344 



NATURE 



[November io, 1921 



Liquid Air Explosives. 



A N Order in Council (192 1, No. 1194) has been 

 **■ issued exempting^ explosives made by im- 

 pregnating absorbent carbonaceous material with 

 liquid air or oxygen from that provision of the 

 Explosives Act which requires the manufacture 

 of explosives to be carried out in licensed pre- 

 mises. This Order will, therefore, enable free 

 competition between explosives of the usual type 

 and mixtures of liquid oxygen with a fuel that 

 can be made on the spot shortly before firing. 



Liquid oxygen explosives originated in Ger- 

 many, but before the war had no great vogue. 

 During the war they were used on a fairly large 

 scale by the Germans in non-gaseous coal mines, 

 in iron mines, and for the destruction of machinery 

 in French steel plants. This development was 

 occasioned by the need for. conserving Germany's 

 supply of nitrates for the manufacture of military 

 explosives. 



The increasing cost of explosives and the im- 

 proved methods of obtaining liquid oxygen make 

 the problem of producing explosives by the simple 

 method of saturating materials like wood-meal 

 with liquid oxygen an attractive one. The ex- 

 plosives so produced also present certain advan- 

 tages, especially as regards freedom from danger 

 in transport, storage, and handling, but they have 

 certain inherent disadvantages : thus, the rapid 

 evafX)ration of the liquid oxygen necessitates 

 rapid firing and so limits the number of shots 

 that can be fired in one blast; it is necessary to 

 have a liquefying jilant cloSe at hand; and the 

 explosive cannot be used in fiery mines. 



The plant required for liquefaction must be 

 capable of turning out a product containing at 

 least 85 per cent, of liquid oxygen. This is con- 

 veyed in Dewar vessels to the proximity of the 

 rock face, where it is poured over a paper cart- 

 ridge containing carbonaceous matter of different 

 kinds, such as carbonised cork, or wood-meal, 

 with or without the aiddition of petroleum. The 

 impregnation of this cartridge with the liquid 

 oxygen is carried out in a cylindrical vacuum- 

 jacketed vessel, care being taken that the im- 

 pregnated cartridge contains sufficient oxygen to 

 ensure the total combustion of the carbonaceous 

 filling and of its paper envelope. The impreg- 

 nated cartridges are then pushed into the bore 

 hole, where they are detonated by means of the 

 usual detonator, or in some cases simply by a 

 gunpowder fuze. According to another method 

 the cartridges are impregnated in the bore-hole 

 itself. The violence of this explosive is compar- 

 able with that of the more intense blasting agents, 

 but much depends upon the manipulative skill of 

 the workers. 



For industrial purposes, since the war, there 

 has been a general reversion to explosives based 

 on nitrates, but it is understood that liquid air 

 explosives are still used in Germany to a limited 

 extent, and that experiments are being made 

 with them in certain French Departments. 

 Their investigation is also being carried 

 on by the United States Bureau of Mines, 

 which has issued a preliminary bulletin on 

 the subject. 



Obituary. 



Prof. F. A. Bainbridge, F.R.S. 



PROF. FRANCIS ARTHUR BAINBRIDGE 

 passed away on October 27. His friends 

 knew he was not well enough to carry on his usual 

 busy life of teaching and research, but none fore- 

 saw that his life would be suddenly cut short by 

 heart failure. He was only forty-seven years old 

 and in the prime of his career. Our deep sym- 

 pathy goes out to his widow and little daughter. 



Prof. Bainbridge had for years been a man of 

 poor physique, and it was a wonder to his friends 

 how, in spite of frequent attacks of illness, he 

 contrived to do so much useful work. He was 

 modest and retiring, but his catholic interest in 

 scientific work and in things in general made 

 him a delightful and lovable companion. He was 

 a skilful experimenter, a clear writer, and an 

 excellent teacher. Such men we can ill spare. 

 The book (" Essentials of Physiology ") he wrote 

 with the late Prof. Menzies is highly esteemed, 

 and illustrates to the full the power he had of 

 interesting his readers and of making crooked 

 paths straight. 



Prof. Bainbridge was born atStdckton-om-Tees, 



NO. 2715, VOL. 108] 



educated at the Leys School, and then at Trinity 

 College, Cambridge. His medical studies were 

 carried out at St. Bartholomew's, and after a 

 brilliant academic career he filled several minor 

 posts in that hospital. His earlv researches were 

 carried out at University College. Among the 

 positions he held were British Medical Research 

 Scholar, demonstrator in pharmacology at St. 

 Bartholomew's, Gordon lecturer on pathology at 

 Guy's, Jenner Memorial student and assistant 

 bacteriologist at the Lister Institute, later the 

 professorship of physiology at Newcastle (191 1), 

 and finally, 1915, he returned to his old school, 

 St. Bartholomew's, as university professor of 

 physiology. At the outbreak of war he at 

 once offered his services, received a temporary 

 commission in the R.A.M.C., and had charge of 

 a military hospital at Newcastle ; he worked also 

 on the action of poison gases at Millbank, and 

 gave lectures on that subject in cadet training 

 schools throughout the country ; but the stress of 

 work was too great, and his health broke down, 

 so that he had to resign his commission. His 

 devotion to duty of all kinds made him an 



