FIRE-ARMS 



375 



' Apart from its special interest, as compared with the following experiment, made 

 simultaneously through charcoal, the following points are in themselves remarkable 

 in the results obtained by this filtration through sand: 



' 1st. That the filter continued increasing in efficacy even till the conclusion of the 

 experiment, i.e., for 376 hours, not having lost any of its power when the experiment 

 was terminated. 



' 2nd. That no weighablo quantity of dissolved organic matter was removed by the 

 sand in this experiment ; but it must be remembered that the quantity originally pre- 

 sent was but small. 



' 3rd. Its power of removing soluble salts was considerable ; as a maximum, 21 per 

 cent, of the common salt being separated.' 



On comparing this experiment with the preceding, the following point comes 

 out as showing the difference between the effects of sand and charcoal as filtering media. 



By the charcoal, speaking generally, a considerably larger quantity of the total 

 residue contained in the water was removed than by the sand, their maximum results 

 being respectively as follow : 



FIRE ANNXHIZiATORS. This name is given to a portable machine invented 

 by Mr. Phillips, which is adjusted to produce the immediate production of steam, 

 carbonic acid, and other gases, which could be at once directed on the burning 

 mass. The machine is cylindrical in form, and slightly conical. For use it is charged 

 with the following composition : charcoal 20 parts, nitrate of potash 60 parts, and 

 gypsum 5 parts. These materials are boiled together in water, and afterwards dried 

 in a stove at the temperature of 100. The whole is moulded into the form of a 

 brick, down the axis of which penetrates a hollow cavity for the reception of a bottle, 

 which contains a mixture of chlorate of potash and sugar, surmounted by a globule 

 of sulphuric acid. The charge so prepared is placed in a cylindrical vessel, per- 

 forated in many places, which is itself within another cylindrical vessel, also per- 

 forated for the passage of the gases ; both these are contained in a double cylindrical 

 receiver, the lower part of which contains a quantity of water. The apparatus is 

 closed by two covers, in the outer of which is an opening for the escape of the vapour. 

 In the centre of the cover is placed a spike, for the purpose of breaking the glass 

 bottle deposited in the cavity of the charge. The spike being forced down breaks 

 the bottle, and the sulphuric acid causes the instantaneous combustion of the chlorate 

 of potash and sugar, which fires the charge. The gases now escape through the per- 

 forations, and heating the air in the water-chamber, and causing it to expand, forces 

 the water up a tubular passage into the space between and around the cylindrical 

 vessels placed each within each, and being thus converted into vapour, mixes with the 

 gases, and escapes by the discharge-tube, forming a dense cloud, which rapidly extin- 

 guishes flame. 



Many very successful experiments were made with these fire annihilators, but 

 they have not been much used. There can be no doubt the principle is a correct one. 

 Any arrangement for pouring carbonic acid upon flame would be certain of success, 

 if the cost of production did not stand in the way. A patent was granted in 1873 to 

 Mr. W. B. Dick, of G-lasgow, for improvements in apparatus for extinguishing fires. 

 Carbonic acid gas is generated by the action of sulphuric acid on bicarbonate of soda, 

 and is dissolved in water ; the solution is projected, by the expansive force of the gas, 

 from a strong vessel through a regulator valve and delivery hose. The bottle of acid 

 is held between a fixed bottom-support and a moveable cap, and is broken by striking 

 an external cap. These ' extincteurs ' have been recently supplied to some of the 

 Government offices. 



FIRE-ARMS, MANUFACTURE OF. This article belongs properly to a 

 work on mechanical engineering. It cannot be extended as it should be without 

 encroaching to too great an extent upon the space reserved for the articles which 

 legitimately belong to this Dictionary. It has therefore been allowed to remain as it 

 stood in the last edition : all the main principles connected with the construction of fire- 

 arms being fully described. 



This art is divided into two branches ; that of the metallic, and that of the wooden 



