550 



NA TURE 



[April 5, 1900 



with or without the use of retarding agents. The powders of 

 this class are ballistite and filite, the former being in sheets, the 

 latter in threads. Originally camphor was introduced, but its 

 use has been abandoned, a small quantity of aniline taking its 

 place. 



Sir Frederick Abel and Prof. Dewar patented in 1889 the use 

 of trinitrocellulose and nitroglycerine, for although, as is well- 

 known, this form of nitrocellulose is not soluble in nitroglycerine, 

 yet by dissolving the bodies in a mutual solvent, perfect incor- 

 poration can be attained. Acetone, is the solvent used in the 

 preparation of " cordite," and for all ammunition except blank 

 charges a certain proportion of vaseline is also added. The 

 combustion of the powder without vaseline gives products so 

 free from solid or liquid substances that excessive friction of the 

 projectile in the gun causes rapid wearing of the rifling, and it is 

 chiefly to overcome this that the vaseline is introduced, for on 

 explosion a thin film of solid matter is deposited in the gun, and 

 acts as a lubricant. 



The proportion of the ingredients are : — 



Nitroglycerine 58 parts. 



Gun-cotton ... ... ... ... ... 37 ,, 



Vaseline ... 5 ,, 



Gun-cotton to be used for cordite is prepared as previously 

 described, but the alkali is omitted, and the mass is not sub- 

 mitted to great pressure, to avoid making it so dense ihat ready 

 absorption of nitroglycerine would not take place. The nitro- 

 glycerine is poured over the dried gun-cotton and first well 

 mixed by hand, afterwards in a kneading machine with the 

 requisite quantity of acetone for 3^ hours. A water jacket is 

 .provided, since on mixing the temperature rises. The vaseline 

 is now added, and the kneading continued for a similar period. 

 The cordite paste is first subjected to a preliminary pressing, 

 and is finally forced through a hole of the proper size in a plate 

 either by hand or by hydraulic pressure. The smaller sizes are 

 wound on drums, whilst the larger cordite is cut off in suitable 

 lengths, the drums and cut material being dried at 100° F., thus 

 driving off the remainder of the acetone. 



. Cordite varies from yellow to dark brown in colour according 

 to its thickness. When ignited it burns with a strong flame, 

 which may be extinguished by a vigorous puff" of air. Macnab 

 and Ristori give the yield of permanent gases from English 

 cordite as 647 c.c, containing a much higher per cent, of carbon 

 monoxide than the gases evolved from the old form of powder. 

 Sir Andrew Noble failed in attempts to detonate the substance, 

 and a rifle bullet fired into the mass only caused it to burn 

 quietly. 



Lyddite is probably the explosive which has received most 

 notice during the past few months. In 1873, Sprengel, in a 

 paper read before the Chemical Society, stated that " picric acid 

 alone contains a sufficient amount of oxygen to render it, with- 

 out the help of foreign oxidisers, a powerful explosive when 

 fired with a detonator. Its explosion is almost unaccompanied 

 by smoke."' 



Picric acid was first prepared by Hausmann in 1878, by treat- 

 ing indigo with nitric acid. It may be made by the direct 

 nitration of phenol (carbolic acid), but a better result is 

 obtained by first dissolving the phenol in sulphuric acid, forming 

 phenol sulphonic acid, which is dissolved in water, and nitrating 

 this compound with nitric acid (i"4). On cooling, the picric 

 acid separates out, and is purified by recrystallisation from hot 

 water, the yellow crystalline product being dried at a temper- 

 ature not exceeding 100° C. 



Picric acid containing as much as 17 per cent, of water can be 

 detonated by a charge of dry picric powder ; a thin layer may 

 also be exploded by a blow between metal surfaces, its sensitive- 

 ness to shock being greatly increased by warming, for at a 

 temperature just below its melting point a pound weight falling 

 from a height of 14 inches will explode it. 



The sensitiveness of picric acid can be reduced by converting 

 the powder into larger masses, this being accomplished either 

 by granulating it with a solution of collodion cotton in ether- 

 alcohol, as in the earlier forms of melinite, or by fusion, which 

 takes place some twenty degrees above the boiling point of 

 water, and casting directly into the shell, as in lyddite and 

 possibly the melinite of the present day. In any condition 

 perfect detonation would yield only colourless gaseous products 

 rich in carbon monoxide, but the bursting of a lyddite shell is 

 frequently accompanied by a yellow smoke, probably formed by 

 undecomposed acid in the form of vapour. The shells appear 



NO. I5«8, VOL. 61] 



to burst in two distinct ways, in one case giving a sharp power- 

 ful explosion with enormous concussion and no yellow smoke, 

 and the other a dull heavy report with the yellow smoke, the 

 two results appearing to be due to perfect decomposition in the 

 first instance, whilst in the second partial decomposition only 

 probably occurs. 



Various mixtures of picric acid or its salts, together with some 

 oxidising agent, have been used from time to time, Abel's 

 powder consisting of ammonium picrate, potassium nitrate, and 

 a small quantity of charcoal. 



It is impossible to deal with the numerous other explosives 

 which are largely in use in such a survey as this, and therefore 

 attention has been confined to those which play the most active 

 part in modern warfare. 



ANTI-PLAGUE INOCULATIONS. 

 'T'HE final proof of Chapter iv. of the Indian Plague Com- 

 mission Report, dealing with Haffkine's anti-plague in- 

 oculations, has already been briefly referred to (p. 422) ; the 

 following are further notes upon its contents : — 



The first paragraphs contain a brief review of the history of 

 preventive inoculation, the Commissioners trace it up to Haff- 

 kine's anti-cholera inoculations, in which a measured quantity 

 of bacteria of known virulence was used. The next practical 

 extension is stated to be the anti-typhoid inoculations introduced 

 by one of the Commissioners (Prof. Wright), in which dead 

 cultures were used ; the first gf these inoculations were done in 

 July and August 1896. Next, they say, come in chronological 

 order the experiments of Versin, Calmette and Borrel, con- 

 jointly in 1895, which showed it was possible to confer a certain 

 amount of immunity against plague by injection of dead cultures 

 of plague bacilli. Mr. Haffkine's anti-plague inoculations, the 

 Commissioners say, represent an extension of this system of 

 preventive inoculation to men. That Mr. Haffkine was not 

 indebted to Versin, Calmette and Borrel, nor to the system of 

 anti-typhoid inoculation, for the suggestion to use dead cultures 

 in his plague prophylactic, is evident from the words used by 

 Mr. Haff'kine in his lecture on "Anti-Cholera Inoculation " re- 

 ported in the British Medical Jonrna/, February 11, 1893: 

 " The microbes introduced under the skin do not propagate, 

 but after a certain time they die and disappear. It is the sub- 

 stances which they contain, and which are set free when they 

 die, that act upon the animal organism and confer immunity 

 upon it. It is found that the same result can be obtained if the 

 microbes be killed before inoculation, and if their dead bodies 

 only be injected." Prof. Wright recognises this, for, in his 

 account of the first anti-typhoid inoculations. Lancet, September 

 19, 1896, he says : " I need hardly point out that these anti- 

 cholera inoculations have served as a pattern for the typhoid 

 vaccinations detailed above." 



Had the Commissioners quoted Mr. Haffkine's experiments 

 with sterilised cultures of cholera bacilli, the anti-typhoid vaccine 

 and the anii-plague prophylactic of Yersin, Calmette and 

 Borrel, would have been shown to be an extension of Haffkine's 

 own anti-cholera vaccine rather than the other way about, as it 

 would appear from the report. 



The report goes on to a very stringent criticism of the method 

 of preparing the prophylactic. A certain proportion of bottles 

 were found to be contaminated. In dealing with large quanti- 

 ties of prophylactic, it is not unlikely that some bottles should 

 become contaminated, possibly by some of the corks not being 

 sterile, as Mr. Haffkine suggests. The fact was not brought 

 before the notice of Mr. Haffkine, but was sprung upon the Com- 

 missioners and mentioned in the daily Press at the time, with the 

 evident intent to detract from the value of the prophylactic. 

 The Commissioners investigated the matter, but found no serious 

 results could be traced to such accidental contaminations. 



The comparative value of the bacterial sediment and of 

 the supernatant fluid is discussed, and, finally, the method of 

 standardisation. 



The process of manufacture is criticised from the point of view 

 of scientific manipulation in a properly equipped laboratory 

 for experiments on a small scale. The Commissioners do not 

 mention the fact that the prophylactic is made on a large scale, 

 as much as 20,000 doses being turned out per day, and this in a 

 laboratory with no proper equipment, and with an insufficient 

 and partially inefficient staff. And now having adversely criti- 

 cised the theory and methods of the General who is conducting 



