PKOGRESS IN EXPLOSIVES GUTTMANN. 295 



Nowadays an explosives factory seems inconceivable without elec- 

 tric light and small motors near buildings or on machines, wdiile even 

 the operation of drying sensitive compositions is performed by elec- 

 tric resistances serving as a perfectly adjustable source of heat. 



Modern explosives have, on the other hand, introduced electrical 

 dangers themselves. In the first lecture the possibility of firing a 

 press charge of black powder by static electricity collecting between 

 ebonite press plates was mentioned. Nitrocellulose is electrified by 

 the current of warm air passing over it when drying, and the neces- 

 sary earthing arrangements were first proposed by Mr. Walter F. 

 Reid, and in many cases especially designed by the author. Mixing 

 machines for blasting gelatine and smokeless powder, especially those 

 provided with reversing gear and belts running in opposite directions, 

 have been known to give long sparks unless properly earthed. Tliis 

 was remedied at Waltham Abbey by saturating the belts with glyc- 

 erin. The powder itself during manipulation Avill generate elec- 

 tricity. Ether vapor given off from smokeless powder and mixed 

 Avith air can be fired with a very small spark, and special care should 

 be taken in preventing its formation. 



The manufacture of high explosives seems a simple operation even 

 to experienced chemists, and the danger attending the process ap- 

 pears to be the only difficulty. As a matter of fact, it bristles with 

 difficulties. A good many have already been mentioned, and a few 

 additional and special points are worthy of note. 



Glycerin is a uniform, easily purified substance, and its nitric ester, 

 nitroglycerin, although sensitive to a blow, especially when frozen, 

 is a chemically stable explosive, tame and harnessed for the service 

 of man. Most nitro compounds of the aromatic series have very great 

 chemical stabilit3^ 



Picric acid is a treacherous substance. It is very powerful, but 

 that is its only recommendation. Those who use it may be asphyxi- 

 ated by the fumes of a prematurely exploding shot; those who are 

 fired at sometimes rejoice when it fails to explode. It requires special 

 mixtures to avoid melting at high temperatures, and it attacks its 

 metal container, forming a dangerous picrate. As an ingredient of 

 other explosives it is useless, since on account of its acid properties it 

 reacts upon the other ingredients. Moreover, it is capable of dis- 

 placing other acids, such as nitric acid in nitrates, a disagreeable 

 property which some patentees have found out to their cost. With 

 Montaigne, " I hope that we shall one day give up its use." 



A more inconvenient material still is nitrocotton. As already 

 stated, cotton is one of the most complex substances known, and for 

 some unexplained reason we have been in the habit of using it after 

 an ill-treatment following upon an undesirable state of cleanliness. 

 At the best, however, we have an almost uncontrollable substance in 

 88292— SM 1908 20 



