MATCHES FOR ARTILLERY. 37 



ho direct communication with the fire. It should hare a 

 lid fitted to it very closely; and handles to lift it up when 

 necessary. 



Preparation of the Nitrate of Lead. 



To make this salt, nitric acid, or aqua fortis, must be Preparation of 

 7 . trie nitrate of 



saturated with red oxide of lead, or with litharge : but as lead. 



it is necessary that the salt should be neutral, and have no 

 excess either of acid or of base, some precautions in this 

 operation are necessary. If the acid be too much concen- 

 trated, the salt will unite in a mass, crystallize confusedly, 

 and contain a great deal of uncombined oxide. If too 

 little oxide be used, the salt will be acidulous, and soon, 

 destroy the boilers. To obtain i he mean term, 500 parts Proportions of 

 of litharge should be put into a vessel of glass or earthen 

 ware, and on this should be poured 416 parts of nitric 

 acid at 40°, (specific gravity we believe, 1.386) diluted 

 with 128 parts of water ; heat the mixture till the oxide is 

 dissolved, filter, and evaporate to dryness. These pro- 

 portions ought to produce 6 JO parts of nitrate of lead. 



Bath of Nitrate of Lead. 



The nitrate of lead is very soluble in water, and tlie least Liquor for the 



possible quantity of liquid should be employed, that the 



bath, fully loaded, may acquire a temperature far beyond 



that of boiling water, and thus insinuate itself easily into 



the pores of the dilated wood. Accordingly, for every 



pound of nitrate, only a wine quart of water should be 



put into the boiler, or thereabout: but as different kinds 



of wood do not saturate themselves equally with tha salt, 



their proportions must be studied. Experiment has shown, Proportions of 



, ^ . - V ■■. • nitrate to dif- 



that to absorb a pound ot nitrate oi lead, requires near f eren t woods, 



eleven yards of lime >vood, 17| of birch, and near 22 of 



poplar. The lime therefore, when saturated, is the most 



combustible. 



To render the saturation of the wood complete, six Time of boll- 

 hours boiling arc necessary, and hot water must be added, ing ' 

 when the bath sinks so low as to let the salt fall to the 

 bottom. 



Second drying, of the Matches. 



Wlien the matches arc taken cut of the boiler, they must Second drying. 

 2 be 



