



3. Analysis of a Clay Ironstone ^forming a bed twelve inches 

 thicTc, in the Coal Formation at War die, to the westxvard of New- 

 haven, near Edinburgh ; by William Gregory, Esq. M. D. — 

 No. 1. from a depth of twenty fathoms and five feet, contains in the 

 calcined state, as given to me in 100 parts. Matter insoluble in 

 acid (sand), 19 6 ; Peroxide of iron, 72 5 ; Alumina (clay), 3 5; 

 Lime (a trace), 0; Moisture and loss, 4 4; = 100. — No. 2. 

 from a depth of twenty-six fathoms and four feet, contains in a 

 calcined state in 100 parts. Insoluble matter, 37 8 ; Peroxide of 

 iron, 5Q 4 ; Alumina, 2 5 ; Lime (a trace), ; Moisture and 

 loss, 3 3; = 100. — No. \ when calcined contains, therefore, 

 about 50 per cent, of pure iron, calculated in the metallic state, 

 and No. 2, 40 per cent, nearly. — No. 3, in its natural state con- 

 tains in 100 parts, Insoluble matter, 19 3 ; Protoxide of iron, 

 45 9 ; Alumina, 1 5 ; Water and loss (a trace of lime) carbon, 

 &c. 33 3 = 100. — The metallic iron here is 32 2 per cent. ; the 

 reason of the difference is, that by the calcination a quantity of 

 water was expelled, so that in numbers one and two, the quan- 

 tity of iron is increased in proportion to the weight of the mine- 

 ral analyzed. All the ores are remarkably good, and there can 

 be no doubt that, with the addition of lime and other neceasary 

 fluxes, they will work admirably. I have scarcely seen any ores 

 of the coalfield containing so much as 45 per cent, protoxide ; 



