232 VARIETIES OF SHOT-GUNS, ETC. 



five or six times a day, till the colour is dark enough for the 

 fancy. Once or twice a day a scratch-brush is used to re- 

 move the rough oxide and allow the acid to get a deeper 

 bite. When it is considered that enough has been done, boil- 

 ing water is poured over the barrels for several minutes, and 

 while hot, they are rubbed with flannels and finished with a 

 leather and a little beeswax and turpentine. A brighter red 

 colour is produced by the following mixture : 



Take of Tincture of sesquichloride of iron, 1 oz. 

 Spirit of wine, 1 oz. 

 Corrosive sublimate, ^ oz. 

 Nitric acid, ^ oz. 

 Blue vitriol, ^ oz. 

 Water, 2 pints. 



Mix as above, and apply with a piece of flannel twice a day ; 

 scratch it (with a proper scratch brush) clean each time; 

 when dark enough, scratch as clean as possible, and pour 

 boiling water over it. Polish with a fine linen cloth, 

 and, if requisite, a touch of beeswax and turpentine. In- 

 ferior barrels are made to look well to the eye by several 

 tricky methods, chiefly practised at Birmingham, in this 

 country, and at Liege, abroad. Of these the most simple is 

 the use of corrosive sublimate and spirit of wine, which will 

 soon bring out a strong colour if applied in rapidly succeeding 

 layers upon barrels previously prepared with varnish cut 

 away in a pattern, as has been already described at page 216. 

 The smoke stain is the most permanent, but it requires the 

 best metal and a good deal of practice to bring it well out. It 

 is effected by passing the barrels through the flame of a forge 

 at a time when it is of a clear white, without smoke, until the 

 whole is covered with soot ; then remove them to a cool and 

 damp cellar for one or two days, by the end of which time 

 they will have become rusty. Treat them with the scratch- 

 brush as before described, and renew the operation with the 

 flame till the colour is thought to be good. Finish with hot 

 water, as before described. 



Case-hardening is the process adopted for making the parts 

 of the lock, breech, &c., as hard as possible. It is produced 



