22 PKESSUKE OF GASES. 



5. The "crusher" employed in the experiments which the 

 author made in common with M. Vieille, will only be described. 

 In this is measured the crushing of a small cylinder of copper 

 placed between a fixed anvil and the head of a piston with a 

 base of known section which receives the action of the gases. 



The eprouvette is of mild steel, 0*022 metres in internal 

 diameter, of a thickness equal to the calibre and of a capacity 

 of 24*3 cms. It is fitted at one end with a plug containing 

 the crushing apparatus which serves for the measurement of 

 the pressures, the other end is closed by a plug carrying the 

 firing arrangement. 



In order to avoid all local action at the contact with the 

 metal, the charge is suspended in the centre of the eprouvette 

 in the form of a cylindrical cartridge, of a shape similar to the 

 interior of the chamber. A fine iron wire capable of being 

 brought to a red heat by electricity traverses the cartridge. 



Fig. 1 shows the drawing of this eprouvette, frequently 

 employed in the investigations of the Commission des matieres 

 explosives. It consists of a cylindrical tube of mild steel, 

 A, strengthened externally, according to Schultz's system, by a 



Fig. 2. End view of the eprouvette. 



steel wire 0'8 mm. in diameter wound on the tube at a tension 

 of 35 kilog. The strengthening covering consists of fifteen coils 

 of wire. 



The cylinder is closed at both ends by the steel plugs BB', 

 the joint between the plugs and the tube being formed by 

 annular copper gas checks, cc'. The plugs are screwed into 

 two discs of wrought iron DD', which latter are held together 

 by six bolts EE' (Fig. 2). 



The ignition of the charge is effected by the incandescence of 

 a metallic wire, stretched between two supports, W ', one of 



