February i8, 19 15] 



NATURE 



687 



sory military training are to be looked on with grave 

 suspicion. There is the risk of insidious Prus- 

 sianising. For the undeniable privilege of being part 

 of civilised Europe and for the undeniable distinction 

 of having been willing — on this occasion — to do the 

 right thing at all costs, we shall have to pay a long 

 price, and it is to be feared that part of this price 

 will be the shelving of eugenic endeavours and our 

 connivance thereat. It may be, however, that facts 

 will give the lie to our fears, and that the impoverish- 

 ment of the possible parent-stock of the future will 

 be in some measure counteracted by an enrichment 

 of our social heritage — perhaps even by a nearer 

 approach than we have ever known to positive peace. 



STANDARDISING APPARATUS AND 

 METHODS. 



SE\'ERAL circulars recently received from the 

 Bureau of Standards of the Department of Com- 

 merce, Washington, well illustrate the untiring in- 

 dustry to be found in the American public offices. 

 Circular No. 9 deals with the standardising 

 of glass volumetric apparatus such as flasks, 

 burettes, pipettes, pyknometers, and measuring 

 cylinders. The bureau aims at encouraging excel- 

 lence of quality in such apparatus by co-operating with 

 the makers on one hand, and on the other with the 

 users. To this end the circular describes specifications 

 for the various classes of instruments, and the bureau 

 admits for standardising that apparatus only which 

 conforms to the specifications. It is pointed out in 

 the circular that certain of the demands, such as 

 those regarding the quality of the glass and the 

 process of annealing before calibration, are largely 

 dependent for their fulfilment on the integrity and 

 good faith of the manufacturer. Users can therefore 

 help to secure a high degree of excellence by support- 

 ing conscientious makers and giving consideration in 

 the first place to quality, and only secondly to the 

 matter of cost. The circular supplies information on 

 such points as the best design of apparatus, the 

 material, the methods of marking the graduations, 

 the units of capacity employed, and the limits of error 

 allowable. There are also directions for the mani- 

 pulation of the apparatus during testing ; and for 

 those who wish to calibrate their own burettes and 

 pipettes a brief description of the method to be 

 employed i§ given. 



Circulars Nos. 36, 48, and 222 deal respectively with 

 industrial gas calorimetry, standard methods of gas 

 testing, and flame standards in photometry. These are 

 technical subjects, and it would be impossible in any 

 moderate space to discuss or criticise the very numerous 

 points raised in these circulars. It may suffice to refer 

 to the last-named, and to state that the variation of the 

 light of flame standards of light as determined by 

 atmospheric conditions and as observed by difi'erent 

 observers, or computed by different empirical formulae, 

 are discussed at length, it is often questioned whether 

 the illuminating power of gas, for e.xample, is more 

 fairly determined by comparison with a flame standard 

 which itself is affected by atmospheric conditions 

 (moisture, CO,, pressure"), or whether a standard 

 which is independent of these conditions, such as an 

 electric filament lamp run under strictly defined con- 

 ditions, would not be more correct. As the luminosity 

 of the gas flame itself also is affected by atmospheric 

 conditions, though not identically to the same extent 

 as tlie flame standards of light, the practice in Eng- 

 land is to determine the quality of the gas by refer- 

 ence to a flame standard, and to ignore atmospheric 

 conditions. With an invariable standard of light gas 

 of the same quality would appear to differ more 



NO. 2364, VOL. 94] 



according to the weather conditions than it does with 

 a flame standard, and for this reason if very elaborate 

 corrections are to be avoided the use of the variable 

 standard is considered in this country more appro- 

 priate than that of an invariable standard. 



Three technologic papers issued by the Bureau 

 I are devoted to analytical researches, and deal with 

 the determination of ammonia in illuminating gas, 

 the iodine number of linseed and petroleum oils, and 

 the analysis of printing inks. The first of these, by 

 J. D. Edwards, is of more interest in the United 

 States, where the amount of ammonia in illuminating 

 gas is still subject to control than in the country 

 where no ammonia limits are now in force. It deals 

 with the choice of indicators, effect of carbon dioxide 

 on the titration, errors due to solubility of heads, and 

 to incomplete washing, and the choice of absorption 

 apparatus. Paper No. 37, bv W. H. Smith and J. B. 

 Tuttle, deals with the iodine number of linseed and 

 petroleum oils. The mam point established is that for 

 the iodine solution used (iodine bromide in glacial 

 acetic acid), and probably for other solutions in com- 

 mon use, the conditions of the e.\|>eriment must be 

 more rigorously fixed than is now usual. Thus 

 o-i gram of oil with 25 c.c. of iodine solution gives a 

 lower iodine absorption figure than when the weight 

 of oil and volume of solution are doubled. For 

 mineral oils the absorption increases with excess of 

 iodine, and there is in this case no tendency to reach 

 a constant value. Paper No. 39, on the analysis of 

 printing inks, by the same authors, gives details of 

 the procedure of analysis adopted at the Bureau of 

 Standards for the separation of oil and pigment, the 

 analysis of each separately, and concludes with re- 

 marks on the relation of aniline dyes to paper, and 

 on the accuracv obtainable in the analvsis. 



GASEOUS EXPLOSIONS.^ 



THE investigation of gaseous explosions 

 interest to chemists, physicists, and enginetrs. 

 The chemist studies the laws of combination and 

 dissociation; the physicist deals with modes and rates 

 of inflammation, variation of specific heat, maximum 

 temperatures attained, and laws of radiation and 

 cooling; while the engineer considers both chemical 

 and physical effects as bearing on the practical opera- 

 tion and thermo-dynamics of the internal combustion 

 engine. He also interests himself in the analogous 

 phenomena of inflammable dust explosions as found 

 in coal-mine and flour-mill accidents. The matters 

 of interest are obviously numerous and complicated, 

 and it is accordingly necessan.- to limit their con- 

 sideration to a few points. The points selected will 

 be dealt with as they bear more particularly on the 

 engineering problems of the internal combustion 

 engine. In 1907 the British .\ssociation, at its Lei- 

 cester meeting, appointed a committee of investiga- 

 tion. This committee has been at work ever since, 

 and much light has been thrown by the experiment> 

 of its members upon the facts connected with gaseous 

 explosions as occurring in closed vessels and within 

 engine cylinders having moving pistons. It is now 

 propose to describe some of the work of the com- 

 mittee, dealing first with the phenomena of rising 

 temperature, and secondly with that of cooling after 

 explosion. 



When a mixture of coal gas and air is ignited 

 within a strong closed vessel, it is found that the 

 pressure rises rapidly, attains a maximum, and falls 

 relatively slowly. To this rapid pressure rise is due 

 the term gaseous explosion. Such explosions are 



1 Abstract of dbrr^urse delivered at the Royal Institution on Friday, 

 January 29, by Dr. Dugald Clerk, K.R.S. 



