280 



SULPHATES OF LIME, BARYTES, AND LEAD. 



Inflammable 



gas. 



Foulness in 

 gun barrels. 



The inflammable gas is produced by the decomposition of 

 the charcoal*; and the ox'gen gas arises from part of the 

 nitre, which is decomposed by the lire. 



After the explosion of gunpowder, we find the inside of 

 the gunbarrel coated with a mixture of alkaline sulphuret 

 and charcoal not decomposed. This alkaline mixture at- 

 tracts the mpisture of the air, and forms a greasy coating 

 tvithm the barrel. If it be loaded in this state, part of the 

 powder adheres to the sides of the barrel ; and on discharg- 

 ing the piece, it catches, and produces what is termed 

 hanging fire. The barrel of a fowling piece therefore should 

 never be used a second day without cleaning, 



Mr. Thomp- 

 son's analysis 

 confirmed by 

 Mr. Berthier 



Component 

 parts of 



gypsum. 



Charcoal of 

 hard woods 

 best. 



XI. 



On the Sulphates of Lime, Bavytcs, and Lead. 



i 



N our last number, p. 174, we gave an analysis of two 

 of these salts by Mr. James Thomson, who was led to the 

 inquiry by the want of agreement between chemists re- 

 specting the proportions of the principles of the sulphate of 

 barytes. A similar reason had led Mr. Berthier, mine en- 

 gineer, to an investigation, which he has inserted in tbe 

 Journal des Mines, for April, 1807, that has but lately 

 reached this country. His analysis corroborates that of Mr. 

 Thomson, after whose paper it would be superfluous to give 

 Mr. Berthier's, I shall therefore simply quote the results 

 he obtained. 



" From the experiments I have above described it fol- 

 lows : 



M 1. That pure common gypsum, in whatever state of 

 mechanical division it may be, contains 21 or 22 per cent of 

 pure water. 



* In France charcoal of alder, poplar, willow, &c. is always used for 

 making gunpowder. The intensity of the fire produced by su h char- 

 coal is iess than of that f.om harder wood. The former, being more 

 porous, would require mare cure in charring than the latter; and they 

 cannot be said to b« in the state of chare aa', unless the, h?v • bee 1 dis- 

 tilled r for when prepared by smothering the fire, there is always a por- 

 tion reduced to the sute of ashes [braise], 



V 2. Tha$ 



