May 12, 192 1] 



NATURE 



ZZ"^ 



tool. It is for this reason, and not because these 

 points are commonly worked on a tortoise core, that 

 1 propose for them the name of "tortoise point." But 

 although the point is triangular in section in typical 

 specimens, it seems that the blow on the convex sur- 

 face of the core was not always successful, and in 

 these cases matters were improved by a good deal of 

 secondary working, so that points like those shown in 

 Fig. I, iii., are not uncommon. Further, although the 

 great majority of tortoise points were worked on tor- 

 toise cores, the "point" was at times produced in- 

 dependently; thus Fig. I, iv., reproduces the front 

 part of a roughly bilobed pebble upon which a par- 

 ticularly good tortoise point has been worked. 



The form of these tortoise points indicates that they 

 were used as a heavy drawing tool, i.e. used with a 

 drawing or dragging motion while the hand exerted 

 considerable pressure. Additional evidence for this 

 view is offered by a certain number of specimens in 

 which the distal portion of the crest, t.e. that nearest 

 the point, shows minute abrasions. The only method 

 of holding the implement allowing this that 1 have 

 been able to discover is to grip the base of the stone 

 between the bent fingers and the ball of the thumb, 

 the convex surface of the tool being towards the palm. 

 The point is then brought in contact with the surface 

 it is desired to cut or grave, the implement being but 

 slightly inclined and drawn steadily away from the 

 body. The suggestion may be made that these tools 

 were used for cutting hides ; such a point would 

 furrow or cut a stiff, sun-dried hide, such as those 

 used by the Veddas, just as it does a piece of stout 

 millboard. 



This form of implement has not, so far as I can 

 discover, been recognised in Europe hitherto ; it is 

 certainly uncommon, for the Abb6 Breuil tells me that 

 he does not know of any example. Its existence is, 

 however, suggested by the reproduction by Commont 

 (■■ Les Hommes Contemporains du Renne dans la 

 Vallee de la Somme," 1914, Fig. 59) of two "instru- 

 ments moust^riens " from the St, Acheul loess, of 

 which one at least seems to represent the "new" 

 implement, C. G. Seligman. 



Toot Baldon, Oxford. 



Molecular Structure and Energy. 



The difficulties with the Lewis-Langmuir theory 

 expressed by Prof. Partington in Nature of April 7 

 have been felt by the writer, and doubtless by others. 

 They may, perhaps, be met in part by the following 

 considerations : — 



(i) In the case of molecules such as carbon dioxide 

 and nitrous oxide the central octet is postulated as 

 tetrahedral, with pairs of electrons at each apex, 

 rather than as cubic. Such an arrangement would 

 diminish rigidity in the axis passing through the three 

 atomic nuclei and permit a measure of rotational 

 energy about this axis. Again, it must be recalled 

 that at higher temperatures the ratio of the specific 

 heats for even diatomic gases falls below 1-4, and 

 that this can well be accounted for by the increasing 

 importance of energy of intramolecular vibration — 

 that is, to-and-fro oscillation of the component 

 atoms. In the case of triatomic gases such as carbon 

 dioxide, the specific heat is much more affected by 

 rise of temperature than in diatomic gases, fre- 

 quencies of vibration in this case corresponding doubt- 

 less to the three well-marked spectral bands of carbon 

 dioxide in the infra-red. For this reason alone the 

 value of 7 for carbon dioxide might well be expected 

 to turn out, even at ordinary temperatures, lower than 

 that anticipated for a gas 'with molecules exhibiting 

 only two degrees of rotational freedom, provided that 



NO. 2689, VOL. 107] 



vibrational energy in this case is not negligible at 

 ordinary temperatures in comparison with translational 

 and rotational energies. The halogen gases consist 

 of pairs of atoms sharing, according to the Lewis- 

 Langmuir theory, only one pair of electrons, which 

 acts as though it were located at a point. It is worth 

 pointing out that this less rigid connection permits the 

 ratio of the specific heats for these gases to fall well 

 below 1-4 even at ordinary temperatures, in consonance 

 with the above suggestion. 



(2) In the case of nitrogen the specific heat data 

 offer no difficulty if, as may be inferred from the 

 models of Langmuir and of Sir J. J. Thomson, the 

 positive nuclei in their ovoid electronic envelope are 

 sufficiently far apart to allow an appreciable moment 

 of inertia in two directions of rotation. 



As the writer has already hinted elsewhere, how- 

 ever, an acetylenic type of union of the two octets 

 concerned may indeed prove more satisfactory in 

 explaining other facts, such as those of molecular 

 dimensions as estimated by Perrin or Rankine or 

 such as will be brought forward in a forthcoming 

 publication from this laboratory by R. N. Pease. 



Alan W. C. Menzies. 



Princeton University, U.S.A., April 19, 



British Laboratory and Scientific Glassware. 



The inclusion of scientific glassware in the pro- 

 posed Key Industries Bill seems to have aroused a 

 sense of apprehension in some quarters, partly on 

 the ground that if Continental products are prohibited 

 users may not be able to procure satisfactory appara- 

 tus, and partly because it is feared that, if given 

 comparative security in the home market, manufac- 

 turers may lose their incentive to improve the quality 

 of their goods and increase prices unduly. 



The lack of confidence in British chemical glass- 

 ware expressed in certain quarters is probably due 

 to unfortunate experience with some of the earliest 

 productions of the industry, when the experience of 

 the blowers was practically negligible and the demand 

 for the goods so urgent that nothing usable was 

 allowed to be sorted out. 



Increased experience, both on the part of the actual 

 glass-blowers in the manipulation of the glass and on 

 that of the technical staffs in the methods of obtain- 

 ing desired results, has achieved great improvement in 

 the quality of the products, and the better classes of 

 British laboratory glassware compare favourably with' 

 any other. 



As regards the quality of the glass itself, very 

 thorough tests have been made by a trustworthy and 

 impartial authority (see Journal of the Society of 

 Glass Technology, 1917, vol. i., p. 153), and in the 

 conclusions arrived at appears the statement : "Taking 

 all the tests into consideration, the six best glasses 

 are B, C, D, E, F, and G, and this list includes all 

 the British glasses in the market. . . . ]ena glass, A, 

 comes seventh on the list." Samples of post-war Jena 

 laboratory ware with the well-known " Schott " stamp 

 are inferior in all but appearance to the pre-war goods. 



Further scientific investigation into the problem of 

 annealing laboratory glassware and the adaptation by 

 manufacturers of the inforihation so obtained have 

 led to great improvement in the direction of reduced 

 liability to cracking in use due to temperature diflfer- 

 ences. This was formerly a frequent cause of com- 

 plaint, but methods of annealing now in use are so 

 efficient that British laboratory glassware will fulfil 

 anv reasonable requirements. 



The average standard of British graduated af>- 

 paratus is distinctly higher as regards accuracy of - 



