184 TEAR-BOOK OF FACTS. 



removing the cork (which was much softened), strong acid fumes 

 escaped. I put in a few drops of alcohol, which absorbed the 

 vapours. I then sealed it, put it into the trunk again ; but on 

 looking at it again a day or two before it took fire, the yellow vapour 

 had again collected : but as I had not heard of spontaneous com- 

 bustion having ever taken place, I put it back, and the next thought 

 of it was caused by the report, as above stated. What caused the 

 cotton to ignite ? Is this an isolated case ? I have had other sam- 

 ples develope reddish- yellow vapours ; and as it is good for nothing 

 in that state, I have thus far destroyed it before it destroyed me." 

 The Editor of the journal named, in corroboration of his Correspon- 

 dent, states that he once purchased a bottle of gun-cotton prepared in 

 Paris, which, as soon as the cork was removed, emitted fumes of 

 nitric acid, and would, he believes, have ignited if it had not been 

 at once plunged into water. 



FIRE-DAMP IN COLLIERIES. 



Captain E. B. Hunt has read to the American Association a 

 paper upon the Explosions of Fire-damp in Collieries. He showed 

 that the Davy-lamp had been proved to be unsafe when exposed to a 

 current of gas. fie recommends the substitution of coal-gas, manu- 

 factured at the surface and near the mouth of the mine, and forced 

 down in pipes, with such gauze safeguards as may be necessary. 

 The advantage of this would be the substitution of a system of 

 lighting, under the care of a responsible person, for dangerous lamps 

 in the hands of the careless and ignorant. Professor Rogers sug- 

 gested that a very powerful Voltaic light might be used at some 

 point, which, by a series of reflectors, should illuminate the mine. 

 Both he and other gentlemen showed the great danger of employing 

 illuminating gas ; although Mr. Ilockwel), of Norwich, who gave a 

 variety of interesting information upon the subject of mines, showed 

 that the system has been employed, under certain circumstances, in 

 some parts of mines abroad. 



GUANO. 



We derive the following items respecting this important manure 

 from an interesting paper recently presented to the French Academy 

 of Sciences by M. lioussingault. The deposits of Guano (hnuno de 

 pajoro) extend from the 2nd to the 21st degree south latitude along 

 the coast of Peru. Those which lie beyond these limits are much 

 poorer in ammoniac^ compounds than the former, and are not, 

 therefore, equal to tnem in value. Guano is generally found depo- 

 sited on small promontories or on dill's ; it lills up crevices, and is in 

 general to be found in those places where the birds seek shelter. 

 The rocks of this part of the coast consist of granite, gneiss, syenite, 

 and porphorio Syenite ; the guano which covers them generally 

 exists in horizontal layers; but sometimes the latter have a strong 

 inclination, aa at Chipana, for instance, where they are nearly 



vertical. The guano deposits are generally covered with an agglo- 

 meration of sand and saline substances, called caliche, which the 



