DECEMBER. 587 



small bent tube of iron, or of tin, finishing in an 

 iron screw, for screwing to the end of the barre 

 already mentioned. 



If a forge is not at hand, a cast-iron furnace, 

 nine or ten inches diameter, with a circular hole 

 to receive the gun -barrel, and a moveable dome 

 cover to receive the end of a tin pipe, six inches 

 diameter, and 12 feet long, and moveable while up 

 the chimney of the room. The fire to be of char- 

 coal. 



A trough or small tub of water, on legs, adapted 

 in height to the elevation of the gun-barrel when in 

 the furnace, with a perforated shelf in it, on which 

 the jars to stand for receiving the air expelled. 



A correct pair of scales and weights. 



To try whether the gun -barrels or any retorts are 

 really air-tight, an air-pump is very useful, as I have 

 found that blowing in them when under water is 

 not a criterion to be depended on. 



An evaporating saucepan ; that is, a tin sauce- 

 pan with a circular fixed frame of tin, four inches 

 high, to receive a glass jar containing the earth to 

 be dried by the boiling heat of the water, as it is 

 necessary in comparisons, for all specimens to be of 

 the same degree of dryness. 



Pint or quart phials with ground stoppers of sul- 

 phuric acid; muriatic acid; carbonate of potash; 

 solution of potash ; ammonia (caustic) ; muriate of 

 ammonia (the common solution of sal ammoniac). 

 And small phials of the substances mentioned in 

 the Appendix, as tests for the examination of water. 



A few 



