583 



NATURE 



[December 29, 1921 



time the off-season arrives that infection dies out com- 

 pletely, presumably because the few susceptible rats 

 then surviving are so scattered as to render it diflficult 

 or impossible for infected fleas to perpetuate the 

 epizootic by passing from one rat to another. 



Now the few towns or villages in which plague in- 

 fection is likely to persist through the off-season can 

 be detected with a little practice and with the aid of 

 certain "charts"; and the authors' scheme was to 

 reinforce the natural tendency of plague infection to 

 die out by further reducing the rat population in these 

 centres by poisoning or some other means of destruc- 

 tion. Any future epidemics which might occur 

 within the experimental area would then be entirely 

 dependent on re-importation from without. 



The experiment was carried out in those places, 

 fifty in number, which were considered likely to carry 

 over the infection from one season to the next (of 

 the 407 places excluded as not likely to carry over, 

 only three, in fact, continued to harbour plague 

 throughout the ofl"-season). The agent of destruction 

 was the 'Punjab Rat-exterminator." 



Briefly, the experiment was not a success ; and 

 since there was practically no failure in "spotting 

 the places likely to carry over, since, too, the authors 

 are able to conclude that an epidemic of plague in 

 this area is far more dependent on off-season centres 

 of plague infection within the area than on importa- 

 tion of infection from without, it follows that failure 

 was attributable largely to the inadequacy of the 

 methods of rat-destruction. 



The authors, therefore, determined to concentrate 

 on the improvement of methods of rat-destruction. 

 Traps were found to vary considerably in efficiency, 

 and can be much improved by attention to certain 

 apparently trivial details of construction. Hydro- 

 cyanic acid gas, in general a useful method of de- 

 stroving rats and their fleas, would be of little 

 practical value for the present puqwse unless some 

 method could be devised of rendering Indian houses 

 more airtight while they are being fumigated. 



The most efficient and suitable rat poison, of all 

 those experimented with, was barium carbonate. 

 Three grains is a suitable dose ; this quantity mixed 

 with four times its weight of food material does not 

 diminish the amount of the latter consumed by the 

 rat ; the Punjab rat-exterminator — a phosphorous com- 

 pound — was, howe\er, found to be actively repulsive 

 to the rat. Barium carbonate, again, was found to 

 be twice as poisonous as the Punjab compound, and 

 a lethal dose costs only one-sixtieth as much as one 

 of the latter substance. Arsenious acid would be the 

 most suitable substitute for the barium carbonate if 

 this were not available. Ba]ri flour is the best 

 vehicle. 



The authors' experiments are as yet incomplete, 

 and have, so far, been carried out only in the labora- 

 torv ; thev hope, however, to amplify them and con- 

 firm them under more natural conditions. When, 

 armed with their new knowledge, they return to the 

 practical work of rat destruction, we hope that the 

 problem of plague extermination will be advanced 

 one stage nearer a solution. 



The Carbonisation of Peat in Vertical 

 Gas Retorts. 



THE programme of work undertaken by the Fuel 

 Research Board includes research into the 

 utilisation of machine-won peat, and a report has been 

 issued giving the results of the first series of experi- 

 ments on the carbonisation of peat in vertical gas 



NO. 2722, VOL. 108] 



retorts v^ith steaming. This material was macerated 

 in 1920, spread on the bog at Turraun, air dried and 

 harvested there, and early in 192 1 a hundred ton* 

 were sent to the Fuel Research Station, primarily 

 for experiments upon its use in carbonisation and 

 boiler firing. 



The peat as received at East (jreenwich consisted 

 of hard blocks with a density rather under i, or about 

 twice that of the ordinary hand-cut sods made on the 

 same bog. The water content, about 25 per cent., was 

 reduced on storage under cover to 17 per cent. These 

 peat blocks are reported to have lent themselves ad- 

 mirably, after suitable treatment, to carbonisation in 

 vertical retorts at temperatures between 750° and 

 850° C, and also in steel retorts at 550° and 

 600° C, the resultant charcoal being ideal fuel for 

 suction gas producers. The vertical retort setting for 

 carbonisation was of the Glover-West design, some- 

 what modified, as used in the tests already reported 

 on the steaming process for gas-making from coal. 

 Some difficulties were encountered, mainly of a 

 mechanical order. The peat was not suitable for feed- 

 ing with the ordinary arrangement, and the high 

 percentage of dust which it contained on crushing 

 gave trouble from its being carried forward into the 

 gas main and forming a thick mass with the tar. A 

 through-put of three tons of peat per retort was main- 

 tained. 



After supplying sufficient heat for carbonisation of 

 the peat there were for disposal from each ton of 

 peat 7940 cubic feet of gas of 325 B.Th.U., 12-6 

 gallons of tar, 95^ gallons of liquor of 3-6 oz. strength 

 ])er ton, and 54 cwt. of charcoal. The liquor was 

 weak, and its q.uantity corresponded with some 

 27 lb. of ammonium sulphate per ton. The peat gas, 

 which was very dense, contained 15 to 17 per cent, 

 carbon dioxide, but it burned with a satisfactorv- 

 flame though with only slight luminosity. .\ feature 

 of the gas was the heavy sickly odour which it gave 

 out on combustion. The light spirit amounted to 

 nearlv two gallons per ton of peat. 



The report is supplemented by eight tables in which 

 various thermal and chemical data are collected, in- 

 cluding analyses of the peat and its products, and an 

 examination of the tar oils. J. \\ • C. 



University and Educational Intelligence. 



Aberdeen. — A sjiecial examination for ex-Service 

 students has resulted in the capping of twenty-eight 

 graduates in medicine— M.B. and Ch.B. degrees— of 

 whom four are with distinction. The informal gradua- 

 tion ceremony was conducted on December 24 by the 

 \'ice -Chancellor, Principal the Rev. Sir George Adam 

 Smith. 



Leeds.— The Council of the L'niversity has conferred 

 upon Mr. W. E. H. Berwick the appointment of 

 reader in mathematical analysis. Mr. Berwick has 

 been lecturer in the department of mathematics of the 

 L'niversity since October, 1920. 



The following elections to the scholarships in com- 

 merce have been made by the University of London :— 

 Sir Edward Stern scholarships of 50L a year for two 

 years, W. ^^^ Hewett and K. P. Rush. Sir Ernest 

 "Cassel scholarships of the value of not less than 200L 

 for the studv of commerce in foreign countries, C. E. 

 Benzecrv, W. F. Crick, T. A. Hooker, and F. W 

 Tavlor. 



