GAS 



Consequently the speed of move- 

 ment of the molecules of a gas is 

 calculated as the mean or average 

 speed of motion ; the mean speed 

 of hydrogen molecules is 1,859 

 metres,' roughly 2,000 yds., a 

 second, i.e. 25 m. in 22 seconds; 

 the values for nitrogen and oxygen 

 are 492 and 465 respectively. Under 

 similar conditions of temperature 

 and pressure equal volumes of all 

 gases contain an equal number of 

 molecules. The density of a gas is 

 usually related to that of hydrogen ; 

 in such terms the densities are : 

 oxygen, 15*96 ; nitrogen, 14'03 ; 

 coal gas, about 5. In popular 

 usage the term gas implies " coal 

 gas," the nitrous oxide used by 

 the dentist, or " natural gas." See 

 Coal Gas ; Natural Gas ; Lique- 

 faction of Gases ; Chemistry ; 

 Molecule. 



GAS IN MINES. The workings in 

 all classes of mines are liable to 

 contain gas ; but coal mines are 

 peculiarly subject to this con- 

 tingency. The chief gases which 

 occur are sulphuretted hydrogen 

 (HoS), frequently called " stink 

 damp," which doubtless arises 

 from the decomposition of pyrites ; 

 carbon monoxide (CO), " white 

 damp " ; carbon dioxide (CO->) or 

 carbonic acid gas, " choke damp," 

 " black damp," or " after damp " ; 

 and marsh gas (CH 4 ), commonly 

 known as " fire damp." The car- 

 bon monoxide and the carbonic 

 acid gas may be due to natural 

 causes or be simply the residual 

 products of the combustion of 

 explosives used in the mines. Both 

 are injurious to life, the former 

 being a deadly poison. The most 

 important of all these gases, how- 

 ever, is the marsh gas or fire damp, 

 which is the chief agent in the pro- 

 duction of mine explosions. See 

 Mining ; Explosion. 



Gas. Term commonly used 

 collectively to describe the poison- 

 ous and irritating chemicals dis- 

 charged against hostile troops as 

 one phase of modern warfare, 

 irrespective of whether the sub- 

 stances used are actually gases, 

 liquids, or solids. The method was 

 first used in the Great War, con- 

 trary to the provisions of the 

 Hague Convention, the first attack 

 being that made by the Germans 

 at Ypres in April, 1915. 



The first method employed was 

 to discharge clouds of gas against 

 the enemy from cylinders kept in 

 the trenches, but the utility of 

 this method was not only limited 

 by the restricted choice of gases 

 which are suitable, but also by the 

 necessity of only making the attack 

 when weather conditions were 

 favourable. The method has been 

 largely superseded by the use of 



3436 



shell charged with " gas " which is 

 released when the shell explodes. 

 This method was introduced on a 

 large scale by the Germans in the 

 Somme battles of 1916, and shell of 

 this nature became part of the stan- 

 dard equipment of both the artillery 

 and trench mortar batteries. Gas 

 shell permit of a much wider range 

 of chemicals being utilised. 



The chemicals used may be 

 lethal in their effect or incapacitate^ 

 troops either by a lachrymatory 

 effect or by causing violent 

 sneezing, the latter effect also 

 making it impossible for troops to 

 fit or retain their gas masks, when 

 they may be subjected to a bom- 

 bardment with lethal gas. The 

 chief desiderata in gas warfare 

 are : high concentration of the gas 

 in the atmosphere, surprise in 

 tactics, and the use of unexpected 

 chemicals. During the Great War, 

 except in the first unexpected 

 attacks, progress in protective de- 

 vices kept in advance of the gas 

 used, and casualties were not ab- 

 normal. There is no mechanical 

 difficulty in using aeroplane bombs 

 charged with gas, but so far this 

 method has not been employed. 

 See Ammunition ; Chemicaf Shell ; 

 Gas Cloud; Gas Helmet; Gas 

 Poisoning ; Gas Shell ; Lachry- 

 matory Shell ; Mustard Gas ; 

 Sneezing Gas ; Tear Shell. 



Gas-bag. In aeronautics, flex- 

 ible bag made of fabric, and em- 

 ployed to hold the gas in an air- 

 ship. Gas-bag is also slang for 

 the airship itself. See Airship. 



Gas Check. Device to prevent 

 or minimise the escape of pro- 

 pellant gases between the pro- 

 jectile and walls of a gun barrel. 

 Many types of 

 c onstruction 

 were tried to 

 prevent this 

 escape, includ- 

 ing shell with 

 loose bases, the 

 latter being 

 driven forward 

 by the pressure 

 of the propel - 

 lant gases, com- 

 pressing a lead 

 or copper 

 washer against 

 the body of the 

 shell and forc- 

 ing it into the 

 grooves. Lead- 

 coated shell 

 were much used 

 with the early 

 breech- loaders, 

 and another 

 device was a 

 plate 



Gas Check. Sec- 

 tional view of 



check 



cter than the 



GASCOIGNE 



bore, fixed to the base of the shell, 

 this being forced into the shape of 

 a cup and the edges held tightly 

 against the barrel when the piece 

 was fired. Modern gas checks 

 employ a similar principle, but the 

 device is incorporated with the 

 driving band, a lip being formed, 

 under which the powder gases pene- 

 trate, holding the lip firmly against 

 the barrel. See Driving Band; Shell; 

 Windage. 



Gas Cloud. Term employed to 

 define the direct discharge of 

 poison gas in warfare. Chlorine, 

 phosgene, and bromine have been 

 utilised in this way, the gases 

 being compressed into cylinders 

 like those used for oxygen, etc. 



Holes are dug in the front walls 

 of the trenches and the cylinders 

 placed therein, covered with moss 

 soaked in sodium carbonate, and 

 then protected by sandbags. A 

 metal tube is connected to the cylin- 

 der valve and carried over the para- 

 pet. When a gas attack is to be 

 made the valves of all the cylinders 

 on that section of the front are 

 opened, and the gas forms a cloud 

 which will travel down hill or be 

 carried by the wind if the latter is 

 not too strong or gusty. Warning of 

 such attacks is generally given by 

 the noise of the gas escaping from 

 the cylinders, and it is difficult to 

 obtain effective concentration at 

 any distance. Gas clouds were 

 disguised by mixing or alternating 

 them with smoke clouds, but 

 during the later stages of the war 

 were largely superseded by the 

 use of poisons in shell. 



Gascoigne, GEORGE (c. 1525- 

 77). English poet. Born at Car- 

 dington, Bedfordshire, and edu- 

 _ cated at Cam- 

 8 bridge and the 

 Inns of Court, 

 he was M.P. 

 for Bedford, 

 fought in the 

 Low Countries, 

 took part in the 

 famous festival 

 at Kenilworth, 

 and died at 

 Stamford, 

 Oct. 7, 1577. To him is due the 

 first English prose comedy, The 

 Supposes, 1566 (an English adapta- 

 tion of Ariosto's Gli Suppositi), 

 which supplied the underplot of 

 Shakespeare's The Taming of the 

 Shrew. In collaboration with Fran- 

 cis Kinwelmersh he wrote the 

 second English tragedy, Jocasta, 

 1566 (from an Italian version of 

 Euripides' Phoenissae) ; one of the 

 earliest English satires in blank 

 verse, The Steel Glass, 1576 ; the 

 first critical essay on English versi- 

 fication, Certain Notes of Instruc- 

 tion in English Verse, 1575 ; and 



George Gascoigne, 

 English poet 



